Characteristics of F2‐layer planetary wave–type oscillations in northern middle and high latitudes during 2002 to 2008

Kurzfassung

A first description of the characteristics of the F2-layer ionosphere oscillations with periods between 2 and 30 days (so-called planetary wave–type oscillations, PWTO) is derived using regional maps of total electron content (TEC), covering the northern hemisphere from 50°N to the North Pole. Oscillations forced by quasiperiodic variations of solar signals (e.g., extreme ultraviolet irradiation and solar wind) are identified and separated using wavelet transformation. It is found that up to 50% of the PWTO intensity in the F2-layer ionosphere occur due to solar variability. The signals that are not obviously related to solar variability are spectrally decomposed to characterize oscillations by their period and wave number. Climatological analyses of the occurring oscillations in TEC reveal similarities to stratospheric planetary waves (PW). These are typical periods of PW, the strongest wave activity during winter and the enhancement of the wave activity at similar latitudes. But there are also major differences to stratospheric PW. In the ionosphere zonal mean oscillations are dominant, stationary waves are not observed, and the dominant periods are shorter than the typical periods of PW in the stratosphere. However, the obtained results are in good agreement with recent numerical modeling results that showed no stationary wave propagation into the F2-region ionosphere and only fast, short-period waves that propagate up to the lower thermosphere.