scholarly journals Altitude dependence of plasma density in the auroral zone

2002 ◽  
Vol 20 (11) ◽  
pp. 1743-1750 ◽  
Author(s):  
P. Janhunen ◽  
A. Olsson ◽  
H. Laakso
Keyword(s):  
Plasma Density ◽  
Radial Distance ◽  
Auroral Zone ◽  
Auroral Region ◽  
The Earth ◽  
Spacecraft Potential ◽  
Evening Sector ◽  
Altitude Dependence ◽  
Plasma Depletions ◽  
Auroral Phenomena

Abstract. We study the altitude dependence of plasma depletions above the auroral region in the 5000–30 000 km altitude range using five years of Polar spacecraft potential data. We find that besides a general decrease of plasma density with altitude, there frequently exist additional density depletions at 2–4 RE radial distance, where RE is the Earth radius. The position of the depletions tends to move to higher altitude when the ionospheric footpoint is sunlit as compared to darkness. Apart from these cavities at 2–4 RE radial distance, separate cavities above 4 RE occur in the midnight sector for all Kp and also in the morning sector for high Kp. In the evening sector our data remain inconclusive in this respect. This holds for the ILAT range 68–74. These additional depletions may be substorm-related. Our study shows that auroral phenomena modify the plasma density in the auroral region in such a way that a nontrivial and interesting altitude variation results, which reflects the nature of the auroral acceleration processes.Key words. Magnetospheric physics (auroral phenomena; magnetosphere–ionosphere interactions)

scholarly journals INTERBALL-Auroral observations of 0.1-12 keV ion gaps in the diffuse auroral zone

1999 ◽  
Vol 17 (6) ◽  
pp. 734-742 ◽  
Author(s):  
R. A. Kovrazhkin ◽  
J.-A. Sauvaud ◽  
D. C. Delcourt
Keyword(s):  
Plasma Source ◽  
Auroral Zone ◽  
Plasma Convection ◽  
The Earth ◽  
Closed Orbits ◽  
Evening Sector ◽  
Longitudinal Sector ◽  
Particle Orbits ◽  
Auroral Phenomena ◽  
Numerical Orbit

Abstract. We examine ion flux dropouts detected by INTERBALL-Auroral upon traversal of the auroral zone at altitudes of \\sim13 000 up to 20 000 km. These dropouts which we refer to as "gaps", are frequently observed irrespectively of longitudinal sector and appear characteristic of INTERBALL-Auroral ion spectrograms. Whereas some of these gaps display a nearly monoenergetic character (~12 keV), others occur at energies of a few hundreds of eV up to several keV. INTERBALL-Auroral data exhibit the former monoenergetic gap variety essentially in the evening sector. As examined in previous studies, these gaps appear related to transition from particle orbits that are connected with the magnetotail plasma source to closed orbits encircling the Earth. The latter gap variety, which spreads over several hundreds of eV to a few keV is often observed in the dayside magnetosphere. It is argued that such gaps are due to magnetospheric residence times well above the ion lifetime. This interpretation is supported by numerical orbit calculations which reveal extremely large (up to several tens of hours) times of flight in a limited energy range as a result of conflicting E × B and gradient-curvature drifts. The characteristic energies obtained numerically depend upon both longitude and latitude and are quite consistent with those measured in-situ.Key words. Magnetospheric physics (auroral phenomena; plasma convection)

PICASSO: The Golden CubeSat

2021 ◽  
Author(s):  
Noel Baker ◽  
Michel Anciaux ◽  
Philippe Demoulin ◽  
Didier Fussen ◽  
Didier Pieroux ◽  
...  
Keyword(s):  
Electron Temperature ◽  
Plasma Density ◽  
Space Science ◽  
Lessons Learned ◽  
Vertical Profiles ◽  
Proof Of Concept ◽  
Scientific Instruments ◽  
The Earth ◽  
Spacecraft Potential

