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Abstract Specific polar cap auroras, such as 15MLT‐PCA, linked to lobe reconnection due to the influence of the interplanetary magnetic field (IMF) B_ycomponent, were only observed in the summer. Although the variance in ionospheric conductivity between winter and summer has been proposed as a potential explanation for this seasonal dependency, it has also been argued that the differences in lobe reconnection between the winter and summer hemispheres could be the cause. To address this debate, we examined two data periods with similar IMF conditions when the northern hemisphere was in summer and winter, respectively. Using DMSP/SSUSI and AMPERE observations, we detected clear 15MLT‐PCA and associated field‐aligned currents in the summer, but not in the winter. These observations were compared with global MHD simulations from OpenGGCM. Lobe reconnection signatures were identified for both winter and summer in the simulation results. However, a detailed analysis showed that the pattern of lobe reconnection in the winter hemisphere was different from that in the summer. Based on the combined observation and simulation results, we suggest that particular lobe reconnection in summer is critical for generating 15MLT‐PCA, while the winter's reconnection may lead to transient or small‐scale auroral responses that were not easily identified by DMSP/SSUSI observations as a 15MLT‐PCA event. 

Abstract Throat auroras frequently observed near local noon have been confirmed to correspond to magnetopause indentations, but the generation mechanisms for these indentations and the detailed properties of throat aurora are both not fully understood. Using all‐sky camera and magnetometer observations, we reported some new observational features of throat aurora as follows. (1) Throat auroras can occur under stable solar wind conditions and cause clear geomagnetic responses. (2) These geomagnetic responses can be simultaneously observed at conjugate geomagnetic meridian chains in the Northern and Southern Hemispheres. (3) The initial geomagnetic responses of throat aurora show concurrent onsets that were observed at all stations along the meridians. (4) Immediately after the concurrent onsets, poleward moving signatures and micropositive bays were observed in theXcomponents at higher‐ and lower‐latitude stations, respectively. We argue that these observations provide evidence for throat aurora being generated by low‐latitude magnetopause reconnection. We suggest that the concurrent onsets reflect the instantaneous responses of the reconnection signal arriving at the ionosphere, the followed poleward moving signatures reflect the antisunward dragging of the footprint of newly opened field lines, and the micropositive bays may result from a pair of field‐aligned currents generated during the reconnection. This study may shed new light on the geomagnetic transients observed at cusp latitude near magnetic local noon.