Photometric observations of 630.0‐nm OI and 427.8‐nm N2+ emission from South Pole and McMurdo Stations during winter: Analysis of temporal variations spanning minutes to hourly timescales

Abstract

Time series analysis of zenith‐viewing, wide field‐of‐view photometer measurements of thermospheric OI 630.0‐nm and N2+ 427.8‐nm emissions taken simultaneously from South Pole station (90°S geographic) and from McMurdo station (78°S geographic) during the austral winter months of 2003, 2004, and 2005 are presented. The high sampling rate and continuous, extended duration of measurements at both locations allow for the analysis of phenomena with periods spanning the order of minutes to hours. It is shown that high frequency variations (i.e., with periods of order 1 and 10 min) are often observed at both sites which may be, as supported by colocated magnetometer instrumentation, related to periodic injection of plasma associated with magnetospheric pulsations or their generating processes. We also show that oscillations with periods on the order of 1 h are evident in the power spectrum from both South Pole and McMurdo at both altitudes and emissions and are highly variable. The observations of 12‐, 8‐, 6‐, 4.8‐, and 4‐h oscillations are believed to be due to daily sampling of the auroral zone emissions along with potential moonlight contamination. Other observed periods with order 1 h require further study but are likely due to auroral poleward boundary intensifications. The approach presented herein serves as a means to quickly identify time periods of geophysical activity which will be useful in a future analysis of a much greater, extended climatology of the various spectral features, e.g., a 2 decade survey of poleward moving auroral form events currently in progress. The results herein also assist in providing context to the analysis of synoptic space weather events with photometers and provide support for recently reported auroral intensity variations in the Pc5 band.