Model description of MIMAS

A 3-d Lagrangian ice transport model called MIMAS is superimposed on LIMA which allows to study the formation and life cycle of ice particles in the polar mesopause region. MIMAS includes modules for a simplified mesospheric chemistry and transport of water vapor, and a Lagrangian transport and microphysical scheme of ice particles (Berger and von Zahn, 2002; von Zahn and Berger). The ice transport model itself requires a nearly continuous initialization (once per hour) of atmospheric 3-d background winds, temperatures, air pressure and densities which are provided by, e.g., LIMA. Furthermore, water vapor data must be provided at the spatial boundaries of the ice model domain (78 to 94 km in altitude, 37.5°N/S to 90°N/S in latitude) to specify boundary conditions of the water vapor transport scheme inside the ice model domain.
The combination of the Lagrangian ice transport model with LIMA background conditions is called MIMAS. In order to calculate ice cloud formation during a full length of a summer season MIMAS starts at May 15th for a northern summer season, and November 15th for a southern summer season. MIMAS initializes the mesopause region with an ensemble of 20 million condensation nuclei (CN). We assume that at the time of model initialization these CN exist in number densities and size distribution similar to the results from Hunten et al. (1980). This distribution is characterized by comprising only particles with radii between 1.5 and 3.5 nm with a large majority of all particles with radii of 1.5-2.0 nm. After initialization we investigate the time-dependent transport of CN in 3-d during a full summer season until August 25th (NH) and February 25th (SH), respectively. MIMAS follows the trajectories of each of the 40 million particles with high temporal resolution (every 3 min) while they are transported by LIMA background winds, particle eddy diffusion, and sedimentation.
Ice layer simulations are shown as animations (16 MByte).

Selected publications

  • U. Berger und F.-J. Lübken, Mesospheric temperature trends at mid-latitudes in summer, Geophys. Res. Lett., L22804, doi:10.1029/2011GL049528, 2011.
  • J. Kiliani, G. Baumgarten, F.-J. Lübken, U. Berger und P. Hoffmann, Temporal and spatial characteristics of the formation of strong noctilucent clouds, J. Atmos. Solar-Terr. Phys., 104, 151-166, doi:10.1016/j.jastp.2013.01.005, 2013.
  • F.-J. Lübken, U. Berger und G. Baumgarten, Stratospheric and solar cycle effects on long-term variability of mesospheric ice clouds, J. Geophys. Res., D00106, doi:10.1029/2009JD012377, 2009.
  • F.-J. Lübken und U. Berger, Latitudinal and interhemispheric variation of stratospheric effects on mesospheric ice layer trends, J. Geophys. Res., 116, D00P03, doi:10.1029/2010JD015258, 2011.
  • F.-J. Lübken, U. Berger, J. Kiliani, G. Baumgarten und J. Fiedler, Solar variability and trend effects in mesospheric ice layers, in Climate And Weather of the Sun-Earth System (CAWSES): Highlights from a priority program, Springer, F.-J. Lübken, Dordrecht, The Netherlands, doi:10.1007/978-94-007-4348-9, 2012.
  • F.-J. Lübken, U. Berger und G. Baumgarten, Temperature trends in the midlatitude summer mesosphere, J. Geophys. Res., 118, 13347-13360, doi:10.1002/2013JD020576, 2013.

Contact

Dr. Uwe Berger

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