Merging the SAGE II and OSIRIS Stratospheric Aerosol Records

Abstract:

Since the end of the SAGE II mission several instruments with differing measurement techniques, wavelength ranges, and geographic coverage have taken up the mantle of retrieving stratospheric aerosols. Each of these instruments provides unique information on the state of aerosols; however, due to the difference in techniques there is no consistent, long-term record of global, stratospheric aerosols spanning the previous three decades. One of the instruments currently taking measurements is the Optical Spectrograph and Infrared Imaging System which was launched in 2001 and measures limb scatter radiance profiles in the UV to NIR range. OSIRIS produces hundreds of measurements a day covering the majority of the sunlit portion of the globe, providing near global coverage of stratospheric aerosols.

This work merges the SAGE II and OSIRIS aerosol data products to produce a 30 year, near global, 525nm stratospheric aerosol record with approximately 2 km vertical resolution. Agreement between the two datasets is typically within 10% in the bulk of the stratosphere, however saturation of the OSIRIS instrument at lower altitudes, especially in the tropical UTLS, likely leads to low biases in the aerosol optical depth in this region. To correct these issues it would beneficial to incorporate this merging with other instruments such as CALIOP and GOMOS, which do not suffer from this issue, but would benefit from inclusion of the OSIRIS data in other regions.