Concurrent observations at the magnetic equator of small‐scale irregularities and large‐scale depletions associated with equatorial spread F
Abstract
In 2014 an all‐sky imager (ASI) and an Advanced Modular Incoherent Scatter Radar consisting of 14 panels (AMISR‐14) system were installed at the Jicamarca Radio Observatory. The ASI measures airglow depletions associated with large‐scale equatorial spread F irregularities (10–500 km), while AMISR‐14 detects small‐scale irregularities (0.34 m). This study presents simultaneous observations of equatorial spread F (ESF) irregularities at 50–200 km scale sizes using the all‐sky imager, at 3 m scale sizes using the JULIA (Jicamarca Unattended Long‐term Investigations of the Ionosphere and Atmosphere) radar, and at 0.34 m scales using the AMISR‐14 radar. We compare data from the three instruments on the night of 20–21 August 2014 by locating the radar scattering volume in the optical images. During this night no topside plumes were observed, and we only compare with bottomside ESF. AMISR‐14 had five beams perpendicular to the magnetic field covering ~200 km in the east‐west direction at 250 km altitude. Comparing the radar data with zenith ASI measurements, we found that most of the echoes occur on the western wall of the depletions with fewer echoes observed the eastern wall and center, contrary to previous comparisons of topside plumes that showed most of the echoes in the center of depleted regions. We attribute these differences to the occurrence of irregularities produced at submeter scales by the lower hybrid drift instability. Comparisons of the ASI observations with JULIA images show similar results to those found in the AMISR‐14 and ASI comparison.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Dec 01, 2015
- Source ID
- 10.1002/2015ja021991
Entities
People
- Anja Strømme
- Carlos R. Martinis
- D. A. Hickey
- F. S. Rodrigues
- Juan F. Arratia
- Marco A. Milla
- Michael J. Nicolls
- Roger H Varney
Organizations
- Air Force Office of Scientific Research
- Ana G. Méndez University
- Boston University
- Jicamarca Radio Observatory
- SRI International
- University of Texas at Dallas