The CHIMERE chemistry-transport model v2023r1 Menut, Laurent; Cholakian, Arineh; Pennel, Romain ...
Geoscientific Model Development,
07/2024, Letnik:
17, Številka:
14
Journal Article
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A new version of the CHIMERE model is presented. This version contains both computational and physico-chemical changes. The computational changes make it easy to choose the variables to be extracted ...as a result, including values of maximum sub-hourly concentrations. Performance tests show that the model is 1.5 to 2 times faster than the previous version for the same setup. Processes such as turbulence, transport schemes and dry deposition have been modified and updated. Optimization was also performed for the management of emissions such as anthropogenic and mineral dust. The impact of fires on wind speed, soil properties and leaf area index (LAI) was added. Pollen emissions, transport and deposition were added for birch, ragweed, olive and grass. The model is validated with a simulation covering Europe with a 60 km × 60 km resolution and the entire year of 2019. Results are compared to various measurements, and statistical scores show that the model provides better results than the previous versions.
We present a comprehensive study integrating satellite observations of ozone pollution, in situ measurements, and chemistry-transport model simulations for quantifying the role of anthropogenic ...emission reductions during the COVID-19 lockdown in spring 2020 over Europe. Satellite observations are derived from the IASI+GOME2 (Infrared Atmospheric Sounding Interferometer + Global Ozone Monitoring Experiment 2) multispectral synergism, which provides better sensitivity to near-surface ozone pollution. These observations are mainly analysed in terms of differences between the average on 1-15 April 2020, when the strictest lockdown restrictions took place, and the same period in 2019. They show clear enhancements of near-surface ozone in central Europe and northern Italy, as well as some other hotspots, which are typically characterized by volatile organic compound (VOC)-limited chemical regimes. An overall reduction of ozone is observed elsewhere, where ozone chemistry is limited by the abundance of NO.sub.x . The spatial distribution of positive and negative ozone concentration anomalies observed from space is in relatively good quantitative agreement with surface in situ measurements over the continent (a correlation coefficient of 0.55, a root-mean-squared difference of 11 ppb, and the same standard deviation and range of variability). An average difference of â¼ 8 ppb between the two observational datasets is observed, which can partly be explained by the fact the satellite approach retrieves partial columns of ozone with a peak sensitivity above the surface (near 2 km of altitude over land and averaging kernels reaching the middle troposphere over ocean).
During the West African summer monsoon, pollutants emitted in urbanized coastal areas modify cloud cover and precipitation patterns. The Dynamics-Aerosol-Chemistry-Cloud Interactions in West Africa ...(DACCIWA) field campaign provided numerous aircraft-based and ground-based observations, which are used here to evaluate two experiments made with the coupled WRF–CHIMERE model, integrating both the direct and indirect aerosol effect on meteorology. During one well-documented week (1–7 July 2016), the impacts of anthropogenic aerosols on the diurnal cycle of low-level clouds and precipitation are analyzed in detail using high and moderate intensity of anthropogenic emissions in the experiments. Over the continent and close to major anthropogenic emission sources, the breakup time of low-level clouds is delayed by 1 hour, and the daily precipitation rate decreased by 7.5 % with the enhanced anthropogenic emission experiment (with high aerosol load). Despite the small modifications on daily average of low-level cloud cover (+2.6 %) with high aerosol load compared to moderate, there is an increase by more than 20 % from 14:00 to 22:00 UTC on hourly average. Moreover, modifications of the modeled low-level cloud and precipitation rate occur far from the major anthropogenic emission sources, to the south over the ocean and to the north up to 11∘ N. The present study adds evidence to recent findings that enhanced pollution levels in West Africa may reduce precipitation.
Despite the international agreement to reduce global warming to below 2 degrees C, the Intended Nationally Determined Contributions submitted for the COP21 would lead to a global temperature rise of ...about 3 degrees C. The relative consequences of such a one-degree additional warming have not yet been investigated for regional air quality. Here we found that a + 3 degrees C global pollutant emission trajectory with respect to pre-industrial climate (reached along the 2040-2069 period under a RCP8.5 scenario) would significantly increase European ozone levels relative to a 2 degrees C one (reached along the 2028-2057 period under a RCP4.5 scenario). This increase is particularly high over industrial regions, large urban areas, and over Southern Europe and would annihilate the benefits of emission reduction policies. The regional ozone increase mainly stems from the advection of ozone at Europe's boundaries, themselves due to high global methane concentrations associated with the RCP8.5 emission scenario. These results make regional emission regulation, combined with emissions-reduction policies for global methane, of crucial importance.
