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Diurnal patterns in ambient PM2.5 exposure over India using MERRA-2 reanalysis data
Atmospheric Environment ( IF 5 ) Pub Date : 2020-12-31 , DOI: 10.1016/j.atmosenv.2020.118180
Kunal Bali , Sagnik Dey , Dilip Ganguly

Modeling of ambient PM2.5 exposure has improved in recent years with the application of satellite data, but in India, where the ground-based measurements are still inadequate, satellite-based assessment cannot provide temporal continuity. In this work, we analyze MERRA-2 (Modern-Era Retrospective analysis for Research and Applications) reanalysis aerosol products to estimate PM2.5 at an hourly scale over India to fill the temporal sampling gap. MERRA-2 PM2.5 calibrated using reference-grade monitors from the Central Pollution Control Board (CPCB) network show a statistically significant (at 95% CI) correlation (r = 0.9) against coincident in-situ measurements. Analyzing 18-years (2000–2017) data, we report the first detailed account of multi-year ambient PM2.5 diurnal patterns in India. Diurnal amplitude is found to be quite large (>30 μg m−3) in the Indo-Gangetic Basin (IGB) and western arid regions. We find a decrease in ambient PM2.5 over the western dust source region and an increase over the parts of IGB and central India, primarily in the morning and evening hours. The annual trend is strongly governed by the trend during the dry season (October–February), attributed to a combination of the changing emission and meteorology. Our results suggest that the satellite-based exposure estimates that typically represent late morning to early afternoon hours are usually lower than the 24-h average exposure in most parts of India. Therefore, we call for the integration of reanalysis data that provide better temporal resolution with satellite data that provide better spatial resolution to further improve exposure estimates in data void regions like India for air quality studies.



中文翻译:

使用MERRA-2再分析数据,印度环境PM 2.5暴露的日变化

近年来,随着卫星数据的应用,改善了PM 2.5暴露环境的建模,但是在印度,基于地面的测量仍然不够,基于卫星的评估无法提供时间连续性。在这项工作中,我们分析了MERRA-2(研究和应用的现代时代回顾性分析)再分析气溶胶产品,以估计印度每小时的PM 2.5来填补临时采样空白。MERRA-14:00 2.5使用参考级监视从中央污染控制委员会校准(CPCB)网络显示出统计学显著(95%CI)的相关性(ř = 0.9),同时进行原位测量。通过分析18年(2000-2017年)的数据,我们报告了印度多年环境PM 2.5昼夜模式的第一个详细说明。在印度恒河盆地(IGB)和西部干旱地区,日振幅被发现很大(> 30μgm -3)。我们发现环境PM 2.5降低了主要在早晨和傍晚时分,在西部粉尘源地区以及IGB和印度中部的部分地区都有所增加。年度趋势在很大程度上受干旱季节(10月至2月)的趋势支配,这归因于不断变化的排放和气象学。我们的结果表明,通常代表从清晨到午后时间的基于卫星的照射量估计值通常低于印度大部分地区的24小时平均照射量。因此,我们呼吁将能够提供更好时间分辨率的再分析数据与提供更好空间分辨率的卫星数据相集成,以进一步改善像印度这样的数据空缺地区的空气质量研究中的暴露估计。

更新日期:2021-01-29
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