Abstract
Abstract. Simultaneous observations were made of dynamic aurora during substorm activity on 26 January 2006 with three high spatial and temporal resolution instruments: the ASK (Auroral Structure and Kinetics) instrument, SIF (Spectrographic Imaging Facility) and ESR (EISCAT Svalbard Radar), all located on Svalbard (78° N, 16.2° E). One of the narrow field of view ASK cameras is designed to detect O+ ion emission at 731.9 nm. From the spectrographic data we have been able to determine the amount of contaminating N2 and OH emission detected in the same filter. This is of great importance to further studies using the ASK instrument, when the O+ ion emission will be used to detect flows and afterglows in active aurora. The ratio of O+ to N2 emission is dependent on the energy spectra of electron precipitation, and was found to be related to changes in the morphology of the small-scale aurora. The ESR measured height profiles of electron densities, which allowed estimates to be made of the energy spectrum of the precipitation during the events studied with optical data from ASK and SIF. It was found that the higher energy precipitation corresponded to discrete and dynamic features, including curls, and low energy precipitation corresponded to auroral signatures that were dominated by rays. The evolution of these changes on time scales of seconds is of importance to theories of auroral acceleration mechanisms.
Highlights
Ground-based observations of active aurora have shown the prevalence of dynamic fine structure within auroral displays, often with sub-second time scales and sub-km filamentation.Recent instrumental development within this field has led to an increase in detailed studies concerning thin auroral arcs and filaments (Lanchester et al, 1997; Trondsen and Cogger, 1998; Semeter and Blixt, 2006)
Simultaneous observations were made of dynamic aurora during substorm activity on 26 January 2006 with three high spatial and temporal resolution instruments: the ASK (Auroral Structure and Kinetics) instrument, SIF (Spectrographic Imaging Facility) and ESR (EISCAT Svalbard Radar), all located on Svalbard (78◦ N, 16.2◦ E)
It is found that emissions in ASK2 and the sum of N2 and O+ emissions in SIF panel O+(7319) follow each other closely (Fig. 3, top panel)
Summary
Ground-based observations of active aurora have shown the prevalence of dynamic fine structure within auroral displays, often with sub-second time scales and sub-km filamentation. Multispectral imaging is an important tool for understanding the processes that are responsible for the dynamics and spatial variations of auroral structures (Semeter et al, 2001) Another type of instrument used for measuring auroral signatures is the imaging spectrograph, which may provide simultaneous measurements in the wavelength region of the imager filters. The 2-D images obtained with ASK provide detailed auroral morphology which is used in addition to the ESR electron density profiles to give a full description of the studied events. These profiles contain information about the energy distribution of the precipitating electrons. SIF is placed at the Auroral Station in Adventdalen, located 7 km north-west of the ESR site
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