Agriculture is the main source of ammonia (NH3) in France, an important gaseous precursor of atmospheric particulate matter (PM). National
and global emission inventories are known to have difficulty ...representing the large spatial and temporal variability inherent to
atmospheric NH3. In this study, we compare NH3 emissions in France during spring 2011 from one reference inventory, the TNO
inventory, and two alternative inventories that account in different manners for both the spatial and temporal variabilities of the emissions:
(i) the NH3SAT satellite-derived inventory based on IASI NH3 columns and (ii) the CADASTRE-CIT inventory that combines
NH3 emissions due to nitrogen fertilization calculated with the mechanistic model VOLT'AIR on the database of the CADASTRE_NH3
framework and other source emissions from the CITEPA. The total spring budgets, from March to May 2011, at the national level are higher when
calculated with both alternative inventories than with the reference, the difference being more marked with CADASTRE-CIT. NH3SAT and
CADASTRE-CIT inventories both yield to large NH3 spring emissions due to fertilization on soils with high pH in the northeastern part of
France (65 and 135 kt NH3, respectively, vs. 48 kt NH3 for TNO-GEN), while soil properties are not accounted for by the
TNO-GEN methodology. For the other parts of France, the differences are smaller. The timing of fertilization and associated ammonia emissions is
closely related to the nitrogen requirements and hence the phenological stage of the crops, and therefore to the crop year's specific weather
conditions. Maximum emissions are observed in March for 2011 for some regions for both alternative inventories, while April is the period with
maximum emissions for the reference inventory regardless of the region or the year. Comparing the inventories at finer temporal resolutions, typically at
daily scale, large differences are found. The convergence of alternative, independent and complementary methods on the spatiotemporal representation
of the spring NH3 emissions, particularly over areas where the contribution of mineral fertilizer spreading to the spring budget is strong,
encourages further developments in both prospective complementary directions, as this will help improve national NH3 emission inventories.
We use the OMI‐QA4ECV‐v1.1 NO2 tropospheric columns over the 10‐year 2008–2017 period to confront satellite‐based trends in NO2 concentrations to those from the state‐of‐the‐art regional ...chemistry‐transport model CHIMERE and to evaluate the bottom‐up anthropogenic and biogenic NOx emissions in Europe. A focus is made for the 30 most populated urban areas in Europe. Over urban areas in Western Europe, except for coastal cities, OMI confirms the drop in the simulated CHIMERE NO2 tropospheric columns based on the latest country emission official reporting. OMI hardly shows significant negative trends over Central and Eastern Europe urban areas. Increasing biogenic emissions helps reconciling CHIMERE and OMI trends over urban areas in Central Europe and over rural areas, confirming the importance of accounting for non‐anthropogenic emissions to assess long‐term trends. Over Eastern Europe, our results question emission reductions estimated for particular sectors and in particular the road transport, public power, and industrial emissions.
Plain Language Summary
We evaluate anthropogenic and biogenic nitrogen oxides (NOx) emissions in Europe by analyzing nitrogen dioxide (NO2) 10‐yr trends both from satellite observations and from simulations. A focus is made for the 30 most populated urban areas in Europe, particularly exposed to air pollution. The similarities and discrepancies between simulations and satellite observations indeed must be investigated. It is important particularly for policy implications as anthropogenic emissions are based on the official reported emissions form the basis for negotiation on emission reductions in the EU and are used to assess if countries meet their agreed emission ceilings.
Key Points
Over urban areas in Western Europe, OMI confirms the drop of the simulated CHIMERE NO2 tropospheric vertical column density columns, based on the latest country emission reporting
Increasing biogenic emissions reconciles CHIMERE and OMI over urban areas in Central Europe and over rural areas, confirming their importance to assess long‐term trends
Over Eastern Europe, our results question emission reductions estimated for particular sectors such as road transport, public power and industrial emissions
During the monsoon season, pollutants emitted by large coastal cities and
biomass burning plumes originating from central Africa have complex transport
pathways over southern West Africa (SWA). The
...Dynamics–Aerosol–Chemistry–Cloud Interactions in West Africa (DACCIWA) field
campaign has provided numerous dynamical and chemical measurements in and
around the super-site of Savè in Benin (≈185 km away from the
coast), which allows quantification of the relative contribution of advected
pollutants. Through the combination of in situ ground measurements with
aircraft, radio-sounding, satellite, and high-resolution chemistry-transport
modeling with the CHIMERE model, the source attribution and transport
pathways of pollutants inland (here, NOx and CO) are
carefully analyzed for the 1–7 July 2016 period. The relative contributions
of different sources (i.e., emissions from several large coastal cities) to
the air quality in Savè are characterized. It is shown that a systematic
diurnal cycle exists with high surface concentrations of pollutants from
18:00 to 22:00 UTC. This evening peak is attributed to pollution transport
from the coastal city of Cotonou (Benin). Numerical model experiments
indicate that the anthropogenic pollutants are accumulated during the day
close to the coast and transported northward as soon as the daytime
convection in the atmospheric boundary layer ceases after 16:00 UTC,
reaching 8∘ N at 21:00 UTC. When significant biomass burning
pollutants are transported into continental SWA, they are mixed with
anthropogenic pollutants along the coast during the day, and this mixture is
then transported northward. At night, most of the coastal anthropogenic
plumes are transported within the planetary boundary layer (below about
500 m above ground level), whereas the biomass burning pollutants are mostly
transported above it, thus generally not impacting ground level air quality.
