Latitudinal dependence of cosmic noise absorption in the ionosphere over the SAMA region during the September 2008 magnetic storm

摘要

In this work we present and discuss some results of latitudinal dependence in the cosmic noise absorption (CNA) as observed by the South American Riometer Network(SARINET)operated in the South American Magnetic Anomaly(SAMA)region, during a moderate intensity geomagnetic storm that occurred on 3 September 2008. In our analysis, we used the data acquired by the imaging riometers installed at So Martinho da Serra(SSO - geographic coordinate: 29.4°S, 53.1°W), Concepcion(CON - geographic coordinate: 36.5°S, 73.0°W)and Punta Arenas(PAC - geographic coordinate: 53.0°S, 70.5°W)and by the single beam riometer installed at Trelew(TRW - geographic coordinate: 43.1°S, 65.2°W). A comparison among the selected riometer data showed that the mean CNA was more pronounced at SSO, which is the site located nearest to the center of the SAMA, but the second highest value was found at the farther station. Also, a second-order polynomial curve fitting was performed in order to establish an empirical relationship between the mean CNA and the total intensity of the geomagnetic field at the riometer stations.