Planetary wave-type oscillations in the ionosphere and their relationship to mesospheric/lower thermospheric and geomagnetic disturbances at Wuhan (30.6°N, 114.5°E)

Using wind, ionospheric and geomagnetic intensity data observed simultaneously at Wuhan (30.6 degrees N, 114.5 degrees E) in 2002 and 2003, planetary wave type oscillations (PWTO) in the ionosphere and their relationship with oscillations in the mesosphere/lower thermosphere (MLT) and geomagnetic intensity have been investigated. Two cases of 2- and 5-day oscillations in the ionosphere are analyzed to distinguish MLT drivers and geomagnetic drivers. The geomagnetic oscillations are the most important drivers for the PWTO with dominant periods of 5-, 10-, 13.5-day. But the planetary waves in MLT winds are the main drivers for the quasi-2-day oscillations in the ionosphere. The correlation coefficient of the occurrence rates of the 2-day oscillation in winds and in ionospheric f(0)F(2) is 0.82 for the data from February to November. The oscillations in the geomagnetic intensity can drive 30-50% of 5-, 10- and 13.5-day PWTO events in the ionosphere. If we evaluate all of the possible events driven by geomagnetic oscillations, more than 70% of the events have a relationship with geomagnetic oscillations with 5- and 10-day periods. The 39.7 h PWTO in ionospheric plasma frequencies observed from day 161 to 166 in 2002, are generated by an upward propagating wave with period 43.8 h. Two events of 6-day oscillations in the ionosphere observed during May to July in 2003, have different drivers. The first one is probably generated by 5.4-day upward propagating waves in MLT winds, but enhanced during a moderate geomagnetic storm. The second one is generated by the geomagnetic oscillations during a strong geomagnetic storm. (c) 2005 Elsevier Ltd. All rights reserved.