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Investigating the spatial and temporal variation of aerosols and cloud parameters over South Asia using remote sensing

Malik Mahnoor, Tariq Salman, ul Haq Zia

Acta Geophysica

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2024

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Vol. 72, no. 2

1413--1438

EN

The most important component in determining the spatiotemporal distribution of aerosol at local and regional levels is aerosol optical depth (AOD). In this study, data has been obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Aqua satellite to examine spatiotemporal variations in AOD and their effects on the Angstrom Exponent (AE), and clouds parameters, namely cloud fraction, cloud optical thickness, cloud top pressure, cloud top temperature, ice cloud water path, liquid cloud water path, ice cloud effective radius, and liquid cloud effective radius over South Asia from July 2002 to July 2021. The highest values of AOD (0.53-0.7) were observed in the Indo-Gangetic basin (IGB) region over South Asia. The value of AOD of 0.7 is observed in the IGB region during summer. The 0.2 AOD value is observed in winter. The highest mean AOD (0.63 ± 0.09) observed in Bangladesh is due to the noteworthy increase in agricultural activities. The negative correlation between AOD and AE was noticed in Karachi (-0.24), Lahore (-0.04), Rawalpindi (-0.08), Mumbai (-0.03), Kathmandu (-0.49), Colombo (-0.19), and in Kabul (-0.51). A positive correlation is observed in Delhi (0.21), Bangalore (0.09), and Dhaka (0.17).

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Impact of meteorological parameters on aerosol optical depth and particulate matter in Lahore

Ur Rehman Zahid, Tariq Salman, ul Haq Zia, Khan Muhammad

Acta Geophysica

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2024

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Vol. 72, no. 2

1377--1395

EN

Particulate pollution has become one of the major issues in the mega-cities of Pakistan. As with the increase in rapid urbanization, poor air quality, climate change, and health-related issues are increasing gradually in Lahore. Therefore, the implications for the variability of air pollution need to be better understood for the improvement of air quality. So, in this article, we used aerosol robotic network (AERONET) and moderate resolution imaging spectroradiometer (MODIS) datasets along with the variability of different meteorological parameters (temperature, wind speed, relative humidity, dew point, and sea level pressure) over Lahore during 2006 to 2022. Moreover, the multi-linear regression model is used to analyse the linear relation of AERONET-retrieved aerosol optical depth (AOD) and particulate matter (PM2.5) with MODIS-retrieved AOD during the time period. Both AOD and PM2.5 increase gradually throughout the time period. AERONET-retrieved AOD showed a significant variability during the time period where each meteorological parameter gives a significant value (p < 0.05) except pressure (p > 0.05). The AERONET-retrieved AOD and PM2.5 give a strong positive value (0.78 and 0.63) of the coefficient of correlation. Seasonally, the value of the coefficient of correlation is observed high during summer (0.92) followed by autumn, spring, and winter. Considering the outcomes of this study, different methods like using better quality of fuel, use of public transport, plantation of trees, etc., can be employed to reduce air pollution.

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Analysis of air quality due to the eruption of La Palma using remote sensing

Yaqoob Tayyba, Tariq Salman, Bashir Iqra, ul Haq Zia

Acta Geophysica

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2024

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Vol. 72, no. 2

1397--1411

EN

Aerosols erupted from volcanoes may significantly alter climate because they can impact cloud dynamics, radiation budget, and tropospheric chemistry. The optical and physical characteristics of the Spatio-temporal variation of aerosols and gases' impact on the atmosphere during the recent La Palma eruption have been examined in the current paper from 19 September to 31 October 2021. The result shows that before the La Palma eruption, the AOD value was 0.1 showing a clear sky. However, after the eruption daily mean AOD reached the highest values of 0.7 and 0.56, showing that La Palma had high aerosol loading when the eruption occurred. The 0.4 value Aerosol index was observed. The coarse mode aerosols contributed more to the overall aerosol load than fine mode aerosols, confirming their existence above La Palma. Analysis revealed that mixed aerosols were present over La Palma. Due to the powerful ash plume's ability to scatter sunlight, the high value of Single-Scattering Albedo (~ 0.99) was detected. The maximum concentration of SO2, HCHO, NO2, O3, and CO was found to be 60 mmol/m2, 120 gmol/m2, 70 gmol/m2, 129 mmol/m2, and 50 mmol/m2, respectively, over the La Palma region. The ash plume's trajectory by the forward trajectory and the Hybrid Single Particle Lagrangian Integrated Trajectory dispersion model showed the plume moving in the southwest direction.