Modelling of mineral dust is often done using one single mean species. But for biogeochemical studies, it could be useful to access to a more
detailed information on differentiated mineral species ...and the associated chemical composition. Differentiating between mineral species would also
induce different optical properties and densities and then different radiative impact, transport and deposition. In this study, the mineralogical
differentiation is implemented in the CHIMERE regional chemistry-transport model, by using global databases. The results show that this
implementation does not change the results much in terms of aerosol optical depth, surface concentrations and deposition fluxes. But the information
on mineralogy, with a high spatial (a few kilometres) and temporal (1 h) resolution, is now available and is ready to be used for future
biogeochemical studies.
Carbon monoxide, CO, and fine atmospheric particulate matter,
PM2.5, are analyzed over the Guinean Gulf coastal region using the
WRF-CHIMERE modeling system and observations during the beginning of ...the
monsoon 2006 (from May to July), corresponding to the Africa
Multidisciplinary Monsoon Analysis (AMMA) campaign period. Along the Guinean Gulf coast, the contribution of long-range pollution
transport to CO or PM2.5 concentrations is important. The contribution
of desert dust PM2.5 concentration decreases from ∼ 38 % in
May to ∼ 5 % in July. The contribution of biomass burning
PM2.5 concentration from Central Africa increases from
∼ 10 % in May to ∼ 52 % in July. The anthropogenic
contribution is ∼ 30 % for CO and ∼ 10 % for
PM2.5 during the whole period. When focusing only on anthropogenic pollution, frequent northward transport
events from the coast to the Sahel are associated with periods of low wind
and no precipitation. In June, anthropogenic PM2.5 and CO concentrations
are higher than in May or July over the Guinean coastal region. Air mass
dynamics concentrate pollutants emitted in the Sahel due to a meridional
atmospheric cell. Moreover, a part of the pollution emitted remotely at the
coast is transported and accumulated over the Sahel. Focusing the analysis on the period 8–15 June, anthropogenic pollutants
emitted along the coastline are exported toward the north especially at the
beginning of the night (18:00 to 00:00 UTC) with the establishment of the
nocturnal low level jet. Plumes originating from different cities are mixed
for some hours at the coast, leading to high pollution concentration, because
of specific disturbed meteorological conditions.
Up-to-date and accurate emission inventories for air pollutants are
essential for understanding their role in the formation of tropospheric
ozone and particulate matter at various temporal scales, ...for anticipating
pollution peaks and for identifying the key drivers that could help mitigate
their concentrations. This paper describes the Bayesian variational inverse
system PYVAR-CHIMERE, which is now adapted to the inversion of reactive
species. Complementarily with bottom-up inventories, this system aims at
updating and improving the knowledge on the high spatiotemporal variability
of emissions of air pollutants and their precursors. The system is designed
to use any type of observations, such as satellite observations or surface
station measurements. The potential of PYVAR-CHIMERE is illustrated with
inversions of both carbon monoxide (CO) and nitrogen oxides (NOx) emissions in Europe, using the MOPITT and
OMI satellite observations, respectively. In these cases, local increments
on CO emissions can reach more than +50 %, with increases located mainly
over central and eastern Europe, except in the south of Poland, and
decreases located over Spain and Portugal. The illustrative cases for
NOx emissions also lead to large local increments (> 50 %), for example over industrial areas (e.g., over the Po Valley) and
over the Netherlands. The good behavior of the inversion is shown through
statistics on the concentrations: the mean bias, RMSE, standard deviation,
and correlation between the simulated and observed concentrations. For CO,
the mean bias is reduced by about 27 % when using the posterior emissions,
the RMSE and the standard deviation are reduced by about 50 %, and the
correlation is strongly improved (0.74 when using the posterior emissions
against 0.02); for NOx, the mean bias is reduced by about 24 % and the
RMSE and the standard deviation are reduced by about 7 %, but the
correlation is not improved. We reported strong non-linear relationships
between NOx emissions and satellite NO2 columns, now requiring a
fully comprehensive scientific study.
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