Provençal Simon, Kishcha Pavel, da Silva Arlindo M, Elhacham Emily, Alpert Pinhas
Département de géographie, Université Laval, Quebec City, Quebec, Canada.
Department of Geosciences, Tel Aviv University, Tel Aviv, Israel.
Urban Clim. 2017 Jun;20:168-191. doi: 10.1016/j.uclim.2017.04.001. Epub 2017 Apr 26.
NASA recently extended the Modern-Era Retrospective Analysis for Research and Application (MERRA) with an atmospheric aerosol reanalysis which includes five particulate species: sulfate, organic matter, black carbon, mineral dust and sea salt. The MERRA Aerosol Reanalysis (MERRAero) is an innovative tool to study air quality issues around the world for its global and constant coverage and its distinction of aerosol speciation expressed in the form of aerosol optical depth (AOD). The purpose of this manuscript is to apply MERRAero to the study of urban air pollution at the global scale by analyzing the AOD over a period of 13 years (2003-2015) and over a selection of 200 of the world's most populated cities in order to assess the impacts of urbanization, industrialization, air quality regulations and regional transport which affect urban aerosol load. Environmental regulations and the recent global economic recession have helped to decrease the AOD and sulfate aerosols in most cities in North America, Europe and Japan. Rapid industrialization in China over the last two decades resulted in Chinese cities having the highest AOD values in the world. China has nevertheless recently implemented emission control measures which are showing early signs of success in many cities of Southern China where AOD has decreased substantially over the last 13 years. The AOD over South American cities, which is dominated by carbonaceous aerosols, has also decreased over the last decade due to an increase in commodity prices which slowed deforestation activities in the Amazon rainforest. At the opposite, recent urbanization and industrialization in India and Bangladesh resulted in a strong increase of AOD, sulfate and carbonaceous aerosols in most cities of these two countries. The AOD over most cities in Northern Africa and Western Asia changed little over the last decade. Emissions of natural aerosols, which cities in these two regions tend to be mostly composed of, don't tend to fluctuate significantly on an annual basis.
美国国家航空航天局（NASA）最近通过一项大气气溶胶再分析扩展了“现代时代回顾分析用于研究和应用”（MERRA），该再分析包括五种颗粒物：硫酸盐、有机物、黑碳、矿物尘埃和海盐。MERRA气溶胶再分析（MERRAero）是一种创新工具，因其全球范围的持续覆盖以及以气溶胶光学厚度（AOD）形式体现的气溶胶物种区分，可用于研究全球各地的空气质量问题。本论文的目的是通过分析13年（2003 - 2015年）期间以及从世界上200个人口最密集城市中选取的部分城市的AOD，将MERRAero应用于全球尺度的城市空气污染研究，以评估城市化、工业化、空气质量法规和区域传输对城市气溶胶负荷的影响。环境法规和近期的全球经济衰退有助于降低北美、欧洲和日本大多数城市的AOD和硫酸盐气溶胶。过去二十年中国的快速工业化导致中国城市拥有世界上最高的AOD值。不过，中国最近实施了排放控制措施，在中国南方的许多城市已初见成效，过去13年这些城市的AOD大幅下降。南美洲城市的AOD主要由含碳气溶胶主导，在过去十年中也有所下降，这是由于商品价格上涨减缓了亚马逊雨林的森林砍伐活动。相反，印度和孟加拉国近期的城市化和工业化导致这两个国家大多数城市的AOD、硫酸盐和含碳气溶胶大幅增加。在过去十年中，北非和西亚大多数城市的AOD变化不大。这两个地区的城市大多由自然气溶胶排放构成，其排放量在年度基础上往往不会有显著波动。
