Observations of the E-region horizontal winds in the auroral zone and at mid-latitudes by a ground-based interferometer

1995 ◽  
Vol 13 (11) ◽  
pp. 1172-1186 ◽  
Author(s):  
V. Fauliot ◽  
G. Thuillier ◽  
M. Hersé
Keyword(s):  
Emission Line ◽  
Michelson Interferometer ◽  
Line Emission ◽  
Theoretical Models ◽  
Magnetic Activity ◽  
Auroral Zone ◽  
Empirical Models ◽  
Neutral Wind ◽  
Radar Observations ◽  
E Region

Abstract. The MICADO instrument, consisting of a Michelson interferometer, has observed winds and temperatures during three winter campaigns in the auroral zone, and during 2 years at the Observatoire de Haute-Provence. The instrument observed the O(1S) oxygen emission line. Emission from this line originates from both the E- and F-regions. A method to separate the contribution from these two regions is presented for cases when the thermospheric component is comparable to that for the mesosphere. For the auroral latitudes, a mean model of the meridional and zonal neutral wind components as a function of magnetic activity and time is presented and compared to predictions from recent empirical models. For the mid-latitudes, several properties of the semi-diurnal tides are shown and compared to radar observations and predictions from recent theoretical models.

scholarly journals AIM-E auroral ionosphere model adjustment for the regular E layer

2021 ◽  
Vol 7 (1) ◽  
pp. 41-46
Author(s):  
Vera Nikolaeva ◽  
Evgeniy Gordeev ◽  
Denis Rogov ◽  
Aleksandr Nikolaev
Keyword(s):  
Electron Density ◽  
Input Parameter ◽  
Magnetic Activity ◽  
Auroral Zone ◽  
Auroral Ionosphere ◽  
Solar Radio Flux ◽  
Ionosphere Model ◽  
E Region ◽  
Ap Index ◽  
Euv Spectrum

The E-Region Auroral Ionosphere Model (AIM-E) was developed to determine the chemical composition and electron density in the auroral zone at E-layer heights (90–150 km). Solar and magnetic activity input parameters for AIM-E are the three-hour Ap index and the daily solar radio flux at a wavelength of 10.7 cm (index F10.7). In this paper, we compare AIM-E calculations of the electron density for the daytime with EUV radiation spectrum specified in two different ways: 1) the EUV spectrum theoretically calculated using the F10.7 index as an input parameter; 2) using TIMED satellite direct measurements of the EUV spectrum. We have corrected the EUVAC EUV radiation model to specify a photoionization source in AIM-E. Calculations of regular E-region critical frequencies show good agreement with the vertical sounding data from Russian high-latitude stations. Results we obtained make it possible to do a quick on-line assessment of the regular E layer, using the daily index F10.7 as an input parameter.

scholarly journals AIM-E auroral ionosphere model adjustment for the regular E layer

2021 ◽  
Vol 7 (1) ◽  
pp. 51-58
Author(s):  
Vera Nikolaeva ◽  
Evgeniy Gordeev ◽  
Denis Rogov ◽  
Aleksandr Nikolaev
Keyword(s):  
Electron Density ◽  
Input Parameter ◽  
Magnetic Activity ◽  
Auroral Zone ◽  
Auroral Ionosphere ◽  
Solar Radio Flux ◽  
Ionosphere Model ◽  
E Region ◽  
Ap Index ◽  
Euv Spectrum

The E-Region Auroral Ionosphere Model (AIM-E) was developed to determine the chemical composition and electron density in the auroral zone at E-layer heights (90–150 km). Solar and magnetic activity input parameters for AIM-E are the three-hour Ap index and the daily solar radio flux at a wavelength of 10.7 cm (index F10.7). In this paper, we compare AIM-E calculations of the electron density for the daytime with EUV radiation spectrum specified in two different ways: 1) the EUV spectrum theoretically calculated using the F10.7 index as an input parameter; 2) using TIMED satellite direct measurements of the EUV spectrum. We have corrected the EUVAC EUV radiation model to specify a photoionization source in AIM-E. Calculations of regular E-region critical frequencies show good agreement with the vertical sounding data from Russian high-latitude stations. Results we obtained make it possible to do a quick on-line assessment of the regular E layer, using the daily index F10.7 as an input parameter.

A discussion on D and E region winds over Europe - Winds and temperatures in the auroral zone and their relations to geomagnetic activity

1972 ◽  
Vol 271 (1217) ◽  
pp. 563-575 ◽  
Keyword(s):  
Electric Fields ◽  
Geomagnetic Activity ◽  
Atmospheric Temperature ◽  
Global Scale ◽  
Auroral Zone ◽  
Neutral Wind ◽  
Wind Speeds ◽  
A Value ◽  
Neutral Temperature ◽  
E Region

Measurements of neutral wind velocity and neutral atmospheric temperature above 90 km in the auroral zone have shown distinct correlations with local and global geomagnetic activity respectively. Individual magnetic substorms have been observed to produce neutral wind speeds of over 500 m -s at 130 to 150 km. Ion-neutral particle drag is a likely accelerating mechanism with enhanced meridional electric fields and electron density. These wind disturbances can theoretically propagate to mid-latitudes in the night hemisphere and produce anomalously high neutral wind speeds on a global scale especia y during geomagnetic storm conditions. Such anomalously high wind speeds have been observed on several occasions at mid-latitude sites during disturbed conditions. Neutral temperature values in the auroral zone show a positive correlation with geomagnetic activity with a relatively slow decay following heating. The temperature dependence upon the G9 index (which is representative of jQ) is altitude dependent, increasing from a value near to the global mean (25 K per unit C9) at 140 km to an enhanced value of 50 K per unit G9 at 165 km. Auroral zone measurements are only possible during the period September to April inclusive; however, in this period, during quiet geomagnetic conditions and between 130 and 200 km, there is a decrease of neutral temperature of 150±50K between mid-latitudes (30° N) and the aurora zone (70° N) which is significantly greater than the polewards decrease of temperature predicted from satellite drag density data.

