A Trend Analysis of Global and Regional CALIOP-Based Aerosol Vertical Distribution

Past studies have examined trends in satellite-derived observations of aerosol optical depth (AOD) through the use of passive radiometric sensors like Moderate Resolution Imaging Spectroradiometer (MODIS) and Multi-angle Imaging Spectroradiometer (MISR). However, because passively-sensed AOD is column-integrated, the altitude at which significant perturbations occur to mean climatological profiles for aerosol particle presence cannot be resolved. Yet knowledge of aerosol loading trends, as a function of altitude, is pivotal to increasing our understanding of various aerosol-related issues, including atmospheric heating rates and aerosol-cloud interactions. An active sensor, like the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), is currently the only instrument capable of detecting aerosol vertical distribution on a global scale. While existing CALIOP-based climatological studies report the mean state of aerosol vertical distribution, we focus on studying trends of CALIOP-derived AOD at several altitudes within the atmospheric column through the use of seven and a half years (June 2006-December 2013) of CALIOP aerosol particle profile measurements. Quality assurance procedures are carefully evaluated, and both global and regional analyses are presented.