Mathematisch-Naturwissenschaftliche Fakultät

Institut für Physik

Fachgebiet: Atmosphärenphysik

Betreuer: Prof. Dr. Franz-Josef Lübken

Dipl.-Phys. Armin Rudolf Schöch
(e-mail: )

Thermal structure and gravity waves in the Arctic middle atmosphere above ALOMAR (69.3°N, 16°E)

The ALOMAR Rayleigh/Mie/Raman lidar observes the polar middle atmosphere above Northern Norway (69.3°N, 16.0°E). It probes temperatures in the entire middle atmosphere, noctilucent clouds and polar stratospheric clouds since summer 1994. This thesis gives a comprehensive overview of the middle atmosphere temperatures measured with the lidar between 1997 and 2005. During night-time, the lidar temperature measurements cover the altitude range 30km to 85km while in the Arctic summer daylight conditions, temperatures can be derived from 30km to 65km altitude.

The seasonal temperature variation measured with the lidar matches the ECMWF analyses at the lower end of the altitude range and the Luebken1999 rocket climatology in summer at the upper end. Comparisons to other reference atmospheres show larger differences, especially in winter. Part of these can be explained by sudden stratospheric warmings and the generally larger temperature variability in winter. Stratospheric warmings in winter are found to be accompanied by a simultaneous cooling in the middle mesosphere in most cases. Mesospheric inversion layers are observed in 4.6% of all measurements only.

Gravity waves are observed as short-periodic temperature fluctuations in the middle atmosphere. Their energy in the stratosphere is largest in winter and summer and smallest around the equinoxes. The differences in amplitude growth with height indicate stronger wave damping in winter than in summer. The influence of the background wind field on gravity wave propagation is demonstrated in a case-study applying wavelet analyses to a winter measurement. A case-study from the MaCWAVE/MIDAS rocket campaign in summer 2002 shows the large advantage of using joint lidar, radar, falling sphere and radiosonde measurements in studying gravity waves.