Observations of the HF induced total electron content variations along the paths of the gps signals above the sura facility
Abstract
Recently several authors reported experimental evidences total electron content (TEC) varia-tions along the paths of GPS satellite signals caused by the HF heating of the F2 region of the ionosphere [1,2]. Here we present results on TEC variations caused by the vertical pumping of the ionosphere by radiation of the SURA facility at a frequency 4.3 MHz. In our experiments we used differ-ent pump radiation schedules, like [30 s "on", 30 s "off"]; [2 minutes "on" 2 minutes "off"]; [2 min "on" 4 minutes "off"]; and continuous pumping. The most reliable evidence of the pump-induced TEC variations was obtained on August 27, 2009. During the experiment the continuous pumping of the ionosphere with effective radiated power 60 MW started approxi-mately 5 minutes prior to Ionospheric Penetration Point (IPP) for GPS G21 signal entrance to the heated volume of the ionosphere (at (-3) dB level of the heater beam). The TEC variations were observed during whole IPP pass across the heated volume (from 17:45 to 18:22 UT, LT DST=UT+4 hours) despite of the switch of the pumping schedule from continuous one to [2 minutes "on", 4 minutes "off"] after the IPP passed the culmination point (18:05 UT, 6° to the South from zenith above the SURA facility). The TEC variations achieved a value 0.3 TECU (1 TEC Unit = 1.0 · 1016 el/m2 ), which was approximately 0.7% of the average measured TEC. Estimations performed with the use of ionograms, IRI 2007 model and existing knowledge of the large scale pump induced irregularities in the F2 region of the ionosphere have shown that the TEC variations observed can be attributed to the irregularities with the scales ∼ 5-15 km along the IPP track (i.e. across the pump beam) and 100 km along the geomagnetic field. The work is supported by RFBR grants 10-02-00642, 09-02-01150 and Federal Special-purpose Program "Scientific and pedagogical personnel of innovative Russia". [1] G. Milikh, A.Gurevich, K. Zybin, J. Secan, Geophys. Res. Lett., 2008, 35, L22102, doi:10.1029/2008GL035527. [2] E.D. Tereshchenko, A.N. Milichenko, V.L. Frolov, R.Yu. Yurik., Radiophys and Quantum Electron, 2008, 51, 842-846.
- Publication:
-
38th COSPAR Scientific Assembly
- Pub Date:
- 2010
- Bibcode:
- 2010cosp...38.1561G