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DOI	10.5194/acp-22-15703-2022
	Aerosol optical depth regime over megacities of the world
	Papachristopoulou, Kyriakoula; Raptis, Ioannis-Panagiotis; Gkikas, Antonis; Fountoulakis, Ilias; Masoom, Akriti; Kazadzis, Stelios
发表日期	2022
ISSN	1680-7316
EISSN	1680-7324
起始页码	15703
结束页码	15727
卷号	22 期号:24 页码:25
英文摘要	Currently, 55 % of the world's population resides in urban areas and this number is projected to increase to 70 % by 2050. Urban agglomerations with a population over 10 million, characterized as megacities, are expected to be more than 100 by 2100. Such large concentrations of population could boost creativity and economic progress, but also raises several environmental challenges such as air quality degradation. In this study, we investigate the spatial and temporal variability of urban aerosol state of 81 cities with a population over 5 million, relying on daily satellite-based aerosol optical depth (AOD) retrievals, derived at fine spatial resolution (0.1 degrees x 0.1 degrees), over an 18-year period spanning from 2003 to 2020. According to our results, the lowest long-term mean AOD values worldwide were found in European and American cities (from 0.08 to 0.20). For almost all African and Asian cities, mean AOD ranged from 0.25 up to 0.90, but a considerable dust aerosol contribution (up to 70 %) was found for some of them with associated mean dust optical depth (DOD) values reaching up to 0.4. Mostly Chinese and Indian cities tend to have higher mean AOD values in the areas surrounding their center, while the opposite was found for most of the cities in the rest of the world. High intraannual AOD variability was revealed for the eastern American cities, while lower values were found in Chinese, eastern Indian and the eastern Mediterranean cities. During the study period, statistically significant negative AOD decadal trends were found for East Asian, European and North American cities, with the greatest decrease of -0.1 to -0.3 per decade recorded for the Chinese cities, in which the maximum mean AODs (0.45-0.91) are observed. In most of the US cities, where low mean AOD < 0.17 was recorded, considerable declining AOD trends were found (-30 % to -50 % per decade). For the rest of Asian, African and South American cities, statistically significant AOD increase was found, with the greatest values of +0.07 to +0.16 per decade recorded for Indian cities. In Bengaluru (India), it is reported the lowest mean AOD value (0.2) and the maximum AOD increase (+69 %), which may be partially attributed to the population growth over the study period. The agreement of the satellite-derived AOD trends against those obtained from ground-based AERONET measurements was examined. For ground-based stations within the geographical limits of the contiguous urban area of the examined cities, a 0.93 correlation for the long-term means of AOD was found and similar to 75 % of the derived trends agreed in sign. It was found that the spatial homogeneity within the examined satellite domain and the location of the surface station were key factors that determined their agreement. The present study highlights the vital and essential contribution of spaceborne products to monitor aerosol burden over megacities of the planet towards fulfilling the United Nations Sustainable Development Goal of sustainable cities and communities, dealing with urban air quality.
学科领域	Environmental Sciences; Meteorology & Atmospheric Sciences
语种	英语
WOS研究方向	Environmental Sciences & Ecology ; Meteorology & Atmospheric Sciences
WOS记录号	WOS:000899167000001
来源期刊	ATMOSPHERIC CHEMISTRY AND PHYSICS
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/273844
作者单位	National & Kapodistrian University of Athens; Swiss Federal Institutes of Technology Domain; ETH Zurich
推荐引用方式 GB/T 7714	Papachristopoulou, Kyriakoula,Raptis, Ioannis-Panagiotis,Gkikas, Antonis,et al. Aerosol optical depth regime over megacities of the world[J],2022,22(24):25.
APA	Papachristopoulou, Kyriakoula,Raptis, Ioannis-Panagiotis,Gkikas, Antonis,Fountoulakis, Ilias,Masoom, Akriti,&Kazadzis, Stelios.(2022).Aerosol optical depth regime over megacities of the world.ATMOSPHERIC CHEMISTRY AND PHYSICS,22(24),25.
MLA	Papachristopoulou, Kyriakoula,et al."Aerosol optical depth regime over megacities of the world".ATMOSPHERIC CHEMISTRY AND PHYSICS 22.24(2022):25.