The effect of geomagnetic activity on the dynamics of the upper mesosphere-lower thermosphere and on parameters of the Es-layer

Regional response of the mesosphere–lower thermosphere dynamics over Scandinavia to solar proton events and geomagnetic storms in late October 2003

“…Singer et al (1994), using MF and meteor radars, as well as LF wind profilers, also observed a weak reduction of the semidiurnal tide due to geomagnetic storms. In contrast, Pancheva and Mukhtarov (1998) and Fahrutdinova et al (2001) reported an increase in the amplitude of the diurnal and semidiurnal tides. Balan et al (2004) observed different behaviour of the tides in the zonal and meridional wind components.…”

“…Singer et al (1994), using superposed-epoch analysis, demonstrated that there was enhanced westward zonal wind at middle latitudes and an eastward wind at higher latitudes and no reaction in the meridional wind. However, Fahrutdinova et al (2001) reported a reduction in the mean zonal wind and appearance of the northward meridional wind. Nozawa and Brekke (1995), using the EISCAT measurements, found that the differences in the neutral wind patterns between disturbed and quiet days below 109 km are rather small and within the error bars of the experiments, which supported the earlier observations made by Kunitake and Schlegel (1991).…”

Variations in lower thermosphere dynamics at midlatitudes during intense geomagnetic storms

“…As tidal motion is the most prominent feature of mesospheric and lower thermospheric dynamics, different researchers characterized effects of geomagnetic disturbance in terms of changes in tidal components. Fahrutdinova et al [2001] report a reduction in the mean zonal wind and appearance of the northward meridional component, i.e., rotation of the mean wind vector, together with an increase in the amplitude of the diurnal and semidiurnal tides. In contrast, Singer et al [1994] found no reaction in the meridional component and a weak reduction of the semidiurnal tidal amplitude due to geomagnetic storms.…”

“…In spite of these difficulties, the research community has accumulated to date a substantial dataset during geomagnetic storms. Available observations include continuous sets of wind measurements by meteor and medium frequency radars at 80–110 km [e.g., Hook , 1970; Manson and Meek , 1986; Price et al , 1991; Singer et al , 1994; Ma et al , 2001; Fahrutdinova et al , 2001]. At altitudes above ∼110 km, significant evidence of geomagnetic forcing was found in observations made by incoherent scatter radars, especially at high latitudes [e.g., Johnson et al , 1987; Kunitake and Schlegel , 1991; Nozawa and Brekke , 1995; Salah et al , 1996].…”

Dynamical Climatology of the Upper Mesosphere, Lower Thermosphere and Ionosphere

“…Because the wind field is markedly controlled by internal atmospheric processes (e.g., stratospheric warmings, seasonal transitions, atmospheric waves), the individual geomagnetic storm effects are often masked by such atmospheric changes. Fahrutdinova et al (2001) also found a general tendency to westward and northward acceleration associated with geomagnetic storms, when analyzing the long-term meteor radar wind observations in East Europe (Kazan). Although there are some results concerning MLT winds for high latitudes, including the Arctic, Antarctic and even at the South Pole, which show that rapid time variations of the magnetospheric energy cause the wind field to change, we still cannot make statistically significant conclusions for the high-latitude MLT wind climatology.…”