An 11-year global 3 D climatology and trends of aerosol optical depth using satellite data from CALIOP

Climate change is driven by several natural and anthropogenic factors and processes through the perturbation of the Earth’s and atmosphere’s energy budget [12]. Atmospheric aerosols, both natural and anthropogenic, remain one of the largest sources of uncertainty for climate change [1] with the aerosol vertical distribution being one of the causes of this uncertainty [23]. In the present work we present a global 3D climatology of aerosol optical depth (AOD) on a 2.50 x 2.50 horizontal and 500 m vertical resolution. The climatology is created using the CALIOP Level 2 Version 4.10 profile product, during both daytime and nighttime for an 11-year long period (2007-2017). The results reveal significant spatial variability, with larger AOD over the Northern Hemisphere than the Southern and over land than oceans. On a mean annual level, greater aerosol load is observed above East Asia, the Arabian and Sahara Deserts and the Indian Subcontinent. The bulk of the aerosol load is mostly confined in the boundary layer. The interannual trends of the AOD are also estimated. The results indicate statistically significant (at the 95% level) increasing AOD trend over India and statistically significant decreasing trends in East Asia and the Arabian Peninsula. Smaller, albeit mostly statistically significant, decreasing trends are also found over Europe, the eastern United States and parts of South America. Our results are also compared against corresponding data from the MODIS Aqua Dark Target Deep Blue combined product (collection 061, level 3). Preliminary results reveal that the interannual trends based on CALIOP and MODIS AOD are in generally good agreement.