Influence of the ionosphere on the altitude of discrete auroral arcs

Deehr, C. S.; Rees, M. H.; Belon, A. E.; Romick, G. J.; Lummerzheim, D.

doi:10.5194/angeo-23-759-2005

Cited by 7 publications

(9 citation statements)

References 24 publications

(33 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[3] The finding of an increase in the local nighttime auroral intensity from winter to summer is associated with an increase in the energy of precipitating electrons . This is also confirmed, to some extent, by Deehr et al [2005], who found that the average altitude of the maximum luminosity of evening discrete arcs decreases with increasing solar depression angle. Direct measurements of precipitating particles from FAST have also shown an increase (up to ∼50%) in the premidnight sector [Cattell et al, 2006].…”

Section: Introductionsupporting

confidence: 77%

“…At other local times, the mean energy increase is smaller (10–15% for the 09:00–15:00 MLT sector) and is consistent with the FAST results [ Cattell et al , 2006] (∼20% in the 06:00–10:00 MLT sector). Deehr et al [2005] reported that the average energy of the precipitating electrons, inferred by the average peak heights of discrete auroral arcs, in the evening twilight (102°–108° SZA) increases with the solar depression angle. Therefore, one can conclude that the increase in the energy flux of precipitating electrons with a decrease in solar illumination is in large part due to the increase in the average energy of precipitating electrons at all local times.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

TIMED/GUVI observation of solar illumination effect on auroral energy deposition

et al. 2011

View full text Add to dashboard Cite

[1] It has been established that the local nighttime aurora is more intense in winter or darkness than in summer or sunlight. Here we expand previous work to confirm empirical relationships between energy flux and average energy of aurora and solar zenith angle (SZA) and ionospheric photoconductance by analyzing ∼6 years (2002)(2003)(2004)(2005)(2006)(2007) of FUV auroral images acquired from the Global Ultraviolet Imager (GUVI) on board NASA's Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) satellite. The total number of auroral images, north and south combined, is 55,675. The B3C auroral transport code is used to extract auroral parameters, assuming pure electron precipitation. It is found that the mean energy and energy flux carried by precipitating electrons (>0.25 erg/cm 2 s) increase monotonically with SZA for SZA less than ∼108°(corresponding to an EUV shadow height of ∼430 km). The rate of increase is most pronounced in the premidnight sector, where the energy flux rate is ∼0.04 erg/cm 2 s/deg and the mean energy rate is ∼0.02 keV/deg. The auroral power is anticorrelated with the ionospheric Pedersen photoconductance for all local times, with the steepest drop (−0.2 gw/mho) in the midnight sector. These results are stronger than those for the simple cases of "sunlight" versus "darkness" and/or "summer" versus "winter" used in previous work for the solar illumination effect. While the present result cannot distinguish known mechanisms, we suggest that more than one mechanism is responsible for the observed sunlight effect.

show abstract

Section: Introductionsupporting

confidence: 77%

Section: Discussionmentioning

confidence: 99%

TIMED/GUVI observation of solar illumination effect on auroral energy deposition

et al. 2011

View full text Add to dashboard Cite

show abstract

“…Other workers also used this technique, but applied to two photometers only (e.g. Sandholt et al, 1982;Sigernes et al, 1996;Deehr et al, 2005). Sigernes et al (1996) emphasise that their analysis is restricted to narrow auroral structures.…”

Section: Previous Workmentioning

confidence: 99%

A new automatic method for estimating the peak auroral emission height from all-sky camera images

Whiter

Gustavsson

Partamies

et al. 2013

Geosci. Instrum. Method. Data Syst.

View full text Add to dashboard Cite

Abstract. This paper presents a new fully automatic method for quickly finding the average peak emission height of a single auroral structure from a pair of all-sky camera images with overlapping fields of view. The peak emission height of the aurora must be estimated in order to calculate several other important parameters, such as horizontal spatial scales, optical flow velocities, and ionospheric electric fields. In most cases the height is not measured, but a value is assumed, often about 110 km. It is unclear how accurate this assumption is. A future statistical study of the auroral height in which the method presented here will be applied to many years of observations will lead to more accurate assumptions of the height with quantitative error estimates, and therefore more accurate estimates of parameters derived using these assumed auroral heights. In the present work the performance of the new method is compared to another recent automatic method. It is found that the new method measures the peak emission height regardless of the shape of the volume emission rate profile, unlike the other recent method. However, the new method is less suitable than the other method for analysis of very wide auroral arcs (> 30 km) or for aurora in the magnetic zenith of one of the images.

show abstract

“…However, our altitude of interest in the ionosphere was 100 km, as it is the average auroral altitude (Deehr et al, 2005) and we are interested in looking at auroral data for potential optical signatures. Convection vortices, another manifestation of potential signatures, can be observed by the Super Dual Auroral Radar Network (SuperDARN) which looks at reflections in the F region (150 to 800 km) (Greenwald et al, 1995).…”

Section: Perturbation Travel Timementioning

confidence: 99%

Mapping of the quasi-periodic oscillations at the flank magnetopause into the ionosphere

2013

View full text Add to dashboard Cite

Abstract.We have estimated the ionospheric location, area, and travel time of quasi-periodic oscillations originating from the magnetospheric flanks. This was accomplished by utilizing global and local MHD models and Tsyganenko semi-empirical magnetic field model on multiple published and four new cases believed to be caused by the KelvinHelmholtz Instability. Finally, we used auroral, magnetometer, and radar instruments to observe the ionospheric signatures. The ionospheric magnetic latitude determined using global MHD and Tsyganenko models ranged from 58.3-80.2 degrees in the Northern Hemisphere and −59.6 degrees to −83.4 degrees in the Southern Hemisphere. The ionospheric magnetic local time ranged between 5.0-13.8 h in the Northern Hemisphere and 1.3-11.9 h in the Southern Hemisphere. Typical Alfvén wave travel time from spacecraft location to the closest ionosphere ranged between 0.6-3.6 min. The projected ionospheric size calculated at an altitude of 100 km ranged from 47-606 km, the same order of magnitude as previously determined ionospheric signature sizes. Stationary and traveling convection vortices were observed in SuperDARN radar data in both hemispheres. The vortices were between 1000-1800 km in size. Some events were located within the ionospheric footprint ranges. Pc5 magnetic oscillations were observed in SuperMAG magnetometer data in both hemispheres. The oscillations had periods between 4-10 min with amplitudes of 3-25 nT. They were located within the ionospheric footprint ranges. Some ground magnetometer data power spectral density peaked at frequencies within one tenth of a mHz of the peaks found in the corresponding Cluster data. These magnetometer observations were consistent with previously published results.

show abstract

Influence of the ionosphere on the altitude of discrete auroral arcs

Cited by 7 publications

References 24 publications

TIMED/GUVI observation of solar illumination effect on auroral energy deposition

TIMED/GUVI observation of solar illumination effect on auroral energy deposition

A new automatic method for estimating the peak auroral emission height from all-sky camera images

Mapping of the quasi-periodic oscillations at the flank magnetopause into the ionosphere

Contact Info

Product

Resources

About