Impact of Coronavirus Outbreak on NO2 Pollution:
Assessed Using TROPOMI and OMI Observations

Spaceborne NO2 column observations from two high‐resolution instruments, Tropospheric Monitoring Instrument (TROPOMI) on board Sentinel‐5 Precursor and Ozone Monitoring Instrument (OMI) on Aura, reveal unprecedented NO2 decreases over China, South Korea, western Europe, and the United States as a result of public health measures enforced to contain the coronavirus disease outbreak (Covid‐19) in January–April 2020. The average NO2 column drop over all Chinese cities amounts to −40% relative to the same period in 2019 and reaches up to a factor of ~2 at heavily hit cities, for example, Wuhan, Jinan, while the decreases in western Europe and the United States are also significant (−20% to −38%). In contrast with this, although Iran is also strongly affected by the disease, the observations do not show evidence of lower emissions, reflecting more limited health measures.

 

Fig1 China

 

Figure 1: TROPOMI NO2 columns over China (a) before and (b–e) after the lockdowns (shown by padlocks) due to Covid‐19. For comparison, columns over the same time periods are shown for 2019. The week of Chinese new year holiday is indicated by the red lantern shown inset panels (b) and (h). The New Year holiday covers 4–10 February in 2019 and 24–30 January in 2020 (exceptionally extended to 2 February because of Covid‐19). Partial loosening of the restrictions is suggested by the smaller padlock in panel (e). Gray areas indicate no valid data.

 

Reference:

  • Bauwens, M., S. Compernolle, T. Stavrakou, J.-F. Müller, J. van Gent, H. Eskes, P. F. Levelt, R. van der A, J. P. Veefkind, J. Vlietinck, H. Yu, and C. Zehner: Impact of coronavirus outbreak on NO2 pollution assessed using TROPOMI and OMI observations, Geophys. Res. Lett., 47, e2020GL087978, https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020GL087978, 2020.

 

Press releases:

 

 

 

 

Drastic increase of isoprene fluxes in the future climate

Isoprene is the dominant biogenic hydrocarbon emitted into the atmosphere. It plays a key role in the atmospheric composition because of its influence on tropospheric ozone and its contribution to fine particle formation. Isoprene emissions respond strongly to changes in temperature and solar radiation, and are therefore strongly dependent on the warming climate. Here we use  the MEGAN-MOHYCAN biogenic emission model to estimate high-resolution isoprene fluxes over Europe in the past 35 years and in different projection scenarios for the end-of-the-century climate.

In this study we used the MEGAN (Model of Emissions of Gases and Aerosols from Nature) emission model coupled with the MOHYCAN (Model of HYdrocarbon emissions by the CANopy) canopy model to calculate the isoprene fluxes emitted by vegetation in the recent past (1979–2014), and in the future (2070–2099) over Europe. As a result of the changing climate, modeled isoprene fluxes increased by 1.1% per year on average in Europe over 1979–2014, with the strongest trends found over eastern Europe and European Russia. For the 1979–2014 period the model used ECMWF meteorology, whereas for the comparison of current with projected emissions, the meteorology was simulated by the ALARO climate model. Depending on the climate scenario, isoprene fluxes were found to increase between 7% and 83% compared to the control run, and even stronger increases were found when considering the potential impact of CO2 fertilization. However, the inhibitory CO2 effect goes a long way towards canceling these increases.

Cordex

Fig. 1. Relative differences in isoprene emissions between the control (CTRL) run and three climate scenarios considering the effect of (A) climate, (B) climate and fertilization, (C, D) climate and moderate or strong inhibition, (E) climate, fertilization, and strong inhibition, from Bauwens et al. Recent past (1979–2014) and future (2070–2099) isoprene fluxes over Europe simulated with the MEGAN–MOHYCAN model. Biogeosciences, 15, 3673-3690, 2018.

 

 

 

 

New assessment of the global carbon monoxide source

The hydroxyl radical (OH) is the main detergent in the atmosphere and its abundance controls the concentrations of carbon monoxide (CO), a primary pollutant gas. As a result, the carbon monoxide emissions determined through inverse modeling constrained by satellite data depend crucially upon the OH levels simulated with models. Here we have combined observation-based constraints on OH levels, satellite CO data from the IASI sensor, and the IMAGES atmospheric model to provide improved global estimates of CO emissions.
The sources of CO include direct emissions and photochemical production due to the oxidation of hydrocarbons. The dominant CO sink is its reaction with OH, CO has therefore a strong influence on the oxidative capacity of the atmosphere and on the removal of air pollutants. However, most chemistry transport models fall short of reproducing constraints on OH levels derived from methyl chloroform (MCF) observations. In this study, we prescribe different OH fields compatible with MCF data in the IMAGES global model to infer CO fluxes constrained by IASI CO data. Each OH field leads to a different set of optimized emissions. Differences of 40% in the top‐down global anthropogenic CO emissions are found when varying the OH levels, and even larger differences are found regionally, e.g. in China and the United States. Comparisons with independent surface and aircraft observations indicate that the inversion adopting the lowest average OH level in the Northern Hemisphere (18% lower than the best estimate based on MCF measurements) provides the best overall agreement with all tested observation datasets. 

