DS0104 - Innovations scientifiques et technologiques pour anticiper ou remédier les risques environnementaux

Pollution in Eastern Asia: towards better air quality prevision and impacts’ evaluation – PolEASIA

PolEASIA: Pollution in Eastern ASIA: towards better air quality prevision and impacts’ evaluation

China's rapid economic development and urbanization in recent decades have led to a sharp increase in pollutant emissions and concentrations of pollutants exceeding the pollution thresholds recommended by the World Health Organization. Better knowledge, understanding and monitoring pollution in China are essential to assess the impacts of this pollution, improve forecasting capabilities and refine emission control strategies.

towards better air quality prevision and impacts’ evaluation of Chinese pollution

Based on an ambitious approach combining observations and modeling capable of linking local and global scales, the PolEASIA project aims to better quantify the distribution of pollutants (ozone and aerosols), their sources, their variability and their recent and future evolution. A particular attention is paid to the natural and anthropogenic part of Asian pollution. Advances in the understanding of Asian pollution will support an assessment of the impact of Chinese pollution in terms of (i) the export of pollutants and their impact on regional and global chemical composition; (Ii) the additional radiative forcing induced by the emitted and produced short-lived climate forcers (ozone and aerosol); (Iii) health by quantifying the long-term consequences of pollution on health. These advances, notably in terms of modeling and numerical methods, will also allow the development of an operational air quality forecasting system that is well assessed and marketable, thus ensuring a high visibility of French technology and a better export capacity of these products. Impact modules will be added to this system to provide user-friendly applications to provide comprehensive indices for health and visibility risks to public authorities and populations.

The PolEASIA project is based on an ambitious approach combining observations and modeling, linking the local and global scales. An inverse modeling approach combining satellite observations and regional modeling will make it possible to derive up-to-dated, optimized and highly-resolved (1/4 degree, monthly)inventories of NOx and non-methane hydrocarbons emissions on a 10-year basis. A multi-scale approach combining satellite observations, in situ and simulations of chemistry transport models will allow us to characterize the distribution of pollutants, their interannual-to-daily variability and their trends. Specific studies will be carried out to quantify the role of different processes (emissions, transport, chemical transformation) driving the observed pollutant distributions. A particular attention will be paid to determining the natural and anthropogenic contribution of Asian pollution. The impact of Chinese pollution will be approached from several angles. The consequences of transboundary and transcontinental transport of pollutants on regional and global chemical composition will be determined using satellite observations and simulations. Health impact assessment methods coupled with simulations will estimate the long-term impact of pollutant exposure (ozone and PM2.5) on mortality from cardiovascular and respiratory diseases. In addition, the radiative forcing of the climate induced by short-lived species such as ozone and the different types of aerosols will be assessed from simulations for present conditions and for future scenarios. Advances in the understanding of Asian pollution, particularly in terms of modeling and numerical methods such as inverse modeling, will support the development of an operational air quality forecasting system.

At this stage of the project, the various tools necessary for its realization are developped. One important achievement of this first phase is the finalization of the development of the PYVAR-CHIMERE emission inversion system for reactive species. Few variational inversion systems are available in the community. Once the system's performance has been assessed, PYVAR-CHIMERE will provide a state-of-the-art tool for inverse pollutant sources. A significant result of this early project’s stage is the ozone trends observed by the IASI satellite instrument in the lower troposphere. A negative trend is observed, especially in the Pekin and the Northern Plain region, starting in 2013 essentially and coinciding with the strong emission reductions of ozone precursors. Studies combining satellite observations, in situ surface measurements or sonde profile measurements, model simulations (CHIMERE, LMDZORINCA) are on-going to understand the reasons of this decrease.

