Abstract
Abstract. We describe the construction of a continuous 38-year record of stratospheric aerosol optical properties. The Global Space-based Stratospheric Aerosol Climatology, or GloSSAC, provided the input data to the construction of the Climate Model Intercomparison Project stratospheric aerosol forcing data set (1979–2014) and we have extended it through 2016 following an identical process. GloSSAC focuses on the Stratospheric Aerosol and Gas Experiment (SAGE) series of instruments through mid-2005, and on the Optical Spectrograph and InfraRed Imager System (OSIRIS) and the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) data thereafter. We also use data from other space instruments and from ground-based, air, and balloon borne instruments to fill in key gaps in the data set. The end result is a global and gap-free data set focused on aerosol extinction coefficient at 525 and 1020 nm and other parameters on an “as available” basis. For the primary data sets, we developed a new method for filling the post-Pinatubo eruption data gap for 1991–1993 based on data from the Cryogenic Limb Array Etalon Spectrometer. In addition, we developed a new method for populating wintertime high latitudes during the SAGE period employing a latitude-equivalent latitude conversion process that greatly improves the depiction of aerosol at high latitudes compared to earlier similar efforts. We report data in the troposphere only when and where it is available. This is primarily during the SAGE II period except for the most enhanced part of the Pinatubo period. It is likely that the upper troposphere during Pinatubo was greatly enhanced over non-volcanic periods and that domain remains substantially under-characterized. We note that aerosol levels during the OSIRIS/CALIPSO period in the lower stratosphere at mid- and high latitudes is routinely higher than what we observed during the SAGE II period. While this period had nearly continuous low-level volcanic activity, it is possible that the enhancement in part reflects deficiencies in the data set. We also expended substantial effort to quality assess the data set and the product is by far the best we have produced. GloSSAC version 1.0 is available in netCDF format at the NASA Atmospheric Data Center at https://eosweb.larc.nasa.gov/. GloSSAC users should cite this paper and the data set DOI (https://doi.org/10.5067/GloSSAC-L3-V1.0).
Highlights
Since the discovery of the stratospheric aerosol layer, there has been a continuing interest in the role of stratospheric aerosol in chemistry and climate
We supplement Stratospheric Aerosol and Gas Experiment (SAGE) observations with a variety of other space-based observations as well as ground- and balloonbased observations. These merged data have formed a part of a number of well-known aerosol climatologies including the Goddard Institute for Space Studies (GISS) Stratospheric Aerosol Optical Thickness forcing data set (Sato et al, 1993) and more extensive sets reported in Thomason et al (1997b), Stenchikov et al (1998), Bauman et al (2003), SPARC (2006), and Arfeuille et al (2013)
We exclude any data below the highest altitude at which 1020 nm aerosol extinction coefficient exceeds 0.01 km−1 because of potential artifacts in SAGE II data at altitudes where the atmosphere is essentially opaque. Both Cryogenic Limb Array Etalon Spectrometer (CLAES) and Halogen Occultation Experiment (HALOE) flew aboard the Upper Atmosphere Research Satellite (UARS) and all UARS data are reported at pressure levels rather than altitude like SAGE II
Summary
Since the discovery of the stratospheric aerosol layer, there has been a continuing interest in the role of stratospheric aerosol in chemistry and climate. GloSSAC is most closely related to the Assessment of Stratospheric Aerosol Properties (ASAP; SPARC, 2006) and CMIP phase 5 data sets (for papers related to this data set see Vernier et al, 2011, Solomon et al, 2011, and Mills et al, 2016) and follows the same basic paradigm that produce those versions We build it primarily using space-based measurements by a number of instruments including the SAGE series, the Optical Spectrograph and InfraRed Imager System (OSIRIS; Rieger et al, 2015), the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO; Vernier et al, 2011), Cryogenic Limb Array Etalon Spectrometer (CLAES; Massie et al, 1996), and the Halogen Occultation Experiment (HALOE; Thomason, 2012).
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