Meso-scale auroras observed at South Pole Station and McMurdo Station

Multi-wavelength auroral imaging observations have been conducted at the South Pole Station (-74 deg magnetic latitude) and the McMurdo Station (-80 deg magnetic latitude). The South Pole Station is situated at latitudes equatorward, or poleward of the auroral oval, depending on magnetic local time (MLT) and solar wind condition, while the McMurdo station is in the polar cap most of the time. The advantage of the ground-based auroral imaging is to resolve meso-scale structures of the aurora with scale length being less than a few 100s km. The following meso-scale structures of aurora are, for example, identified; (1) Patches of proton aurora ( 100 km) associated with a magnetic impulse event, (2) patches of electron aurora at 557.7 nm ( 100 km) propagating equatorward repetitively in association of Pc3 magnetic pulsation, (3) discrete arcs poleward of shock-induced proton and diffuse auroras, and (4) patches ( 10 km) residing for several hours with its shape being almost preserved. We will also introduce some studies utilizing data from South Pole Station and McMurdo Station, including dayside pulsating patches being correlated well with whistler mode chorus waves and north-south asymmetry of polar patches. These meso-scale auroras provide a key clue for understanding the magnetosphere-ionosphere coupling, in particular, scale-coupling triggering the meso-scale phenomena. We also discuss challenges and future perspectives on the magnetospheric studies utilizing the ground-based observations in Antarctica.