Brazil, one of the world’s fastest-growing economies, is the fifth most populous country and is experiencing accelerated urbanization. This combination of factors causes an increase in urban population that is exposed to poor air quality, leading to public health burdens. In this work, the Weather Research and Forecasting Model with Chemistry is applied to simulate air quality over Brazil for a short time period under three future emission scenarios, including current legislation (CLE), mitigation scenario (MIT), and maximum feasible reduction (MFR) under the Representative Concentration Pathway 4.5 (RCP4.5), which is a climate change scenario under which radiative forcing of greenhouse gases (GHGs) reach 4.5 W m⁻² by 2100. The main objective of this study is to determine the sensitivity of the concentrations of ozone (O₃) and particulate matter with aerodynamic diameter 2.5 µm or less (PM_2.5) to changes in emissions under these emission scenarios and to determine the signal and spatial patterns of these changes for Brazil. The model is evaluated with observations and shows reasonably good agreement. The MFR scenario leads to a reduction of 3% and 75% for O₃ and PM_2.5 respectively, considering the average of grid cells within Brazil, whereas the CLE scenario leads to an increase of 1% and 11% for O₃ and PM_2.5 respectively, concentrated near urban centers. These results indicate that of the three emission control scenarios, the CLE leads to poor air quality, while the MFR scenario leads to the maximum improvement in air quality. To the best of our knowledge, this work is the first to investigate the responses of air quality to changes in emissions under these emission scenarios for Brazil. The results shed light on the linkage between changes of emissions and air quality.

中文翻译：

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在巴西有代表性的浓度途径4.5情景下，空气质量对排放变化的短期响应

巴西是世界上增长最快的经济体之一，是第五大人口大国，并且正在经历加速的城市化进程。这些因素的综合作用导致暴露于空气质量差的城市人口增加，从而导致公共卫生负担。在这项工作中，将应用化学天气研究和预测模型在三个未来排放情景下（包括当前立法（CLE），缓解情景（MIT）和最大可行减少量（MFR））在短时间内模拟巴西的空气质量。 ）在代表浓度途径4.5（RCP4.5）下进行，这是一种气候变化情景，在该情景下温室气体（GHG）的辐射强迫达到4.5 W m ^-2到2100年。这项研究的主要目的是确定空气动力学直径为2.5 µm或更小的空气中的臭氧（O ₃）和颗粒物（PM _2.5）浓度在这些排放情景下的敏感性，并确定信号以及巴西这些变化的空间格局。该模型通过观察进行评估，并显示出良好的一致性。所述MFR场景导致减少3％和用于O- 75％₃和PM _2.5分别，考虑到平均内巴西网格单元，而CLE方案导致的增加的1％和11％氧气₃和PM _2.5分别集中在城市中心附近。这些结果表明，在三种排放控制方案中，CLE导致空气质量差，而MFR方案导致空气质量得到最大改善。据我们所知，这项工作是首次调查在这些排放情景下巴西的空气质量对排放变化的响应。结果揭示了排放物变化与空气质量之间的联系。