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Lesyuta, O. S.
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Lesyuta, O. S.
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- PublicationOpen AccessGeomagnetic storms and the occurrence of phase slips in the reception of GPS signals(2002)
; ; ; ; ;Afraimovich, E. L.; Institute of Solar-Terrestrial Physics SD, Russian Academy of Science, Irkutsk, Russia ;Lesyuta, O. S.; Institute of Solar-Terrestrial Physics SD, Russian Academy of Science, Irkutsk, Russia ;Ushakov, I. I.; Institute of Solar-Terrestrial Physics SD, Russian Academy of Science, Irkutsk, Russia ;Voeykov, S. V.; Institute of Solar-Terrestrial Physics SD, Russian Academy of Science, Irkutsk, Russia; ; ; We have investigated a dependence of the relative density of GPS phase slips on the geomagnetic disturbance level. The study is based on using Internet-available selected data from the global GPS network, with the simultaneously handled number of receiving stations ranging from 160 to 323. The analysis used four days from the period 1999-2000, with the values of the geomagnetic field disturbance index Dst from 5 to – 300 nT. During strong magnetic storms, the relative density of phase slips on mid-latitudes exceeds that for magnetically quiet days by one-two orders of magnitude as a minimum, and reaches a few percent of the total density of observations. Furthermore, the level of phase slips for the GPS satellites located on the sunward side of the Earth was by a factor of 5-10 larger compared with the opposite side of the Earth. The level of slips of L 1 phase measurements at the fundamental GPS frequency is at least one order of magnitude lower than that in L 1 – L 2 measurements. The slips of L 1 – L 2 measurements are most likely to be caused by the high level of slips of L 2 phase measurements at the auxiliary frequency. As an alternative, we developed and tested a new method for determining TEC variations using only data on the pseudo-range and phase measurements at fundamental frequency L 1 . The standard deviation of the TEC variations which were obtained in phase measurements at two frequencies, L 1 – L 2 , and at fundamental frequency L 1 , does not exceed 0.1 TECU, which permits this method to be used in strong disturbance conditions when phase slips at auxiliary frequency L 2 are observed.292 511 - PublicationOpen AccessGPS detection of the instantaneous response of the global ionosphere to strong magnetic storms with sudden commencement(2002)
; ; ; ; ; ;Afraimovich, E. L.; Institute of Solar-Terrestrial Physics SD, Russian Academy of Sciences, Irkutsk, Russia ;Kosogorov, E. A.; Institute of Solar-Terrestrial Physics SD, Russian Academy of Sciences, Irkutsk, Russia ;Leonovich, L. A.; Institute of Solar-Terrestrial Physics SD, Russian Academy of Sciences, Irkutsk, Russia ;Lesyuta, O. S.; Institute of Solar-Terrestrial Physics SD, Russian Academy of Sciences, Irkutsk, Russia ;Ushakov, I. I.; Institute of Solar-Terrestrial Physics SD, Russian Academy of Sciences, Irkutsk, Russia; ; ; ; Using a new technology for global GPS detection of ionospheric disturbances, GLOBDET, it has been established that a drastic increase in the time derivative of the magnetic field strength during magnetic storms is accompanied by an almost simultaneous decrease in mid-latitude total electron content on the entire dayside. The corresponding correlation coefficient is not below -0.8; the delay with respect to the time of a magnetic storm sudden commencement is about 3-10 min. This is most pronounced for magnetic storms with a well-marked sudden storm commencement. The sudden storm commencements presented in the paper were observed during the initial storm phase. The analysis reported here was made for a set of from 90 to 300 GPS stations for 10 days in 1998-2001 with a different level of geomagnetic activity (Dst from -6 nT to -295 nT, and K p from 0 to 9). The «simultaneous» total electron content response for the events under consideration was 0.1-0.4 TECU, and the travel velocity of the disturbance from the dayside to the nightside was in the order of 10-20 km/s. Results obtained are consistent with earlier ionospheric parameter measurements obtained using high temporal resolution methods.112 200