First ground‐based OI 630 nm optical measurements of daytime cusplike and F‐region auroral precipitation

Abstract

We have used a high‐resolution (0.012 nm at 630 nm) imaging spectrograph to measure auroral emissions in daytime along the magnetic meridian from Sondrestrom Incoherent Scatter Radar (ISR) facility, at Kangerlussuaq, Greenland (67°N, 51°W; 74.5°N Mag. Lat.). Measured red line (OI 630 nm) brightness during a magnetically disturbed day (January 21, 2001) shows emission enhancements starting at 1330 UT (1130 MLT) and reaching a four‐fold enhancement above the normal dayglow brightness about two hours later. The onset enhancement, characterized by a sharp equatorward boundary, was measured concurrently with ISR Ne and Te, whose morphologies are generally indicative of cusplike precipitation. The 630 nm emission enhancements after 1518 UT correspond to a series of post‐noon F‐region arcs as measured by the ISR. Modeled 630 nm airglow brightness using ISR data, agree well with both the brightness and time history of the daytime optical measurements.