Global changes in Aerosols Optical, Physical, and Morphological properties obtained using 20 years of Multi-sensor measurements.

It is well known that one of the main drivers of Earth's radiation budget and climate change is the drastic changes in the aerosol emissions. In this regard, numerous studies have been carried out to examine the trends in the rapidly changing aerosol loading through the total Aerosol Optical Depth (AOD). But very few investigations have acknowledged its long-term implications through the combined optical, physical, and morphological properties of the aerosols, as total AOD is a combination of the aerosols size, shape, and optical properties. To accomplish this on a global scale, multi-satellite and reanalysis measurements are used and a detailed comparison has been made prior with the ground-based observations as well. However, the long-term implications are estimated using the multivariate regression model in which contributions from the naturally occurring weather phenomenon such as Solar Cycle, Quasi-Biennial oscillations, and El-Niño southern oscillations, are isolated from the datasets. With the implementation of this approach on nearly two decades (2001-2020) of multisource datasets, we tried to relate the contribution of each of the varying aerosol properties to the changing total AOD trends across the globe. Region-wise analysis has shown that the decrease (increase) in the total AOD trends observed over North-Eastern America, South America, and Europe (Indian) regions are mainly in connection with the decline (incline) in the fine-mode and scattering aerosols. Interestingly, the Indo-Gangetic Plain region of India, where high total AOD trends are observed, has seen a plausible decrease (slight) in its absorbing, non-spherical, and coarse-mode aerosols in the recent years. This study also details the region-wise response accompanying the implementation of stringent mitigation strategies to ensure accurate quantification of the changing aerosol patterns in the atmosphere.