In addition to the expected direct scientific impacts to achieve a better understanding and description of the Eastern Asian photochemical and particulate pollution and its evolution and to assess its trans-boundary, climate and health impacts, the project will contribute to - consolidate the position of the French researchers involved in the project in the competitive research area concerning Chinese pollution and its impacts, especially by strengthening and by developing the collaborations with Asian partners - the improvements in numerical models achieved within the project that will benefit to a large scientific community. This is particularly the case for the CHIMERE model, which is labelled as a “national tool” by CNRS and has a large user group. The developments and improvements made within the project will also indirectly support the European Copernicus services as CHIMERE is part of the Atmospheric Services of Copernicus.

The project and initial results were presented at various international conferences (e.g. SFJWS2016, EGU2017).

Air pollution in East Asia and especially in China is an outstanding issue. The rapid economic development and urbanization during the last decades resulted in rising pollutant emissions leading to the largest pollutant concentrations in the world, largely exceeding the recommended outdoor air pollutant thresholds from the World Health Organization (WHO) for the major pollutants (ozone, PM2.5, and PM10). This pollution causes severe health problems increasing cardiovascular and respiratory diseases and premature mortality, and reduces population welfare (e.g. closure of transportation infrastructure due to lack of visibility). Robust monitoring and forecasting systems associated with downstream services providing comprehensive risk indicators are highly needed for public authorities to establish efficient pollution mitigation strategies and for populations to take preventive actions to preserve their health and welfare. In addition, a precise evaluation of the present and future impacts of Chinese pollutant emissions is of importance to quantify: first, the consequences of pollutants export on atmospheric composition and air quality all over the globe; second, the additional radiative forcing induced by the emitted and produced short-lived climate forcers (ozone and aerosols); third, the long-term health consequences of pollution exposure. To achieve this, a detailed understanding of sources of East Asian pollution is necessary.
Building on a ambitious synergistic approach combining observations and modeling to bridge the scales from local to global, the PolEASIA project aims at a better documentation and quantification of the sources and the distribution of the major pollutants (such as ozone and aerosols), and of their past, present and future evolution. Inverse modeling coupling satellite observations and regional modeling will be applied to derive highly resolved (monthly, ¼ of degree) optimized inventories of NOx and NMHC (non methane hydrocarbons) emissions over China for a decade. A multi-scale approach coupling innovative satellite observations, in situ measurements and chemical transport model simulations will be developed to characterize the spatial distribution, the interannual to daily variability and the long-term trends of the major pollutants (ozone and aerosols) over East Asia. Specific studies will be conducted to quantify the role of the different processes (emissions, transport, chemical transformation) explaining the observed pollutant distributions. A particular attention will be paid to assess the natural and anthropogenic contributions to Eastern Asian pollution.
The major impacts of Chinese pollution will be assessed. The consequences of the long-range transport of pollutants on regional and global atmospheric composition will be determined using both satellite observations and model simulations. Health Impact Assessment (HIA) methods coupled with model simulations will be used to estimate the long-term impacts of exposure to pollutants (PM2.5 and ozone) on cardiovascular and respiratory mortality. In addition, the radiative forcing of short-lived species (such as ozone and aerosols) will be derived from present-day simulations and simulations under future emission scenarios.
Progress made with the understanding of pollutant sources, especially in terms of modeling of pollution over East Asia and advanced numerical approaches such as inverse modeling will serve the development of an efficient and marketable forecasting system for regional outdoor air pollution. Additional modules will be coupled with the forecasting system including end-user friendly applications to provide comprehensive indices for health and visibility risks to public authorities and populations. The performances of this upgraded forecasting system will be evaluated and promoted to ensure a good visibility of the French technology.

Project coordination

Gaëlle Dufour (Laboratoire Interuniversitaire des Systèmes Atmosphériques)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

CRAES Chinese Research Academy of Environmental Sciences
PKU Peking University
ARIA ARIA Technologies
IAP Institute of Atmospheric Physics - Chinese Academy of Sciences
LISA Laboratoire Interuniversitaire des Systèmes Atmosphériques
LSCE Laboratoire des Sciences du Climat et de l'Environnement

Help of the ANR 459,803 euros
Beginning and duration of the scientific project: September 2015 - 48 Months

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