Vertical Coupling

Contact:  Opens window for sending emailHauke Schmidt, Guidi Zhou

 

Atmospheric layers are coupled vertically by radiative, dynamical and chemical processes. We are particularly interested in dynamical coupling between the troposphere, stratosphere and higher layers in both upward and downward directions. For instance, planetary waves originating from the lower atmosphere propagate upward into the stratosphere, where they interact with the polar vortex. In extreme cases, the breaking and dissipation of planetary waves leads to a destruction of the polar vortex, causing the occurrence of a sudden stratospheric warming event. As the strongly disturbed polar vortex feeds back on the tropospheric state, the stratosphere and the troposphere may not be examined separately, but have to be treated as a coupled interacting system. Furthermore, atmospheric gravity waves emanating from the troposphere propagate through the stratosphere and dissipate from up to the mesosphere. The strong gravity wave dissipation near the mesopause is the driving force for the mesospheric general circulation. The interaction between gravity waves and the stratospheric mean flow is also responsible for the QBO, which imposes heavy downward influences on surface weather.

 

The stratosphere is also where external forcing from the outer space (e.g. solar irradiance variations, particle precipitation) directly impacting the upper atmosphere may link down to the Earth’s lower atmosphere.

Topics of stratosphere-troposphere coupling are studied in close collaboration with the "Stratosphere and Climate" (STC) group of Elisa Manzini. Within MUA we have in particular looked at stratospheric impacts of volcanic aerosols, solar variability and anthropogenic forcing (e.g. Bunzel and Schmidt, 2013; Schmidt et al., 2013) and their connection to the troposphere. We are also actively developing the UA-ICON model, a vertical extension of the ICON model into the lower thermosphere, to facilitate the study of gravity waves and their role in vertical coupling between layers of the atmosphere.

Work on vertical coupling within the middle and upper atmosphere has touched upon: vertical coupling through tides (Achatz et al., 2008; Yuan et al., 2008; Kishore Kumar et al., 2013), the mesospheric response to natural and anthropogenic forcing through changes in propagation conditions for waves (Schmidt et al., 2006), the influence of the stratospheric QBO on stratospheric and mesospheric SAO (Pena-Ortiz et al., 2010), downward transport of chemical constituents altered by energetic particle precipitation (Kieser, 2011; Meraner et al., 2016; Meraner and Schmidt, 2016), and vertical coupling of stratosphere and mesosphere during sudden stratospheric warming events (Miller et al., 2013).

 

 

 

Selected Publications

Achatz, U., N. Grieger, and H. Schmidt (2013): Mechanisms Controlling the Diurnal Solar Tide: Analysis Using a GCM and a Linear Model, J. Geophys. Res., 113, A08303, doi:10.1029/2007JA012967.

Bunzel, F., and H. Schmidt (2013): The Brewer-Dobson Circulation in a changing climate: Impact of the model configuration. J. Atmos. Sci., 70, 1437-1455, doi:10.1175/JAS-D-12-0215.1.

Kieser, J. (2011). The influence of precipitating solar and magnetospheric energetic charged particles on the entire atmosphere Simulations with HAMMONIA. PhD Thesis, University of Hamburg, Hamburg.

Kishore Kumar, G., Werner Singer, J. Oberheide, Norbert Grieger, P. P. Batista, D. M. Riggin, H. Schmidt, and B. R. Clemesha (2013): Diurnal tides at low latitudes: Radar, satellite, and model results, J. Atmos. Solar-Terr. Phys., doi:10.1016/j.jastp.2013.07.005.

Meraner, K., Schmidt, H., Manzini, E., Funke, B. & Gardini, A. (2016): Sensitivity of simulated mesospheric transport of nitrogen oxides to parameterized gravity waves . Journal of Geophysical Research-Atmospheres, 121, 12,045-12,061.

Meraner, K. & Schmidt, H. (2016): Transport of Nitrogen Oxides through the winter mesopause in HAMMONIA. Journal of Geophysical Research-Atmospheres, 121, 2556-257, 2016.

Miller, A., H. Schmidt, and F. Bunzel (2013): Vertical coupling of the middle atmosphere during sudden stratospheric warming events. J. Atmos. Sol.-Terr. Phys., 97, 11-21, doi:10.1016/j.jastp.2013.02.008.

Pena-Ortiz, C., H. Schmidt, M. A. Giorgetta, M. Keller (2010): The QBO modulation of the semiannual oscillation in MAECHAM5 and HAMMONIA, J. Geophys. Res., 115, D21106, doi:10.1029/2010JD013898, 2010.

Schmidt, H., S. Rast, F. Bunzel, et al. (2013): Response of the middle atmosphere to anthropogenic and natural forcing in the CMIP5 simulations with the MPI-ESM, J. Adv. Model. Earth Syst., 5, 98-116, doi:10.1002/jame.20014.

Schmidt, H., G. P. Brasseur, M. Charron, E. Manzini, M. A. Giorgetta, T. Diehl, V. I. Fomichev, D. Kinnison, D. Marsh, and S. Walters (2006): The HAMMONIA chemistry climate model: Sensitivity of the mesopause region to the 11-year solar cycle and CO2 doubling. J. Climate, 19, 3903-3931.

Yuan, T., H. Schmidt, C. Y. She, D. A. Krueger, S. Reising (2010): Seasonal variations of semidiurnal tidal perturbations in mesopause region temperature, zonal and meridional winds above Fort Collins, CO (40.6°N, 105°W), J. Geophys. Res., 113, D20103, doi:10.1029/2007JD009687.