Naslov
Energy Spectra and Inertia–Gravity Waves in Global Analyses

Autori
Žagar, Nedjeljka ; Damjan Jelić ; Marten Blaauw ; and Peter Bechtold

Izvornik
Journal of the atmospheric sciences (0022-4928) 74 (2017), 8; 2447-2466

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Atmospheric circulation ; Gravity waves ; Inertia-gravity waves ; Data assimilation ; Diagnostics ; Tropical variability

Sažetak
Several decades after E. Dewan predicted that the shallowing of the atmospheric energy spectrum in mesoscale is produced by the inertia–gravity (IG) waves, global analyses have reached the resolution at which the IG waves across many scales are resolved. The authors discuss the spatial filtering method based on the Hough harmonics that provides the temperature and wind perturbations associated with the IG waves in global analysis data. The method is applied to the ECMWF interim reanalysis and the operational 2014–16 analysis fields. The derived spectrum of IG wave energy is divided into three regimes: a part associated with the large-scale unbalanced circulations that has a slope close to −1 for zonal wavenumbers 1 ≤ k ≤ 6, a synoptic-scale range between 3000 and around 500 km (7 ≤ k ≲ 35) that is characterized by a nearly −5/3 slope, and a mesoscale range below 500 km where the slope of the IG energy spectrum in the 2015/16 analyses is steeper. In contrast, the energy spectrum of the Rossby waves has a −3 slope for all zonal wavenumbers k > 6. Presented results suggest that energy associated with the IG modes exceeds the level of energy associated with the Rossby waves around zonal wavenumber 35. The exact wavenumber depends on the season and considered atmospheric depth and it is suggested as a cutoff scale for studies of gravity waves.

Izvorni jezik
Engleski

Znanstvena područja
Geofizika

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