Alternating zonal winds in the tropical stratosphere, known as the QBO (quasi-biennial oscillation). A manifestation of the importance of verticle coupling processes in the atmosphere.

Vertical Coupling Processes

Contact: Hauke Schmidt, Elisa Manzini, Felix Bunzel, Andreas Miller

 

The vertical coupling between the different atmospheric layers is characterised by several radiative, dynamical and chemical processes. Most importantly, the stratosphere comprises a number of dynamical features, which depict the impact of the middle atmosphere on the troposphere. On the other hand, stationary waves originating from the surface penetrate the stratosphere in Northern hemispheric winter, where they interact with the polar vortex. In extreme cases, their dissipation can even lead to a destruction of the polar vortex, causing the occurrence of a sudden stratospheric warming event. As the strength of the polar vortex feeds back the tropospheric state, the stratosphere and the troposphere may not be examined separately, but have to be treated as a coupled interacting system.

 

Work on vertical coupling in the MUA group has touched upon the following issues:

  • vertical coupling through tides (Achatz et al., 2008, Yuan et al., 2008)
  • the mesospheric response to natural and anthropogenic forcing through changes in propagation conditions for waves (Schmidt et al., 2006; She et al., 2009)
  • The influence of the stratospheric QBO on stratospheric and mesospheric SAO (Pene-Ortiz et al., 2010)
  • dynamical downward propagation of the solar signal (Schmidt et al., 2010)
  • downward transport of chemical constituents altered by energetic particle precipitation
  • vertical coupling of stratosphere and mesosphere during sudden stratospheric warmings (the relation of tropical waves and the QBO is mainly studied in the Climate Modeling group)
  • dynamical coupling of stratosphere and troposphere

 

In the following we will focus on the latter two issues. Please follow the links below for more information:

 

Impact of stratospheric conditions on the tropospheric state

Origin and propagation of planetary waves

Sudden stratospheric warmings and their mesospheric precursors