Toward a Reanalysis of Stratospheric Ozone for Trend Studies: Assimilation of the Aura Microwave Limb Sounder and Ozone Mapping and Profiler Suite Limb Profiler Data

Compatibility of the stratospheric ozone profile data from the Ozone Mapping and Profiler Suite Limb Profiler (OMPS-LP) and the Microwave Limb Sounder (MLS) is assessed in the context of a continuity requirement for future reanalyses. A methodology for the assimilation of OMPS-LP data into the Goddard Earth Observing System data assimilation system with a stratospheric chemistry module is developed. It is demonstrated that a simple homogenization technique significantly reduces the bias between OMPS-LP and MLS analyses. With the homogenization applied, the mean difference between the two analyses is within 3% and the difference standard deviation within 10%, consistent with the estimated uncertainties of the satellite ozone data. Larger differences are seen in the tropical lower stratosphere. The MLS and OMPS-LP assimilation experiments agree very well with independent data from ozonesondes and the Atmospheric Chemistry Experiment Fourier Transform Spectrometer. Heterogeneous ozone depletion during polar spring in both hemispheres as well as ozone transport during the 2016 quasi-biennial oscillation disruption event are realistically represented in both analyses. This work establishes a step toward achieving continuity of the post-2004 ozone record in future reanalyses, necessary for trend and long-term ozone variability studies, although further development is needed to address a drift in the OMPS-LP ozone data.