Fabry-Perot Interferometer and Skymapping Photometer Determinations of Midlatitude F-Region Neutral Winds and Temperatures and Airglow Enhancement/Depletions.

1984 ◽  
Author(s):  
M. A. Biondi
Keyword(s):  
Neutral Winds ◽  
F Region ◽  
Fabry Perot

scholarly journals Electrodynamics of the Low-latitude Thermosphere by Comparison of Zonal Neutral Winds and Equatorial Plasma Bubble Velocity

2015 ◽  
Vol 20 (2) ◽  
pp. 84-89 ◽  
Author(s):  
Narayan P. Chapagain
Keyword(s):  
Imaging System ◽  
Bubble Velocity ◽  
Plasma Bubble ◽  
Low Latitude ◽  
Neutral Winds ◽  
Coupling Relationship ◽  
F Region ◽  
Fabry Perot ◽  
Optical Imaging System ◽  
Equatorial Plasma Bubble

The coincident observations of nighttime thermospheric zonal neutral winds and equatorial plasma bubble (EPB) drift velocities over Brazil during the October–December,2009 and 2010 are used to examine the coupling relationship between the thermosphere and ionosphere. The EPB zonal drift velocities are estimated using the airglow images recorded by optical imaging system, while the neutral winds are measured by using a bi-static Fabry–Perot interferometer (FPI) experiment deployed at two stations from Brazil. The results reveal the similar pattern in the EPB drift velocities and zonal neutral winds motion during the nighttime and night-to-night thereby illustrating a fully developed F-region dynamo. However, background natural winds also exceed EPBs velocities especially during the development phase of EPBs illustrating that F-region dynamo is not fully activated.Journal of Institute of Science and Technology, 2015, 20(2): 84-89  

Fabry-Perot determinations of midlatitude F-region neutral winds and temperatures from 1975 to 1979

1982 ◽  
Vol 30 (10) ◽  
pp. 1025-1032 ◽  
Author(s):  
Dwight P. Sipler ◽  
Barry B. Luokkala ◽  
Manfred A. Biondi
Keyword(s):  
Neutral Winds ◽  
F Region ◽  
Fabry Perot

The Role of Field-Aligned Current Closure on the E and F-Region Coupled Thermosphere-Ionosphere

2020 ◽  
Author(s):  
Daniel Billett ◽  
Kathryn McWilliams ◽  
Mark Conde
Keyword(s):  
Temporal Structure ◽  
Plasma Velocity ◽  
Velocity Data ◽  
Neutral Winds ◽  
Doppler Imager ◽  
F Region ◽  
Radar Network ◽  
Field Aligned Current ◽  
Auroral Emissions

<p>In this study, the behaviour of both E and F-region neutral winds are examined in the vicinity of intense R1 and R2 field-aligned currents (FACs), measured by AMPERE. This is achieved through the dual sampling of both the green (557.5nm) and red (630nm) auroral emissions, sequentially, from a ground based Scanning Doppler Imager (SDI) located in Alaska.</p><p>With the addition of plasma velocity data from the Super Dual Auroral Radar Network (SuperDARN) and ionospheric parameters from the Poker Flat Incoheerent Scatter Radar (PFISR), we assess how the large closure of Pedersen currents (implied by the strong FACs) modifies the spatial and temporal structure of the neutral wind at different altitudes. We find that the thermosphere becomes significantly height dependent, which could indicate a broader altitude range where the Pedersen conductivity is more important during intense FAC closure.</p>

scholarly journals Thermospheric winds and temperatures above Mawson, Antarctica, observed with an all-sky imaging, Fabry-Perot spectrometer

2009 ◽  
Vol 27 (5) ◽  
pp. 2225-2235 ◽  
Author(s):  
C. Anderson ◽  
M. Conde ◽  
P. Dyson ◽  
T. Davies ◽  
M. J. Kosch
Keyword(s):  
Large Scale ◽  
Atmospheric Model ◽  
Horizontal Wind ◽  
Data Set ◽  
Average Behavior ◽  
Wind Speeds ◽  
Zonal Winds ◽  
F Region ◽  
Fabry Perot ◽  
Thermospheric Winds

