On the extraction of wind information from the assimilation of ozone profiles in Météo–France 4-D-Var operational NWP suite

Abstract

Abstract. By applying four-dimensional variational dataassimilation (4-D-Var) to a combined ozone and dynamics Numerical Weather Prediction model (NWP), ozone observations generate wind increments through the ozonedynamics coupling. The dynamical impact of Aura/MLS satellite ozone profiles is investigated using Météo-France operational ARPEGE NWP 4-D-Var assimilation system for a period of 3 months. A data-assimilation procedure has been designed and run on 6-h windows. The procedure includes: (1) 4-D-Var assimilating both ozone and operational NWP standard observations, (2) ARPEGE transporting ozone as a passive-tracer, (3) MOCAGE, the Météo-France chemistry and transport model re-initializing the ARPEGE ozone background at the beginning time of the assimilation window. Using observation minus forecast statistics, it is found that the ozone assimilation reduces the wind bias in the lower stratosphere. Moreover, the Degrees of Freedom for Signal diagnostics show that the MLS data covering the 68.1-31.6 hPa vertical pressure range are the most informative and their information content is nearly of the same order as tropospheric humidity-sensitive radiances. Furthermore, with the help of error variance reduction diagnostics, the ozone contribution to the reduction of the horizontal divergence background-error variance is shown to be better than tropospheric humidity-sensitive radiances.

Online coupled regional meteorology chemistry models in Europe: current status and prospects

“…Assimilated aerosol fields may lead to better simulations of the cloudaerosol feedbacks. Semane et al (2009) have shown that the assimilation of stratospheric ozone can have a positive effect on the assimilated wind fields. Finally, it seems plausible that the knowledge of the locations of tracer plumes (e.g.…”

“…First efforts have been made with integrated systems (IFS-MOZART and WRF-Chem) to assimilate chemical and meteorological observations in online integrated models. There is some evidence that CDA can also improve the assimilated meteorological variables, for example the assimilation of ozone can have a positive effect on the assimilated wind fields (Semane et al, 2009). CDA will be beneficial in online coupled model if it improves the realism of the chemical fields which are used to simulate the interaction between atmospheric composition and meteorology.…”

Data assimilation in atmospheric chemistry models: current status and future prospects for coupled chemistry meteorology models

“…In the context of the 4D-Var approach, it would have been possible to use the information content of the atmospheric composition retrievals to correct the dynamic fields as demonstrated by Semane et al (2009). However, earlier experiments (Morcrette, 2003) with IFS did not show a robust benefit for the quality of the meteorological fields.…”

“…The effect of chemical data assimilation on meteorological variables has been investigated in a few specific cases, for example the effect of stratospheric O 3 assimilation on winds (Semane et al, 2009) and that of AOD assimilation on the radiative budget and winds (Jacobson and Kaufman, 2006;Reale et al, 2014). It has also been shown to be potentially important when using a low-order model (Bocquet and Sakov, 2013).…”

“…HCHO satellite data were not assimilated because retrievals were considered insufficient. In this application, the influence of those chemical species on meteorological variables was not taken into account, which is a major difference with the previous application of Semane et al (2009) Several applications using data assimilation have been conducted with WRF-Chem. Scientists at the National Center for Atmospheric Research (NCAR) have assimilated data into WRF-Chem.…”