Evaluation of the New CALIOP Stratospheric Aerosol Subtypes

The space-borne lidar CALIOP has been observing the vertical profiles of tropospheric and stratospheric aerosols since 2006. In addition to providing estimates of aerosol extinction, the CALIOP level 2 algorithms also report aerosol subtype information, whereby tropospheric aerosol layers are classified as one of several subtypes depending on the measured optical properties. This information is valuable for discriminating between anthropogenic versus natural sources and for estimating radiative impacts. Previous versions of CALIOP data products only reported aerosol subtypes for layers detected below the tropopause. However, a new set of stratospheric aerosol subtypes have been introduced in the most recent release of CALIOP level 2 data products (version 4). These new subtypes are able to classify volcanic ash, volcanic sulfate, and elevated smoke that have been injected above the tropopause. This presentation will provide an initial evaluation of the accuracy of the stratospheric aerosol subtyping algorithm for correctly classifying volcanic aerosol and smoke. Specific events will be evaluated, including: volcanic plumes from Nabro and Puyehue-Cordón Caulle in 2011, Kasatochi in 2008, and smoke plumes from extreme fire events such as the Australian bush fire in 2009 and the North American wildfires in 2017. The stratospheric aerosol subtyping classification accuracy will be evaluated using case studies and evaluated statistically in order to assess the performance of the algorithm.