%0 Journal Article %T Magnetoconjugate phenomena in Alaska and Macquarie Is., Australia in 2003: position of the global maximum iso-aurorae %A L. A. Hajkowicz %J Annales Geophysicae (ANGEO) %D 2006 %I Copernicus Publications %X An extensive magnetometer network in Alaska and Canada (consisting of 6 auroral and sub-auroral stations) and at Macquarie Is. (Australia) was used to study magnetoconjugate phenomena in 2003, using the H-component magnetograms. Altogether 193 magnetically disturbed days (with ¦²Kp¡Ý10) were used in the analysis. The maximum negative swing in the H-component (¦¤H) was assigned for each day from the auroral conjugate station's data. Two types of magnetoconjugate data were found: Type-1 when the daily (00:00¨C24:00 h UT) substorm activity was faithfully reproduced in the H-component variations in the northern and southern auroral zones, and Type-2 when a major peak in disturbance was largely missing in one conjugate location. A distinct maximum in the occurrence of the Type-1 events was in the southern summer (northern winter), reaching almost 70 per cent of cases. A minimum in this type of events was in the southern autumn and winter (around 40%). The correlation between ¦²Kp and ¦¤H for auroral stations faithfully reproduced the percentage occurrence of the Type-1 events for various seasons, with the maximum correlation coefficient r¡Ö0.8 in summer. The time conjugacy of the events (i.e. the events occurring with a small time displacement in the southern and northern auroral zones) was highest for the auroral stations located close to the theoretical conjugate point location at L-value ¡Ö 5 (i.e. College and Macquarie Is.). The substorm onsets started earlier at the stations positioned east of the conjugate point of Macquarie Is. in spring and winter, indicating a westward drift of auroral disturbance with velocities of 1.4¨C1.6 km/s. The magnitude of average ¦¤H increased rapidly past the invariant latitude of Macquarie Is. towards the latitude of its nearest northern conjugate station College , particularly in spring. The average level of disturbance was consistently lower by about 30% at Macquarie Is. than at College. Since Macquarie Is. is the only available auroral station in the southern auroral zone the maximum southern auroral activity level (maximum iso-aurorae) should be inferred from magnetic data obtained at a northern conjugate station positioned at a slightly higher L-value, such as College (L-value = 5.73). It is concluded from the above considerations that the maximum iso-aurorae is located at a shell with L-value ¡Ý 5.73 in both hemispheres. Full Article (PDF, 589 KB) Citation: Hajkowicz, L. A.: Magnetoconjugate phenomena in Alaska and Macquarie Is., Australia in 2003: position of the global maximum iso-aurorae, Ann. Geophys., 24, 2611-2617, doi:10.5194/angeo-24-2611-2006, 2006. Bibtex EndNote Reference Manager XML %U http://www.ann-geophys.net/24/2611/2006/angeo-24-2611-2006.html