Middle and Upper Atmosphere

Group Leader: Hauke Schmidt

 

Our aim is to better understand how dynamical and physical processes operate and interact in the region from the upper troposphere to the mesosphere, how they relate to atmospheric composition, and how they couple to surface climate. Of particular interest for us is the susceptibility of the middle atmosphere to external factors, such as solar activity, volcanic and geo-engineered stratospheric aerosols, and greenhouse gases.

For many decades it was assumed that vertical coupling in the atmosphere is efficient only in the upward direction. Today also downward coupling processes are discussed that imply a middle atmosphere influence on tropospheric climate. With respect to this topic we strongly benefit from the close collaboration with the Minerva group of Elisa Manzini on “Stratosphere and Climate” (STC). A new interest in the tropopause region allows us to more closely collaborate with the other groups of the AES department.

In our studies, different numerical models, mostly based on the ICON and ECHAM atmospheric general circulation model are used. Depending on the question these are either the standard version of ECHAM6 reaching up to the mesosphere, eventually integrated in the MPI-Earth System Model MPI-ESM, ECHAM-HAMMOZ (i.e. ECHAM coupled to the Aerosol module HAM and/or the MOZART chemistry module), or the Hamburg Model of the Neutral and Ionized Atmosphere (HAMMONIA). We are currently also developing an upward extension of ICON and are implementing chemistry modules of different complexity into ICON.

 

 

 

Selected recent publications:

 

Bittner, M., Schmidt, H., Timmreck, C. & Sienz, F.: Using a large ensemble of simulations to assess the Northern Hemisphere stratospheric dynamical response to tropical volcanic eruptions and its uncertainty. Geophysical Research Letters, 43, 9324-9332, 2016.

Bittner, M., Timmreck, C., Schmidt, H., Toohey, M. & Krüger , K.: The impact of wave-mean flow interaction on the Northern Hemisphere polar vortex after tropical volcanic eruptions. Journal of Geophysical Research-Atmospheres, 121, 5281-5297, 2016.

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

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

Misios, S. and H. Schmidt: The role of the oceans in shaping the tropospheric response to the 11-year solar cycle, Geophys. Res. Lett, 40, 6373-6377, 2013.

Niemeier, U., H. Schmidt, K. Alterskjær and J. E. Kristjánsson:  Solar irradiance reduction via climate engineering: Impact of different techniques on the energy balance and the hydrological cycle, J. Geophys. Res., 118, 12195–12206, 2013.

Niemeier, U. & Timmreck, C.: What is the limit of climate engineering by stratospheric injection of SO2?. Atmospheric Chemistry and Physics, 15, 9129-9141, 2015.

Schmidt, H., K. Alterskjær, D. Bou Karam, O. Boucher, A. Jones, J. E. Kristjansson, U. Niemeier, … and C. Timmreck: Solar irradiance reduction to counteract radiative forcing from a quadrupling of CO2: climate responses simulated by four earth system models, Earth Syst. Dynam., 3, 63-78, 2012.

Schmidt, H., Rast, S., Bunzel, F., Esch, M., Giorgetta, M. A., Kinne, S., Krismer, T., Stenchikov, G., Timmreck, C., Tomassini, L., & Walz, M.: The response of the middle atmosphere to anthropogenic and natural forcing in the CMIP5 simulations with the MPI-ESM. Journal of Advances in Modeling Earth Systems, 5, 98-116, 2013.

Timmreck, C.: Modeling the climatic effects of volcanic eruptions, Wiley Interdisciplinary Reviews: Climate Change, 3, 545-564, 2012.

Timmreck, C., Pohlmann, H., Illing, S. & Kadow, C.: The impact of stratospheric volcanic aerosol on decadal-scale climate predictions. Geophysical Research Letters, 43, 834-842, 2016.