Special issue |
Special Issue on the joint 19th International EISCAT Symposium and 46th Annual European Meeting on Atmospheric Studies by Optical Methods
Editor(s): Juha Vierinen, Noora Partamies, Daniel Whiter, and Andrew J. KavanaghMore information
The EISCAT radars have been providing measurements of the upper atmosphere and ionosphere for over 3 decades; optical measurements (cameras, lidars, photometers, etc.) have provided data for longer than that. In August 2019 the 19th International EISCAT Symposium was held jointly with the 46th Annual European Meeting on Atmospheric Studies by Optical Methods. Following the success of this combined meeting, we are pleased to announce a special issue from this conference. Both the incoherent scatter radar and optical techniques can provide much information on the state of the ionosphere and the larger geospace environment. The joint meeting covered a large number of science areas that can be addressed by EISCAT and/or optical techniques: auroral physics, magnetosphere–ionosphere–thermosphere coupling, space weather impacts, polar cap dynamics; mesopheric dynamics and chemistry, the D-region, airglow, noctilucent clouds and meteors; active experiments and plasma physics; aerosols and clouds, transient luminous events and atmospheric electricity. In addition, there was a session dedicated to novel instruments and methods, including EISCAT 3D and optical instruments. We welcome submissions on all of these topics. We intend this to provide a snapshot of the state of the art in EISCAT and optical research, and as such this call is open to all colleagues working in this area, even if you could not attend the joint meeting. As long as your work is related to EISCAT and/or atmospheric research using optics, you are welcome to make a submission to this special issue.
Fasil Tesema, Noora Partamies, Hilde Nesse Tyssøy, and Derek McKay
Ann. Geophys., 38, 1191–1202, https://doi.org/10.5194/angeo-38-1191-2020,https://doi.org/10.5194/angeo-38-1191-2020, 2020
In this study, we present the ionization level from EISCAT radar experiments and cosmic noise absorption level
from KAIRA riometer observations during pulsating auroras. We found thick layers of ionization that reach down
to 70 km (harder precipitation) and higher cosmic noise absorption during patchy pulsating aurora than
during amorphous pulsating and patchy auroras.
Ann. Geophys., 38, 1101–1113, https://doi.org/10.5194/angeo-38-1101-2020,https://doi.org/10.5194/angeo-38-1101-2020, 2020
We provide an explanation for mysterious radar echoes that look like increases in electron density during incoherent scatter radar measurements made when a high-power high-frequency (4–8 MHz) radio wave is transmitted up into the ionosphere. These echoes are seen at heights from about 200 to 650 km. We suggest that radar echoes at 930 MHz are guided along the earth's magnetic field by electron density irregularities created by the powerful radio wave, similar to light in an optical fibre.
Joshua Dreyer, Noora Partamies, Daniel Whiter, Pål G. Ellingsen, Lisa Baddeley, and Stephan S. Buchert
Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2020-45,https://doi.org/10.5194/angeo-2020-45, 2020
Revised manuscript under review for ANGEO(discussion: final response, 4 comments)
We present observations of a new type of small-scale aurora-like feature, which we name Fragmented Aurora-like Emissions (FAEs). Whereas aurora is caused by particle precipitation, FAEs seem to be locally generated in the ionosphere, hence the term aurora-like.
We analyse data from multiple instruments located near Longyearbyen on Svalbard to derive the main characteristics of FAEs. They seem to occur as two types within a narrow altitude region – individually or in regularly spaced groups.
Pål Gunnar Ellingsen, Dag Lorentzen, David Kenward, Jams H. Hecht, J. Scott Evans, Fred Sigernes, and Marc Lessard
Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2020-50,https://doi.org/10.5194/angeo-2020-50, 2020
Revised manuscript under review for ANGEO(discussion: final response, 5 comments)
Using the RENU2 rocket and ground based instruments, we show that significant parts of the blue aurora above Svalbard at the time of launch was sunlit aurora. Sunlit aurora occurs when nitrogen molecules are ionised by extreme UV sunlight and subsequently hit by electrons from the Sun, resulting in blue/violet emissions. Understanding the source of an auroral emission gives insight into the interaction between the Sun and the Earths upper atmosphere.
Torbjørn Tveito, Juha Vierinen, Björn Gustavsson, and Viswanathan Lakshmi Narayanan
Ann. Geophys. Discuss., https://doi.org/10.5194/angeo-2020-46,https://doi.org/10.5194/angeo-2020-46, 2020
Preprint under review for ANGEO(discussion: final response, 2 comments)
This work explores the role of EISCAT 3D as a tool for planetary mapping. Due to the challenges inherent in detecting the signals reflected from far-away bodies, we have concluded that only the Moon is a viable mapping target. We estimate the impact of the ionosphere on lunar mapping, concluding that it's distorting effects should be easily manageable. EISCAT 3D will be useful for mapping the lunar nearside due to it's previously unused frequency (233 MHz) and it's interferometric capabilities.
Daniel Kastinen, Torbjørn Tveito, Juha Vierinen, and Mikael Granvik
Ann. Geophys., 38, 861–879, https://doi.org/10.5194/angeo-38-861-2020,https://doi.org/10.5194/angeo-38-861-2020, 2020
We have applied three different methods to examine the observability, both tracking and discovery, of near-Earth objects (NEOs) by the EISCAT 3D radar system currently under construction. There are, to our knowledge, no previous studies on the expected discovery rates of NEOs using radar systems. We show that it is feasible to regularly track NEOs and mini-moons. We also show it is possible to discover new NEOs and mini-moons with EISCAT 3D, something never before done with radar systems.
Sam Tuttle, Betty Lanchester, Björn Gustavsson, Daniel Whiter, Nickolay Ivchenko, Robert Fear, and Mark Lester
Ann. Geophys., 38, 845–859, https://doi.org/10.5194/angeo-38-845-2020,https://doi.org/10.5194/angeo-38-845-2020, 2020
Electric fields in the atmosphere near dynamic aurora are important in the physics of the electric circuit within the Earth's magnetic field. Oxygen ions emit light as they move under the influence of these electric fields; the flow of this emission is used to find the electric field at high temporal resolution. The solution needs two other simultaneous measurements of auroral emissions to give key parameters such as the auroral energy. The electric fields increase with brightness of the aurora.