Aerosol Optical Depth Index Research Articles

Remote Sensing Surveillance of NO2, SO2, CO, and AOD along the Suez Canal Pre- and Post-COVID-19 Lockdown Periods and during the Blockage

This study investigates the impact of the COVID-19 pandemic and the Ever Given ship blockage on the air quality in Suez Canal region. Nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon monoxide (CO), and aerosol optical depth (AOD) were studied, and data were obtained from satellite instruments. The study compared monthly average data for 2020, 2021, and 2022 with a baseline period of 2017–2019 to investigate the pandemic’s effect. The study also analyzed the corresponding period of the canal blockage to identify its impact on air pollution levels. The pandemic had a significant role in decreasing NO2 by 2.5 × 1014 molecule/cm2 and SO2 by 0.05 DU due to reduced car traffic and industrial activities. A reduction in AOD by 20% and CO concentration in the range from 3.5% to 4.7% was reported in early 2020. During the blockage, NO2 and SO2 levels decreased by 14.4% and 66.0%, respectively, while CO and AOD index increased by 12.68% and 51.0%, respectively. The study concludes that the containment measures during the pandemic had a positive impact on the environment, which shows how the reduction in the anthropogenic activities, especially industrial and transportation activities, have improved the air quality. Thus, stricter actions are needed to protect the environment; for example, the transition towards the using of electric vehicle is necessary, which is part of Egypt’s strategy to transition towards a green economy. The government should also adopt a policy to trade carbon emissions reduction certificates to help reduce air pollution.

Standard aerosol optical depth index and application in the Middle East countries

Middle East is one of the most aerosol subjected region of the world. The records of aerosol optical depth (AOD) from 2003 to 2016 inclusive are investigated standard aerosol optical depth index (SAODI) providing verbal and numerical interpretations about the AOD records at Syria-Iraq northern, west Iraq, Iraq marshes, Iran Ahwaz and Ilam regions in addition to Saudi Arabia and United Arab Emirates. AOD records at different countries have different probability distribution functions (PDF), and the criteria of the average AOD plus 1, 2, 3 and 4 times the standard deviation of AOD record methodology as available in the literature does not provide a common footing for AOD assessment. Application of innovative trend analysis of the aerosol records indicated that although trends have rather small slopes, but in the Marshes, Ahwaz and Ilam locations there are decreasing trends, whereas in other locations the trends have increasing tendency.

Spatiotemporal characteristics of TOMS-based dust aerosol optical depth in northern China during 1978–2005

Using the Total Ozone Mapping Spectrometer (TOMS) data from the National Aeronautics and Space Administration (NASA) earth satellites, the Aerosol Optical Depth (AOD) as indicated by AOD Index (AI) for the period 1978–2005 is analyzed for northern China. The spatial distribution of annual mean AI has the largest values in the desert regions of northwestern China, such as southern Xinjiang Taklimakan Basin, western Gansu and Qinghai’s Qaidam Basin. Large values are found in western Inner Mongolia, the Jogger Basin, and north of the Loess Plateau, as well as in the North China and Northeast China Plains. In Northern China, the AI of spring and summer is larger than in other seasons. The large AI values in spring register the most extensive coverage, but the AI values in regions affected by the Asian monsoon experience a significant decrease during the summer season. The lowest AI values generally occur in autumn in North and Northeast China, but they appear in winter in the northwestern arid region. Overall, the analysis results using TOMS AI data well reflect the spatiotemporal characteristics of dust aerosol as reported previously based on the dust weather observation data, with greater consistency seen in northwestern arid and semi-arid regions. It is also realized that the TOMS AI data are potentially useful for estimating atmospheric mineral aerosol deposition flux in northern China in order to better understand the formation and evolution of China loess in the Quaternary.