The article presents MODES, a new software for the analysis of properties of balanced and inertio-gravity circulations across many scales in (re)analyses, weather forecasts and climate models. The software and real-time results based on ECMWF model can be found at http://meteo.fmf.uni-lj.si/MODES. Evaluation of models' ability to reproduce the unbalanced tropical circulation is expected to provide new insights on model performance that is helpful to diagnose deficiencies and define improvements.

The paper deals with the comparison of the common periodization methods used to obtain spectral fields of limited-area models for numerical weather prediction. The focus is on the impact the methods have on the spectra of the fields. The results show that detrending and DCT have little impact on the spectra, as does the Boyd method for extension zone. For the ALADIN and HIRLAM methods, the impact depends on the width of the extension zone - the wider the zone, the larger impact on the spectra.