We show a possible evidence that the gravity waves(internal gravity waves or acoustic gravity waves) generated by disturbances in the troposphere such as typhoon or rain propagate to the ionospheric E-layer and generate the dynamo currents.

We analyzed magnetic field data obtained by a LEO(Low Earth Orbit) satellite, CHAMP(altitude 300~450 km), and found out the global distribution of the short-period(10~40 s) and small-amplitude(0.1~5 nT) magnetic fluctuations in middle and low latitudes. We have reported that these fluctuations are small-scale structure(~100 km) of the field-aligned currents generated by dynamo action in the ionospheric E-layer and the dynamos are caused by the atmospheric gravity waves (horizontal scale is ~100 km) because of the characteristics of geographical and seasonal dependence of their amplitude.

In this paper, we focused on the mesoscale meteorological events to clarify the atmospheric origin such as typhoon or rain which is possible to generate atmospheric gravity waves, and compare with magnetic fluctuations as observed by the CHAMP satellite above the ionosphere. We trace from the location of CHAMP to each footpoint in the E-layer along geomagnetic field line, and then compared with meteorological phenomena beneath the footpoint.

As a result, we detected large amplitudes of geomagnetic fluctuation above typhoons and meteorological fronts.