<p>Led by the Belgian Institute for Space Aeronomy, the ESA-backed mission PICASSO (PICo-Satellite for Atmospheric and Space Science Observations) successfully launched its gold-plated satellite on an Arianespace Vega rocket in September 2020. PICASSO is a 3U CubeSat mission in collaboration with VTT Technical Research Center of Finland Ltd, AAC Clyde Space Ltd. (UK), and the CSL (Centre Spatial de Liège), Belgium. The commissioning of the two onboard scientific instruments is currently ongoing; once they are operational, PICASSO will be capable of providing scientific measurements of the Earth’s atmosphere. VISION, proposed by BISA and developed by VTT, will retrieve vertical profiles of ozone and temperature by observing the Earth's atmospheric limb during orbital Sun occultation; and SLP, developed by BISA, will measure in situ plasma density and electron temperature together with the spacecraft potential.</p><p>Serving as a groundbreaking proof-of-concept, the PICASSO mission has taught valuable lessons about the advantages of CubeSat technology as well as its many complexities and challenges. These lessons learned, along with preliminary measurements from the two instruments, will be presented and discussed.</p>

scholarly journals Statistics of a parallel Poynting vector in the auroral zone as a function of altitude using Polar EFI and MFE data and Astrid-2 EMMA data

2005 ◽  
Vol 23 (5) ◽  
pp. 1797-1806 ◽  
Author(s):  
P. Janhunen ◽  
A. Olsson ◽  
N. A. Tsyganenko ◽  
C. T. Russell ◽  
H. Laakso ◽  
...  
Keyword(s):  
Poynting Vector ◽  
Radial Distance ◽  
Auroral Zone ◽  
Electron Precipitation ◽  
Alfven Wave ◽  
Altitude Range ◽  
Altitude Profile ◽  
Morning Sector ◽  
Field Lines ◽  
Auroral Phenomena

Abstract. We study the wave-related (AC) and static (DC) parallel Poynting vector (Poynting energy flux) as a function of altitude in auroral field lines using Polar EFI and MFE data. The study is statistical and contains 5 years of data in the altitude range 5000–30000 km. We verify the low altitude part of the results by comparison with earlier Astrid-2 EMMA Poynting vector statistics at 1000 km altitude. The EMMA data are also used to statistically compensate the Polar results for the missing zonal electric field component. We compare the Poynting vector with previous statistical DMSP satellite data concerning the electron precipitation power. We find that the AC Poynting vector (Alfvén-wave related Poynting vector) is statistically not sufficient to power auroral electron precipitation, although it may, for Kp>2, power 25–50% of it. The statistical AC Poynting vector also has a stepwise transition at R=4 RE, so that its amplitude increases with increasing altitude. We suggest that this corresponds to Alfvén waves being in Landau resonance with electrons, so that wave-induced electron acceleration takes place at this altitude range, which was earlier named the Alfvén Resonosphere (ARS). The DC Poynting vector is ~3 times larger than electron precipitation and corresponds mainly to ionospheric Joule heating. In the morning sector (02:00–06:00 MLT) we find that the DC Poynting vector has a nontrivial altitude profile such that it decreases by a factor of ~2 when moving upward from 3 to 4 RE radial distance. In other nightside MLT sectors the altitude profile is more uniform. The morning sector nontrivial altitude profile may be due to divergence of the perpendicular Poynting vector field at R=3–4 RE. Keywords. Magnetospheric physics (Auroral phenomena; Magnetosphere-ionosphere interactions) – Space plasma physics (Wave-particle interactions)

scholarly journals Polar observations of electron density distribution in the Earth’s magnetosphere. 2. Density profiles

2002 ◽  
Vol 20 (11) ◽  
pp. 1725-1735 ◽  
Author(s):  
H. Laakso ◽  
R. Pfaff ◽  
P. Janhunen
Keyword(s):  
Electric Field ◽  
Electron Density ◽  
Auroral Zone ◽  
Polar Cap ◽  
Geomagnetic Disturbances ◽  
Activity Data ◽  
Density Peaks ◽  
Spacecraft Potential ◽  
Order Of Magnitude ◽  
Auroral Phenomena

