The global numerical weather prediction models and data assimilation schemes have reached a resolution at which the inertia-gravity (IG) waves are becoming resolved. We present the multivariate decomposition of the global circulation in the balanced and IG components that provides the energy spectrum of the inertia-gravity waves and the quantification of their role in general circulation. The decomposition, provided by the MODES project, is based on the 3D orthogonal normal-mode function representation of the wind and geopotential fields on the terrain-following levels. We compare the results of MODES applied to the three reanalysis: ERA Interim, MERRA and JRA. It is shown that while the global percentage of the wave energy associated with the IG circulation is similar, their spectral characteristics and variability significantly differ among the datasets. In particular, the comparison provides an uncertainty level of the diagnosis of the equatorial Kelvin, the mixed Rossby-gravity and the equatorially trapped IG and balanced modes that are associated with the largest uncertainties in the initial state for the deterministic and ensemble weather forecasting.

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*email: nedjeljka.zagar@fmf.uni-lj.si
*Preference: Oral