The optical emissions during the HF ionosphere modifications: the ALIS results
Abstract
The Auroral Large Imaging System (ALIS) is a unique scientific facility in 3-D optical imaging of the ionosphere and atmosphere using tomographic inversion tools. Now ALIS consists of six unmanned remote-controlled station located in a grid of ∼ 50 km in northern Sweden. Each station is equipped with sensitive high-resolution unintensified CCD-camera with field-of-view of 60° or 90°. Each camera has a six-position filter-wheel for narrow-band interference filters. Close locations of ALIS and EISCAT Heating facility as well as the low noise and high quantum-efficiency of the ALIS imager make ALIS an ideal instrument for studying optical effect from active ionospheric experiments. Starting in 1995, a series of experiments were carried out, attempting to produce enhanced airglow with the EISCAT Heating facility, and to detect it with ALIS. Since the first images of the 6300Å emission were made on 16 February 1999 a number of successful experiments were conducted. The goal of this report is to present main results obtained with ALIS during these experiments. Most important discoveries are following. (1) For the first time it was obtained the tomographic estimate of the volume distribution of the HF pump enhanced airglow. (2) For the first time the multi wavelength (557.7 nm, 630.0 nm, 427.8 nm, 844.6 nm) measurements of the HF pump--enhanced airglow were conducted. (3) The dependence of the 557.7 nm and the 427.8 nm emissions on HF-frequency was observed during the experiment when the transmitted wave was stepped up and down in frequency through the third harmonic of the ionospheric electron gyro frequency. (4) Precise estimation of the quenching rates of O(1D) state in the upper thermosphere was obtained.
- Publication:
-
35th COSPAR Scientific Assembly
- Pub Date:
- 2004
- Bibcode:
- 2004cosp...35.3141S