Overview and update of the SPARC Data Initiative: comparison of stratospheric composition measurements from satellite limb sounders

Abstract. The Stratosphere-troposphere Processes and their Role in Climate (SPARC) Data Initiative (SPARC, 2017) performed the first comprehensive assessment of currently available stratospheric composition measurements obtained from an international suite space-based limb sounders. initiative's main objectives were (1) to assess state data availability, (2) compile time series vertically resolved, zonal monthly mean trace gas aerosol fields, (3) perform a detailed intercomparison these series, summarizing useful information highlighting differences among datasets. datasets extend over region upper troposphere lower mesosphere (300–0.1 hPa) are provided on common latitude–pressure grid. They cover 26 different atmospheric constituents including gases primary interest, ozone (O3) water vapor (H2O), major long-lived (SF6, N2O, HF, CCl3F, CCl2F2, NOy), with intermediate lifetimes (HCl, CH4, CO, HNO3), shorter-lived important chemistry nitrogen-containing species (NO, NO2, NOx, N2O5, HNO4), halogens (BrO, ClO, ClONO2, HOCl), other minor (OH, HO2, CH2O, CH3CN), aerosol. This overview SPARC introduces updated versions for extended period 1979–2018 provides satellite instruments included assessment: LIMS, SAGE I/II/III, HALOE, UARS-MLS, POAM II/III, OSIRIS, SMR, MIPAS, GOMOS, SCIAMACHY, ACE-FTS, ACE-MAESTRO, Aura-MLS, HIRDLS, SMILES, OMPS-LP. It describes Initiative's top-down climatological validation approach compare based which bounds relative inter-instrument biases how well able capture geophysical features stratosphere. An update previously published evaluations O3 H2O is provided. In addition, example methane (CH4), carbon monoxide (CO), set nitrogen reactive family (NOy), hydroperoxyl (HO2) presented. results highlight quality, strengths weaknesses, representativeness As summary, current our knowledge variability overall consistency between such, can serve as atlas or reference during “golden age” sounding. each instrument publicly accessible via Zenodo archive (Hegglin et al., 2020).