Offermann, D., Goussev, O., Kalicinsky, Ch., Koppmann, R., Matthes, Katja , Schmidt, H., Steinbrecht, W. and Wintel, J. (2015) A case study of multi-annual temperature oscillations in the atmosphere: Middle Europe. Journal of Atmospheric and Solar-Terrestrial Physics, 135 . pp. 1-11. DOI 10.1016/j.jastp.2015.10.003.

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Abstract

Highlights:
• Oscillations with 2–5 yr periods are found in atmospheric temperatures from 0–100 km.
• They show very special amplitude and phase profiles.
• They are found to be self-sustained.
• They appear to show period and phase synchronization.

Abstract:
SABER temperature measurements from 2002 to 2012 are analyzed from 18 to 110 km altitude in Middle Europe. Data are complemented by radiosonde measurements in the altitude range from 0 to 30 km. Low frequency oscillations with periods of about 2.4-2.2 yr, 3.4 yr, and 5.5 yr are seen in either data set. Surprising vertical structures in amplitudes and phases are observed with alternating minima and maxima of amplitudes, steep phase changes (180°) at the altitudes of the minima, and constant phase values in between. HAMMONIA CCM simulations driven by boundary conditions for the years 1996 to 2006 are analyzed for corresponding features, and very similar structures are found. Data from another CCM, the CESM-WACCM model, are also analyzed and show comparable results.

Similar oscillation periods have been reported in the literature for the ocean. A possible forcing of the atmospheric oscillations from below was therefore tested with a special HAMMONIA run. Here, climatological boundary conditions were used, i.e. the boundaries in all eleven years were the same. Surprisingly also in this data set the same atmospheric oscillations are obtained. We therefore conclude that the oscillations are intrinsically forced, self-sustained in the atmosphere. The oscillations turned out to be quite robust as they are still found in a HAMMONIA run with strongly reduced vertical resolution. Here only the form of the vertical amplitude and phase profile of the 2.2 yr feature is lost but the oscillation itself is still there, and the two other oscillations are essentially unchanged.

Similar oscillations are seen in the earth surface temperatures. Global Land Ocean Temperature Index data (GLOTI) reaching back to 1880 show such oscillations during all that time. The oscillations are also seen in parameters other than atmospheric temperature. They are found in surface data such as the North Atlantic Oscillation Index (NAO) and in zonal winds in the troposphere and lower stratosphere. The oscillations found are tentatively discussed in terms (of synchronization) of self-sustained non-linear oscillators, as many of their properties resemble such oscillators described in the literature.

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