Revisiting Stratospheric Aerosol Climatology for the Post-SAGEII Era Using Space-Based Measurements

A robust stratospheric aerosol climatology is important as many global climate models (GCMs) make use of observed aerosol properties to prescribe aerosols in the stratosphere. As a part of the Coupled Model Intercomparison project version 6 (CMIP6), a global space-based stratospheric aerosol climatology (GloSSAC) was recently created [Thomason et al., 2017]. Several space-based measurements were used to create GloSSAC, starting from 1979. These primarily constitute data from the Stratospheric Aerosol Gas Experiment (SAGE) series of satellites until the end of SAGE II measurements in August 2005. The measurements since August 2005 (post-SAGEII era), however, have been mostly depending on satellites that use the limb scatter (LS) technique. The stratospheric aerosol data in the post-SAGEII era in GloSSAC are represented by measurements from Optical Spectrograph and InfraRed Imager System (OSIRIS) and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). However, at the transition of SAGE II-OSIRIS data in August 2005, the two datasets tend to differ in the mid-high latitudes particularly following the Manam volcanic eruption in January 2005, where OSIRIS has overlap measurements with SAGE II. This enhancement of aerosol in the lower stratosphere seems persistent even years after the eruption in January 2005. Here, we revisit the aerosol climatology in the post-SAGEII era primarily by using OSIRIS level 2 and CALIPSO version 4.10 data. We also investigate for any cloud contamination in OSIRIS level 2 data in particular, which may have caused apparent enhancement in the aerosol extinction particularly near the tropopause. SAGEIII-ISS data is also used to extend the climatology to the present and to test the approach used to correct OSIRIS/CALIPSO data for the post-SAGEII era.