Abstract. Using spacecraft potential measurements of the Polar electric field experiment, we investigate electron density variations of key plasma regions within the magnetosphere, including the polar cap, cusp, trough, plasmapause, and auroral zone. The statistical results were presented in the first part of this study, and the present paper reports detailed structures revealed by individual satellite passes. The high-altitude (> 3 RE) polar cap is generally one of the most tenuous regions in the magnetosphere, but surprisingly, the polar cap boundary does not appear as a steep density decline. At low altitudes (1 RE) in summer, the polar densities are very high, several 100 cm-3 , and interestingly, the density peaks at the central polar cap. On the noonside of the polar cap, the cusp appears as a dense, 1–3° wide region. A typical cusp density above 4 RE distance is between several 10 cm-3 and a few 100 cm-3 . On some occasions the cusp is crossed multiple times in a single pass, simultaneously with the occurrence of IMF excursions, as the cusp can instantly shift its position under varying solar wind conditions, similar to the magnetopause. On the nightside, the auroral zone is not always detected as a simple density cavity. Cavities are observed but their locations, strengths, and sizes vary. Also, the electric field perturbations do not necessarily overlap with the cavities: there are cavities with no field disturbances, as well as electric field disturbances observed with no clear cavitation. In the inner magnetosphere, the density distributions clearly show that the plasmapause and trough densities are well correlated with geomagnetic activity. Data from individual orbits near noon and midnight demonstrate that at the beginning of geomagnetic disturbances, the retreat speed of the plasmapause can be one L-shell per hour, while during quiet intervals the plasmapause can expand anti-earthward at the same speed. For the trough region, it is found that the density tends to be an order of magnitude higher on the day-side (~1 cm-3) than on the nightside (~0.1–1 cm-3), particularly during low Kp.Key words. Magnetospheric physics (auroral phenomena; plasmasphere; polar cap phenomena)

scholarly journals The occurrence frequency of upward ion beams in the auroral zone as a function of altitude using Polar/TIMAS and DE-1/EICS data

2003 ◽  
Vol 21 (10) ◽  
pp. 2059-2072 ◽  
Author(s):  
P. Janhunen ◽  
A. Olsson ◽  
W. K. Peterson
Keyword(s):  
Particle Flux ◽  
Ion Beam ◽  
Radial Distance ◽  
Space Plasma ◽  
Auroral Zone ◽  
Ion Beams ◽  
Occurrence Frequency ◽  
Space Plasma Physics ◽  
Wave Heating ◽  
Auroral Phenomena

Abstract. We study the occurrence frequency of upward auroral ion beams as a function of altitude using three years of  Polar/TIMAS ion data combined with 11 years of DE-1/ EICS ion data, in order to reach a complete altitude coverage between 5000 and 30 000 km. The most interesting result is that there is a peak in ion beam occurrence frequency and invariant energy flux and invariant particle flux at ¢ 3 RE radial distance. The peak exists at about the same altitude in both the evening and midnight MLT sectors. No solar cycle effects are found. We suggest that the peak could be due to a preferred altitude of auroral potential structures at ¢ 3 RE . To substantiate the suggestion, we also present a simple Monte Carlo simulation of ion beams. Another result is that the ion beam occurrence frequency and invariant (mapped to ionospheric altitude) energy and particle fluxes increase in the radial distance range 4–6 RE , suggesting that wave heating processes may take place in this altitude range.Key words. Magnetospheric physics (auroral phenomena; magnetosphere-ionosphere interactions) – Space plasma physics (charged particle motion and acceleration)

Influence of inhomogeneities of the plasma density and electric field on the generation of electrostatic noise in the auroral zone

2015 ◽  
Vol 41 (3) ◽  
pp. 254-261 ◽  
Author(s):  
A. A. Chernyshov ◽  
A. A. Ilyasov ◽  
M. M. Mogilevskii ◽  
I. V. Golovchanskaya ◽  
B. V. Kozelov
Keyword(s):  
Electric Field ◽  
Plasma Density ◽  
Auroral Zone

