The MUlti-SpEctral, MUlti-SpEcies, MUlti-SEnsors (MUSES) Retrievals from the EOS to the Suomi-NPP Era

Knowing the vertical distribution of O3 concentrations is thus crucial for studies of air quality, its effects on human health and vegetation, and the natural and anthropogenic contributions to ozone regional climate forcing. Carbon monoxide is a chemical precursor of greenhouse gases CO2 and tropospheric O3, and is also an ideal tracer of transport processes due to its medium life time (weeks to months). The Aqua-AIRS and Aura-OMI instruments in the "A-Train", CrIS and OMPS instruments on the Suomi-NPP, and TROPOMI aboard the Sentinel 5 precursor have the potential to provide the synoptic chemical/dynamical context for O3 necessary to quantify long-range transport at global scales and to provide an anchor to the near-term constellation of geostationary sounders: NASA TEMPO, ESA Sentinel 4, and the Korean GEMS. We introduce the MUSES retrieval algorithm, which ingests panspectral observations across multiple platforms in a non-linear optimal estimation framework. MUSES incorporates advances in remote sensing science developed during the EOS era including rigorous error analysis diagnostics and observation operators needed for trend analysis, climate model evaluation, and data assimilation. We present joint tropospheric O3 retrievals from AIRS/OMI and CrIS/OMPS for the KORUS-AQ campaign period. We also demonstrate the potential of joint carbon monoxide profiles from CrIS/ TROPOMI. These results indicate that ozone can be retrieved with 2 degrees of freedom for signal (dofs) in the troposphere, which is similar to TES. Joint CO profiles have dofs similar to the MOPITT multispectral retrieval but with higher spatial resolution and coverage. Consequently, multispectral retrievals show promise in providing continuity with EOS observations and pave the way towards a new advanced atmospheric composition constellation.