FeXIV Line Emission Polarization of the July 11, 1991 Solar Corona

1994 ◽  
Vol 144 ◽  
pp. 541-547
Author(s):  
J. Sýkora ◽  
J. Rybák ◽  
P. Ambrož
Keyword(s):  
High Resolution ◽  
Solar Corona ◽  
Emission Line ◽  
Solar Eclipse ◽  
White Light ◽  
Preliminary Analysis ◽  
Line Emission ◽  
Total Solar Eclipse ◽  
Degree Of Polarization ◽  
High Resolution Images

AbstractHigh resolution images, obtained during July 11, 1991 total solar eclipse, allowed us to estimate the degree of solar corona polarization in the light of FeXIV 530.3 nm emission line and in the white light, as well. Very preliminary analysis reveals remarkable differences in the degree of polarization for both sets of data, particularly as for level of polarization and its distribution around the Sun’s limb.

scholarly journals Influence of uncertainties of the empirical models for inferring the E-region electric fields at the dip equator

2016 ◽  
Vol 68 (1) ◽  
Author(s):  
Juliano Moro ◽  
Clezio Marcos Denardini ◽  
Laysa Cristina Araújo Resende ◽  
Sony Su Chen ◽  
Nelson Jorge Schuch
Keyword(s):  
Electric Fields ◽  
Empirical Models ◽  
E Region ◽  
Dip Equator

scholarly journals Challenges and Techniques for Simulating Line Emission

Galaxies ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 100 ◽  
Author(s):  
Karen Olsen ◽  
Andrea Pallottini ◽  
Aida Wofford ◽  
Marios Chatzikos ◽  
Mitchell Revalski ◽  
...  
Keyword(s):  
Interstellar Medium ◽  
Emission Line ◽  
Line Emission ◽  
Emission Lines ◽  
Synthetic Spectra ◽  
Recent Advances ◽  
The Future ◽  
Important Quality ◽  
Circumgalactic Medium

Modeling emission lines from the millimeter to the UV and producing synthetic spectra is crucial for a good understanding of observations, yet it is an art filled with hazards. This is the proceedings of “Walking the Line”, a 3-day conference held in 2018 that brought together scientists working on different aspects of emission line simulations, in order to share knowledge and discuss the methodology. Emission lines across the spectrum from the millimeter to the UV were discussed, with most of the focus on the interstellar medium, but also some topics on the circumgalactic medium. The most important quality of a useful model is a good synergy with observations and experiments. Challenges in simulating line emission are identified, some of which are already being worked upon, and others that must be addressed in the future for models to agree with observations. Recent advances in several areas aiming at achieving that synergy are summarized here, from micro-physical to galactic and circum-galactic scale.

scholarly journals The MURALES survey

2020 ◽  
Vol 645 ◽  
pp. A12
Author(s):  
B. Balmaverde ◽  
A. Capetti ◽  
A. Marconi ◽  
G. Venturi ◽  
M. Chiaberge ◽  
...  
Keyword(s):  
Emission Line ◽  
Large Scale ◽  
Line Emission ◽  
Emission Region ◽  
Gas Velocity ◽  
Ionized Gas ◽  
Large Scale Structures ◽  
Scale Structures ◽  
Integral Field Spectrograph ◽  
Integral Field

We present the final observations of a complete sample of 37 radio galaxies from the Third Cambridge Catalogue (3C) with redshift < 0.3 and declination < 20° obtained with the VLT/MUSE optical integral field spectrograph. These data were obtained as part of the MUse RAdio Loud Emission line Snapshot (MURALES) survey with the main goal of exploring the AGN feedback process in the most powerful radio sources. We present the data analysis and, for each source, the resulting emission line images and the 2D gas velocity field. Thanks to the unprecedented depth these observations reveal emission line regions (ELRs) extending several tens of kiloparsec in most objects. The gas velocity shows ordered rotation in 25 galaxies, but in several sources it is highly complex. We find that the 3C sources show a connection between radio morphology and emission line properties. In the ten FR I sources the line emission region is generally compact, only a few kpc in size; only in one case does it exceed the size of the host. Conversely, all but two of the FR II galaxies show large-scale structures of ionized gas. The median extent is 16 kpc with the maximum reaching a size of ∼80 kpc. There are no apparent differences in extent or strength between the ELR properties of the FR II sources of high and low gas excitation. We confirm that the previous optical identification of 3C 258 is incorrect: this radio source is likely associated with a quasi-stellar object at z ∼ 1.54.

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