O. S. Lesyuta

Effects of the August 11, 1999 total solar eclipse as deduced from total electron content measurements at the GPS network

Abstract We present the results derived from measuring fundamental parameters of the ionospheric response to the August 11, 1999 total solar eclipse. Our study is based on using the data from about 100 GPS stations located in the neighborhood of the eclipse totality phase in Europe. The eclipse period was characterized by a low level of geomagnetic disturbance (Dst-variation from −10 to −20 nT ), which alleviated significantly the problem of detecting the ionospheric response to the eclipse. Our analysis revealed a well-defined effect of a decrease (depression) of the total electron content (TEC) for all GPS stations. The delay between minimum TEC values with respect to the totality phase near the eclipse path increased gradually from 4 min in Greenwich longitude (10:40 UT, LT) to 8 min at the longitude 16° (12:09 LT). The depth and duration of the TEC depression were found to be 0.2–0.3 TECU and 60 min , respectively. The results obtained in this study are in good agreement with earlier measurements and theoretical estimates.

Novel technology for detecting atmospheric disturbances using GPS. Instantaneous response of the ionosphere to a sudden commencement of the strong magnetic storms

Abstract We developed a new technology for global detection of atmospheric disturbances, on the basis of phase measurements of the total electron content (TEC) using the international GPS network. Temporal dependencies of TEC are obtained for a set of spaced receivers of the GPS network simultaneously for the entire set of visible satellites. These series are subjected to filtering in the selected range of oscillation periods using known algorithms for spatiotemporal analysis of signals. An “instantaneous” ionospheric response to the sudden commencement of the strong magnetic storms were detected. On the dayside of the Earth the largest value of the net response amplitude was found to be of order 0.4 TECU (2–3 % of the background TEC value), and the delay with respect to the SSC in mid-latitudes was about 360 s. In higher latitudes the delay goes up to 15 min. On the nightside these values are 0.2 TECU and 30 min, respectively. The velocity of the traveling disturbance from the middle to high latitudes on the dayside as well as from the dayside to the nightside was about 10–20 km/s.

Ionospheric effects of the August 11, 1999 total solar eclipse as deduced from European GPS network data

Abstract We present the results derived from measuring fundamental parameters of the ionospheric response to the August 11, 1999 total solar eclipse. Our study is based on using the data from about 70 GPS stations located in the neighbourhood of the eclipse totality phase in Europe. The key feature of our data is a higher reliability of determining the main parameters of the response to eclipse which is due to high space-time resolution and to the increased sensitivity of detection of ionospheric disturbances inherent in the GPS-array method which we are using. Our analysis revealed a well-defined effect of a decrease (depression) of the total electron content (TEC) for all GPS stations. The depth and duration of the TEC depression were found to be 0.2–0.3 TECU and 60 min, respectively. The delay τ between minimum TEC values with respect to the totality phase near the eclipse path increased gradually from 4 min in Greenwich longitude (10:40 UT, LT) to 18 min at the longitude 16° (12:09 LT). The local time-dependence of τ that is revealed in this paper is in agreement with theoretical estimates reported in (Stubbe, 1970).