Solar rotational effects in the ionosphere and thermosphere

The solar rotational signal has been detected in several ionospheric datasets including topside densities and temperatures, TEC and foF2, as well as incoherent scatter radar. These previous studies have established that the 27-day solar rotational signal is indeed present in the ionosphere and they typically correlate the variation with solar indices such as F10.7 or sunspot number. However, a comprehensive picture of precisely what spectral bands in the XUV are responsible for modifying which parts of the ionosphere still remains lacking. We analyze the solar rotational signal in several data sets including TOPEX/Jason (TEC), DMSP/SSIES (topside ionosphere), DMSP SSUSI (twilight/nighttime ionosphere profile), and COSMIC (global occultation measurements). These differing measurements provide complementary perspectives into the global and altitudinal response of the ionosphere to the solar rotational signal. The TIE-GCM is used mechanistically to examine the solar rotational effect on both the ionosphere and thermosphere. We examine under what conditions the solar rotational signal is significant on the bottom-side ionosphere.