TY  - THES
AU  - Strube, Cornelia
TI  - Gravity waves resolved in Numerical Weather Prediction products
VL  - 549
PB  - Universität Wuppertal
VL  - Dissertation
CY  - Jülich
M1  - FZJ-2021-02205
SN  - 978-3-95806-567-3
T2  - Schriften des Forschungszentrums Jülich. Reihe Energie & Umwelt / Energy & Environment
SP  - iii, 139 S.
PY  - 2021
N1  - Universität Wuppertal, Diss., 2021
AB  - Gravity waves are important drivers of global circulations in the middle atmosphere. Amongst others they exert drag on the background wind while breaking. Predictive atmospheric simulations are usually based on general circulation models. Those struggle to realistically represent small-scale dynamics like gravity waves, because long time frames and necessary computational efficiency restrict climate model setups to coarse spatial resolutions. Therefore, parametrisations are usually part of forecast model setups of the atmosphere. Parametrisations refer to simplified physical models for subgrid-scale processes including gravity waves. Model studies have shown for instance that missing gravity wave drag influences the global circulation and leads to a systematically late breakdown of the southern-hemispheric polar vortex. In contrast to climate models, weather prediction systems have recently reached operational spatial resolutions that are able to resolve a large part of the gravity wave spectrum in the middle atmosphere. Their products, hence, can be used to investigate the generation and distribution of gravity waves in critical regions like the southern polar vortex region and improve future parametrisation schemes for climate models. This thesis introduces an analysis concept for wave characteristics and the propagation of resolved gravity waves in operational fields from the European Centre for Medium-Range Weather Prediction “Integrated Forecast System” (IFS). The analysis of gravity waves in model data as well as observations is complicated by the abundance of different dynamic processes present in the atmosphere at the same time. Characteristic patterns of inertial instabilities and other wave-like phenomena have been misinterpreted as gravity waves before. Therefore, this thesis focusses first on the ability of different approaches to separate gravity wave signals from the rest of the atmosphere. These methods are referred to as “background removal” and are usually based on the distinction of small- and large-scale phenomena by spectral filtering along different spatial dimensions. The comparison of a vertical and a horizontal filtering approach showed that inertial instability structures are easier separated from gravity waves by applying the horizontal filtering.
LB  - PUB:(DE-HGF)3 ; PUB:(DE-HGF)11
UR  - https://juser.fz-juelich.de/record/892616
ER  -