Workshop: Stratospheric predictability and impact on the troposphere

In order to derive global distributions of gravity waves (GWs) and gravity wave momentum flux (GWMF), temperature observations from various satellite instruments are analyzed for fluctuations. Temperature amplitudes and horizontal and vertical wavelengths are inferred. From these, GWMF is calculated via the polarization relations. This requires different analysis methods for along-track data...

Stratospheric mountain waves will be observed during the planned SOUTHTRAC campagin in southern Argentinia in September/October 2019. First observational highlights from the airborne observations are presented. The selected results will be set in context with analyses of the ECMWF's IFS. Additionally, high-resolution numerical simulations will be presented for the selected cases.

It is common practice in atmospheric models to parameterize gravity waves by pseudo-momentum or Eliassen-Palm flux convergence in the horizontal momentum equation. This approach is justified as long as resolved flow features of interest are in geostrophic and hydrostatic balance (Achatz et al 2017, Wei et al 2018). The present study probes the limits of this ‘pseudomomentum’ approach in a...

Part of gravity wave research is motivated by the need to improve the
representation of their impacts on the large-scale circulation in climate
models. As a major portion of the gravity wave spectrum is subgrid-scale,
parameterizations are responsible for this. Gravity wave parameterizations
generally share a common framework, which includes common assumptions on
their propagation...

The representation of the effects of mesoscale gravity waves (GWs) on the stratospheric circulation is a major source of uncertainty in general circulation models. Due to insufficient understanding of the generating mechanisms of GWs from frontal systems and flow imbalances, these are typically simplified in parameterizations by emitting GWs from a spatially-temporally uniform source at some...