Some ionospheric storm effects at an antarctic station

In this paper, the ionospheric response of a high latitude station to some intense geomagnetic storms occurred in 2000 and 2001 is analyzed. For that, data of the critical frequency of the F2-layer foF2 and the virtual height h′F measured at Base Gral. San Martín (68°08′S; 67°06′W) during the storms of April 6, 2000; May 23, 2000; March 31, 2001 and April 11, 2001 (high solar activity) are considered. In order to obtain the features of the disturbances, a comparison of the foF2 data with the outputs of the IRI-2001 model during quiet conditions is made. The results show in general negative storm effects (decreases of foF2 with respect to quiet conditions) following the storm commencement irrespective of the local time. Also, increases in foF2 prior to intense storms are sometimes observed. The h′F data show increases in association with the negative storm effects. The role of some physical mechanisms acting during the phases of the storms is analyzed.