Planetary Wave Type Oscillations (PWTO) Seen in Ionospheric TEC-Maps

Abstract

The coupling of the atmosphere-ionosphere system through planetary waves is a frequently discussed phenomenon. While the climatology of planetary waves in the lower and middle atmosphere is already well known, the impact of these waves to thermospheric/ionospheric processes above 100km still needs deeper investigation. This subject is addressed by analysing hourly maps of Total Electron Content (TEC) of the ionosphere, which are regularly produced by the DLR Neustrelitz. Because the highest electron density exists in the F2-layer, the TEC maps mainly represent the variability of the ionosphere between 200 and 400km altitude. The maps cover the northern hemisphere from 50°N to the polar cap and the years 2002 to 2006. For the analyses the Hayashi algorithm is used providing a separation of waves on one circle of latitude by wavenumber and direction. With the help of this algorithm planetary wave type oscillations in TEC are obtained in the zonal mean and wavenumber one and two. Similar to the behaviour of middle atmosphere planetary waves, TEC disturbances with periods above 10days mainly occur in winter, while shorter periods (below 10days) can be found during the entire year.