CO 

Fig.1. Mean annual updates (optimized/prior) of anthropogenic, biomass burning, and biogenic emissions in the optimization HN and LN, assuming either very high and very low OH in the Northern Hemisphere, from Müller et al. Top‐Down CO Emissions Based On IASI Observations and Hemispheric Constraints on OH Levels. Geophys. Res. Lett., https://doi.org/10.1002/2017GL076697, 2018.

Impact of Coronavirus Outbreak on NO2 Pollution:
Assessed Using TROPOMI and OMI Observations

Spaceborne NO2 column observations from two high‐resolution instruments, Tropospheric Monitoring Instrument (TROPOMI) on board Sentinel‐5 Precursor and Ozone Monitoring Instrument (OMI) on Aura, reveal unprecedented NO2 decreases over China, South Korea, western Europe, and the United States as a result of public health measures enforced to contain the coronavirus disease outbreak (Covid‐19) in January–April 2020. The average NO2 column drop over all Chinese cities amounts to −40% relative to the same period in 2019 and reaches up to a factor of ~2 at heavily hit cities, for example, Wuhan, Jinan, while the decreases in western Europe and the United States are also significant (−20% to −38%). In contrast with this, although Iran is also strongly affected by the disease, the observations do not show evidence of lower emissions, reflecting more limited health measures.

 

Fig1 China

Fig. 1. TROPOMI NO2 columns over China (a) before and (b–e) after the lockdowns (shown by padlocks) due to Covid‐19. For comparison, columns over the same time periods are shown for 2019. The week of Chinese new year holiday is indicated by the red lantern shown inset panels (b) and (h). The New Year holiday covers 4–10 February in 2019 and 24–30 January in 2020 (exceptionally extended to 2 February because of Covid‐19). Partial loosening of the restrictions is suggested by the smaller padlock in panel (e). Gray areas indicate no valid data.

 

Reference:

  • Bauwens, M., S. Compernolle, T. Stavrakou, J.-F. Müller, J. van Gent, H. Eskes, P. F. Levelt, R. van der A, J. P. Veefkind, J. Vlietinck, H. Yu, and C. Zehner: Impact of coronavirus outbreak on NO2 pollution assessed using TROPOMI and OMI observations, Geophys. Res. Lett., 47, e2020GL087978,  https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020GL087978, 2020.

Press releases:

MAGRITTE : Model of Atmospheric Composition at Global and Regional scales using Inversion Techniques for Trace Gas Emissions

 

  • Chemical mechanism

The chemical mechanism is described in Müller, J.-F. et al.: Chemistry and deposition in the Model of Atmospheric composition at Global and Regional scales using Inversion Techniques for Trace Gas Emissions (MAGRITTE v1.0). Part A: Chemical mechanism, Geosci. Model Dev., 12, 2307-2356, https://doi.org/10.5194/gmd-2018-316, 2019.

Download the mecanism in KPP format

MAGRITTEv1.1.eqn

MAGRITTEv1.1.spc

Rates_for_MAGRITTEv1.1.f

Last modified : 14 June 2019

Absorption cross sections used in MAGRITTEv1.1 (hydroperoxycarbonyls, nitroxycarbonyls, keto-enols)

MAGRITTEv1.1_cross_sections.tar

 

  • Dry deposition velocity calculation

The dry deposition velocities are calculated as described in

Müller, J.-F. et al.: Chemistry and deposition in the Model of Atmospheric composition at Global and Regional scales using Inversion Techniques for Trace Gas Emissions (MAGRITTE v1.0). Part B: Dry deposition, Geosci. Model Dev. Discuss., https://doi.org/10.5194/gmd-2018-317, in review, 2018.

The code is divided in two parts :

1) The package

MOHYCAN_code.tar.gz

Last modified : 20/12/2018

 includes Fortran code and input files for calculation of stomatal resistances for H2O.

2) The package

Deposition_model_code.tar.gz

Last modified : 20/12/2018

includes Fortran code and input files for the general calculation of dry deposition velocities.

Readme_deposition

Last modified : 20/12/2018

 Resolution is 0.5x0.5 degree. The user should provide meteorological fields. Typical values of those variables are assumed in the code.

 

  • Dry deposition velocity measurements

The dry deposition velocity measurements used in Müller et al. (GMDD) can be found below.

Dry Deposition Observations

Last modified : 20/12/2018

 

References

  • Müller, J.-F., T. Stavrakou, J. Peeters: Chemistry and deposition in the Model of Atmospheric composition at Global and Regional scales using Inversion Techniques for Trace Gas Emissions (MAGRITTE v1.0). Part A: Chemical mechanism, Geosci. Model Dev. Dissuss., https://doi.org/10.5194/gmd-2018-316, in review, 2018.
  • Müller, J.-F., T. Stavrakou, Maite Bauwens, S. Compernolle, J. Peeters: Chemistry and deposition in the Model of Atmospheric composition at Global and Regional scales using Inversion Techniques for Trace Gas Emissions (MAGRITTE v1.0). Part B: Dry deposition, Geosci. Model Dev. Dissuss., https://doi.org/10.5194/gmd-2018-317, in review, 2018.