Magnetic local time (MLT) dependence of auroral peak emission height and morphology

Abstract. We investigate the bulk behaviour of auroral structures and peak emission height as a function magnetic local time (MLT). These data are collected from Fennoscandian Lapland Svalbard latitudes seven identical all-sky cameras (ASC) over about one solar cycle. The analysis focusses on green emission, which is where morphology most clearly visible number images highest. typical blue aurora varies 110 km nightside to 118 in morning MLT region. It stays systematically higher (at 118–120 km) at high (Svalbard) during nighttime reaches 140 around noon. During wind speed (above 500 s?1), heights appear 5 lower than slow (below 400 s?1). sign interplanetary field (IMF) has nearly no effect night sector, but northward IMF causes dawn noon hours Svalbard. While former interpreted change particle population within field-of-view (FoV), latter rather due movement cusp location orientation. sector also show pronounced difference when previously detected pulsating (PsA) events have been excluded/included dataset, suggesting that this type dominant phenomenon an important dissipation mechanism. An increase complex midnight agrees with average substorm occurrence. This amplified stronger driving geomagnetic activity (as measured by electrojet index, AL). speed, latitude evolution shows particularly morphology, not limited only excludes hours. further enhances structural complexity sector.