Wave emission during a plasma density jump in the auroral zone of the topside ionosphere according to the APEX satellite data

2007 ◽  
Vol 47 (6) ◽  
pp. 739-749
Author(s):  
N. I. Izhovkina ◽  
I. S. Prutensky ◽  
S. A. Pulinets ◽  
Z. Klos ◽  
H. Rothkaehl
Keyword(s):  
Plasma Density ◽  
Satellite Data ◽  
Auroral Zone ◽  
Topside Ionosphere ◽  
Density Jump ◽  
Wave Emission

scholarly journals On the altitude dependence of transversely heated O<sup>+</sup> distributions in the cusp/cleft

2004 ◽  
Vol 22 (5) ◽  
pp. 1787-1798 ◽  
Author(s):  
M. Bouhram ◽  
B. Klecker ◽  
W. Miyake ◽  
H. Rème ◽  
J.-A. Sauvaud ◽  
...  
Keyword(s):  
Space Plasma ◽  
Particle Interactions ◽  
Space Plasma Physics ◽  
Ion Outflow ◽  
Oxygen Ion ◽  
Altitude Dependence ◽  
Statistical Studies ◽  
Wave Particle Interactions ◽  
Auroral Phenomena ◽  
First Time

Abstract. The present paper focuses on the altitude dependence of oxygen ion conics in the dayside cusp/cleft region. Here, combining oxygen data from the Akebono, Interball-2 and Cluster satellites allows, for the first time, one to follow the global development of energetic (up to ~10keV) ion outflow over a continuous and broad altitude range up to about 5.5 Earth radii (RE). According to earlier statistical studies, the results are consistent with a height-integrated energization of ions at altitudes up to 3.5 RE. Higher up, the results inferred from Cluster observations put forward evidence of a saturation of both a transverse energization rate and ion gyroradii. We suggest that such results may be interpreted as finite perpendicular wavelength effects (a few tens of km) in the wave-particle interactions. To substantiate the suggestion, we carry out two-dimensional, Monte Carlo simulations of ion conic production that incorporate such effects and limited residence times due to the finite latitudinal extent of the heating region.Key words. Magnetospheric physics (auroral phenomena) – Space plasma physics (charged particle motion and acceleration; wave-particle interactions)

scholarly journals Occurrence of Equatorial Plasma Bubbles during Intense Magnetic Storms

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Chao-Song Huang
Keyword(s):  
Electric Field ◽  
Magnetic Storms ◽  
Ion Density ◽  
Plasma Bubbles ◽  
Defense Meteorological Satellite Program ◽  
Equatorial Plasma Bubbles ◽  
Evening Sector ◽  
Plasma Depletions ◽  
Meteorological Satellite ◽  
The Imf

An important issue in low-latitude ionospheric space weather is how magnetic storms affect the generation of equatorial plasma bubbles. In this study, we present the measurements of the ion density and velocity in the evening equatorial ionosphere by the Defense Meteorological Satellite Program (DMSP) satellites during 22 intense magnetic storms. The DMSP measurements show that deep ion density depletions (plasma bubbles) are generated after the interplanetary magnetic field (IMF) turns southward. The time delay between the IMF southward turning and the first DMSP detection of plasma depletions decreases with the minimum value of the IMFBz, the maximum value of the interplanetary electric field (IEF)Ey, and the magnitude of the Dst index. The results of this study provide strong evidence that penetration electric field associated with southward IMF during the main phase of magnetic storms increases the generation of equatorial plasma bubbles in the evening sector.

Inhomogeneities of plasma density and electric field as sources of electrostatic turbulence in the auroral region

2015 ◽  
Vol 22 (3) ◽  
pp. 032906 ◽  
Author(s):  
Askar A. Ilyasov ◽  
Alexander A. Chernyshov ◽  
Mikhail M. Mogilevsky ◽  
Irina V. Golovchanskaya ◽  
Boris V. Kozelov
Keyword(s):  
Electric Field ◽  
Plasma Density ◽  
Auroral Region
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