Physics of auroral phenomena : proceedings of the 36th Annual seminar, Apatity, 26 February – 01 March, 2013 / [ed. board: A. G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2013. - 215 с. : ил., табл.

/ . / . Shagimuratov et al. 3. Data source The GPS stations with geomagnetic coordinates higher than 55° N and different longitudes were involved to this investigation. The dual-frequency GPS measurements for individual satellite passes used as raw data. Standard GPS observations with 30 sec sampling interval provide information about occurrence of the ionospheric irregularities with size more than 10 km. The GPS measurements of Greenland network were used to study the detail occurrence of TEC fluctuations at the northern high latitude ionosphere. This network provides unique opportunity to monitor TEC variability in polar ionosphere on a regular base. GPS stations are arranged along the latitude over the range 60-83° N (65-87° Corrected Geomagnetic Latitude) near o f 30-40° longitudes. It covers subauroral, auroral and polar ionosphere. As a measure of fluctuation activity the rate of TEC (ROT, in the unit of TECU/min, 1 TECU=1016electron/m2) at 1 min. interval was used [Aarons, 1997]). 4. Temporal occurrence of TEC fluctuations The temporal occurrence of the TEC fluctuations is clearly seen on time variations with the dual frequency carrier phase along satellite passes. As example the TEC variations observed at auroral KELY station for quiet and disturbed conditions presented in Fig. 2. The picture demonstrates the rates of TEC changes along individual satellite pass (PRN15) during quiet (left) and disturbed (right) days. During disturbed conditions the fluctuations of TEC have been essentially increased relative to the quiet condition, the peak values of ROT (0.8 TEC/min) were reached. Universal Time Universal Time Fig. 2 The behavior of TEC fluctuations along individual satellite passes of PRN 15 during quiet and disturbed day. 3 6 9 12 15 18 11.10.2010 KUAQ 3 6 9 12 15 18 9 12 15 18 21 12.10.2010 KUAQ 9 12 15 18 21 6 9 12 15 18 21 10.10.2010 KUAQ 6 9 12 15 18 21 * 4 — -------- * L jHHr: ._______ V - — r - __rzr~~ ---- ---- К .... 6 9 12 15 18 10.10.2010 NNVN 9 12 15 18 21 11.10.2010 NNVN 6 9 12 15 18 12.10.2010 NNVN F ig. 3 Development o f TEC fluctuations at subauroral and auroral stations for quiet and disturbed days. Fig. 3 presents the development of TEC fluctuations for all passes of the satellites observed on subauroral NNVN and auroral KUAQ stations over a 24-hour interval on quiet and disturbed days. For quiet day on subauroral station fluctuations were very low, during geomagnetic disturbed day of 11 October the intensity fluctuations essentially increase after 14 UT. On auroral station during quiet conditions the moderate fluctuations were observed after 20 UT (evening time), at storm day the fluctuations were observed during all day with maximal intensity after 167