38 research outputs found
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Recent ozone trends in the Chinese free troposphere: role of the local emission reductions and meteorology
International audienceAbstract. Free tropospheric ozone (O3) trends in the Central East China (CEC) and export regions are investigated for 2008–2017 using the IASI (Infrared Atmospheric Sounding Interferometer) O3 observations and the LMDZ-OR-INCA model simulations, including the most recent Chinese emission inventory. The observed and modelled trends in the CEC region are −0.07 ± 0.02 and −0.08 ± 0.02 DU yr−1, respectively, for the lower free troposphere (3–6 km column) and −0.05 ± 0.02 and −0.06 ± 0.02 DU yr−1, respectively, for the upper free troposphere (6–9 km column). The statistical p value is smaller to 0.01 for all the derived trends. A good agreement between the observations and the model is also observed in the region, including the Korean Peninsula and Japan and corresponding to the region of pollution export from China. Based on sensitivity studies conducted with the model, we evaluate, at 60 % and 52 %, the contribution of the Chinese anthropogenic emissions to the trend in the lower and upper free troposphere, respectively. The second main contribution to the trend is the meteorological variability (34 % and 50 %, respectively). These results suggest that the reduction in NOx anthropogenic emissions that has occurred since 2013 in China led to a decrease in ozone in the Chinese free troposphere, contrary to the increase in ozone at the surface. We designed some tests to compare the trends derived by the IASI observations and the model to independent measurements, such as the In-service Aircraft for a Global Observing System (IAGOS) or other satellite measurements (Ozone Monitoring Instrument (OMI)/Microwave Limb Sounder (MLS)). These comparisons do not confirm the O3 decrease and stress the difficulty in analysing short-term trends using multiple data sets with various sampling and the risk of overinterpreting the results
Identification et impact de la sarcopénie chez les patients en surpoids et obèses avec un carcinome à cellules rénales localisé.
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The unintended consequence of SO<sub>2</sub> and NO<sub>2</sub> regulations over China: increase of ammonia levels and impact on PM<sub>2,5</sub> concentrations
International audienceAir pollution reaching hazardous levels in many Chinese cities has been a major concern in China over the past decades. New policies have been applied to regulate an-thropogenic pollutant emissions, leading to changes in atmospheric composition and in particulate matter (PM) production. Increasing levels of atmospheric ammonia columns have been observed by satellite during recent years. In particular , observations from the Infrared Atmospheric Sounding Interferometer (IASI) reveal an increase of these columns by 15 % and 65 % from 2011 to 2013 and 2015, respectively , over eastern China. In this paper we performed model simulations for 2011, 2013 and 2015 in order to understand the origin of this increase and to quantify the link between ammonia and the inorganic components of particles: NH + 4(p) /SO 2− 4(p) /NO − 3(p). Interannual change of meteorology can be excluded as a reason: year 2015 meteorology leads to enhanced sulfate production over eastern China, which increases the ammonium and decreases the ammonia content, which is contrary to satellite observations. Reductions in SO 2 and NO x emissions from 2011 to 2015 of 37.5 % and 21 % respectively, as constrained from satellite data, lead to decreased inorganic matter (by 14 % for NH + 4(p) + SO 2− 4(p) + NO − 3(p)). This in turn leads to increased gaseous NH 3(g) tropospheric columns by as much as 24 % and 49 % (sampled corresponding to IASI data availability) from 2011 to 2013 and 2015 respectively and thus can explain most of the observed increase
The unexpected effect of SO2 and NO2 emission reductions over China: strong and rapid increase of atmospheric ammonia levels
info:eu-repo/semantics/nonPublishe