Dimitris G. Kaskaoutis

TL;DR: The lockdown of anthropogenic activities due to COVID-19 has led to a notable decrease in AOD over SEA and in the pollution outflow over the oceanic regions, while a significant decrease in tropospheric NO2 was observed over areas not affected by seasonal biomass burning.

Abstract: Aerosol emissions from biomass burning are of specific interest over the globe due to their strong radiative impacts and climate implications. The present study examines the impact of paddy crop residue burning over northern India during the postmonsoon (October–November) season of 2012 on modification of aerosol properties, as well as the long-range transport of smoke plumes, altitude characteristics, and affected areas via the synergy of ground-based measurements and satellite observations. During this period, Moderate Resolution Imaging Spectroradiometer (MODIS) images show a thick smoke/hazy aerosol layer below 2–2.5 km in the atmosphere covering nearly the whole Indo-Gangetic Plains (IGP). The air mass trajectories originating from the biomass-burning source region over Punjab at 500 m reveal a potential aerosol transport pathway along the Ganges valley from west to east, resulting in a strong aerosol optical depth (AOD) gradient. Sometimes, depending upon the wind direction and meteorological conditions, the plumes also influence central India, the Arabian Sea, and the Bay of Bengal, thus contributing to Asian pollution outflow. The increased number of fire counts (Terra and Aqua MODIS data) is associated with severe aerosol-laden atmospheres (AOD500 nm > 1.0) over six IGP locations, high values of Angstrom exponent (>1.2), high particulate mass 2.5 (PM2.5) concentrations (>100–150 µgm−3), and enhanced Ozone Monitoring Instrument Aerosol Index gradient (~2.5) and NO2 concentrations (~6 × 1015 mol/cm2), indicating the dominance of smoke aerosols from agricultural crop residue burning. The aerosol size distribution is shifted toward the fine-mode fraction, also exhibiting an increase in the radius of fine aerosols due to coagulation processes in a highly turbid environment. The spectral variation of the single-scattering albedo reveals enhanced dominance of moderately absorbing aerosols, while the aerosol properties, modification, and mixing atmospheric processes differentiate along the IGP sites depending on the distance from the aerosol source, urban influence, and local characteristics.

TL;DR: In this article, the authors analyzed the aerosol characteristics, dust loading and air quality over the Sistan region in South-West Asia, and showed that large quantities of transported dust that strongly depend on the duration of the dust events, and secondarily, on the wind speed and distance from the source region.

TL;DR: In this paper, a time series of Indian geostationary satellite KALPANA-1 Very High Resolution Radiometer (VHRR) together with ground observations are used to analyze the temporal variation of the dust event that occurred from 19 to 24 February 2008 with the strongest intensity on 22 February.

TL;DR: In this article, the spectral curvature of the Angstrom exponent was taken into account in the second-order polynomial fit to the plotted AOD versus the logarithm of wavelength, and the second derivative of α. The results reveal important features which can be used for better discriminating between different aerosol types.