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%0 Journal Article
%4 sid.inpe.br/iris@1905/2005/08.04.02.15
%2 sid.inpe.br/iris@1905/2005/08.04.02.15.42
%@issn 1364-6826
%F 10474
%T Ionospheric irregularity zonal velocities over Cachoeira Paulista
%D 2002
%8 Aug.-Sep.
%A Paula, Eurico Rodrigues de,
%A Kantor, Ivan Jelinek,
%A Sobral, José Humberto Andrade,
%A Takahashi, Hisao,
%A Santana, Daniela Cristina,
%A Gobbi, Delano,
%A Medeiros, Amauri Fragoso de,
%A Limiro, L. A. T.,
%A Kil, H.,
%A Kintner, P. M.,
%A Taylor, Michael J.,
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%@affiliation Instituto Nacional de Pesquisas Espaciais (INPE)
%@affiliation Johns Hopkins APL, Laurel, MD, USA
%@affiliation Cornell University, Ithaca, NY, USA
%@affiliation Utah State University, Logan, UT, USA
%B Journal of Atmospheric and Solar-Terrestrial Physics
%V 64
%N 12-14
%P 1511-1616
%K aeronomia, global positioning system, equatorial spread-f, radar observations, drifts, scintillation, Brazil, disturbances.
%X We have studied the zonal drift velocity of nighttime ionospheric irregularities from Cachoeira Paulista (22.41°S, 45°W, dip latitude - 17.43°), a station under the Equatorial Anomaly, from December 1998 to February 1999 using LI band GPS receivers and OI 630 nm all-sky images. The average decimetric solar flux index for this period of increasing solar activity was about 145 and magnetically quiet days with SigmaKp < 24 were selected. The GPS technique used receivers spaced 55 in in the magnetic east-west direction and probed small scale plasma structures (scale size about 400 m) at altitudes near 350 kill. The zonal irregularity drift velocities measured by this technique were eastward with values of about 160 m/s at 20 LT, about 140 m/s around midnight, and decreased further in the post-midnight sector. The variability of these drifts decreased significantly after midnight. The zonal velocities of large scale plasma structure were obtained using 01630 nm all-sky images from a region located about 24.1°S and 45°W at a nominal height of 250 kin which corresponds to the bubble projection along the magnetic field lines to 350 km over Cachoeira Paulista. These all-sky imager derived zonal drifts are also eastward, but have magnitudes smaller than the spaced GPS eastward drifts, particularly in the pre-midnight sector. We will discuss these two drift measurement techniques and the interpretation of our results.
%@language en
%3 1-s2.0-S1364682602000883-main.pdf


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