Assimilation of MLS and OMPS-Limb Profiler Ozone into GEOS-5

Stratospheric ozone is a key factor in the Earth's radiative budget, climate forcing and chemical composition of the atmosphere. It is, therefore, important to have accurate representation of its non-uniform and time-dependent concentrations on the global scale in reanalyses and operational weather prediction models. The Goddard Earth Observing System. Version 5 (GEOS-5) data assimilation system has been successful in producing realistic global maps of ozone from assimilation of retrieved profile data from the Microwave Limb Sounder (MLS) and total column observations from Ozone Monitoring Instrument (OMI), both flying on the EOS-Aura satellite. These two data sets are currently assimilated in the near-real-time GEOS-5 analyses, as well as in the latest reanalysis: the Modern Era Retrospective Analysis, version 2 (MERRA-2). The first part of this presentation demonstrates the quality of this assimilated data set, focusing on the realism of assimilated ozone and its flow-dependent inter-annual variability by comparing the product with independent data from ozonesondes.

One instrument on the Suomi National Polar-orbiting Partnership satellite, launched in late October 2011, is the Ozone Mapping and Profiler Suite – Limb Profiler (OMPS-LP). Daytime stratospheric ozone profiles can be retrieved from measurements of scattered solar radiation in the visible and ultraviolet bands. The vertical resolution is comparable to, or higher than, that of MLS. In the second part of the presentation we will show the results of assimilating OMPS-LP ozone data in comparison to the established MLS-based product. We will show the areas where the two analyses do and do not agree, discuss the underlying differences in the data from both instruments, and present a brief assessment of the OMPS-LP data in the context of assimilation. Implications for combining MLS and OMPS-LP ozone data in future reanalyses will be discussed.