Abstract. A new all-sky imaging Fabry-Perot spectrometer has been installed at Mawson station (67°36' S, 62°52' E), Antarctica. This instrument is capable of recording independent spectra from many tens of locations across the sky simultaneously. Useful operation began in March 2007, with spectra recorded on a total of 186 nights. Initial analysis has focused on the large-scale daily and average behavior of winds and temperatures derived from observations of the 630.0 nm airglow line of atomic oxygen, originating from a broad layer centered around 240 km altitude, in the ionospheric F-region. The 1993 Horizontal Wind Model (HWM93), NRLMSISE-00 atmospheric model, and the Coupled Thermosphere/Ionosphere Plasmasphere (CTIP) model were used for comparison. During the geomagnetically quiet period studied, observed winds and temperatures were generally well modelled, although temperatures were consistently higher than NRLMSISE-00 predicted, by up to 100 K. CTIP temperatures better matched our data, particularly later in the night, but predicted zonal winds which were offset from those observed by 70–180 ms−1 westward. During periods of increased activity both winds and temperatures showed much greater variability over time-scales of less than an hour. For the active night presented here, a period of 45 min saw wind speeds decrease by around 180 ms−1, and temperatures increase by approximately 100 K. Active-period winds were poorly modelled by HWM93 and CTIP, although observed median temperatures were in better agreement with NRLMSISE-00 during such periods. Average behavior was found to be generally consistent with previous studies of thermospheric winds above Mawson. The collected data set was representative of quiet geomagnetic and solar conditions. Geographic eastward winds in the afternoon/evening generally continued until around local midnight, when winds turned equatorward. Geographic meridional and zonal winds in the afternoon were approximately 50 ms−1 weaker than expected from HWM93, as was the transition to equatorward flow around midnight. There was also a negligible geographic zonal component to the post-midnight wind where HWM93 predicted strong westward flow. Average temperatures between 19:00 and 04:00 local solar time were around 60 K higher than predicted by NRLMSISE-00.

scholarly journals Lower-thermospheric wind fluctuations measured with an FPI during pulsating aurora at Tromsø, Norway

2010 ◽  
Vol 28 (10) ◽  
pp. 1847-1857 ◽  
Author(s):  
S. Oyama ◽  
K. Shiokawa ◽  
J. Kurihara ◽  
T. T. Tsuda ◽  
S. Nozawa ◽  
...  
Keyword(s):  
Wind Velocity ◽  
Frictional Heating ◽  
Lower Thermosphere ◽  
Thermospheric Wind ◽  
F Region ◽  
Time Period ◽  
Fabry Perot ◽  
Eiscat Radar ◽  
Energy Dissipated ◽  
Uhf Radar

Abstract. Simultaneous observations were conducted with a Fabry-Perot Interferometer (FPI) at a wavelength of 557.7 nm, an all-sky camera at a wavelength of 557.7 nm, and the European Incoherent Scatter (EISCAT) UHF radar during the Dynamics and Energetics of the Lower Thermosphere in Aurora 2 (DELTA-2) campaign in January 2009. This paper concentrated on two events during periods of pulsating aurora. The lower-thermospheric wind velocity measured with the FPI showed obvious fluctuations in both vertical and horizontal components. Of particular interest is that the location of the fluctuations was found in a darker area that appeared within the pulsating aurora. During the same time period, the EISCAT radar observed sporadic enhancements in the F-region backscatter echo power, which suggests the presence of low-energy electron (1 keV or lower) precipitation coinciding with increase in amplitude of the electromagnetic wave (at the order of 10 Hz or higher). While we have not yet identified the dominant mechanism causing the fluctuations in FPI-derived wind velocity during the pulsating aurora, the frictional heating energy dissipated by the electric-field perturbations may be responsible for the increase in ionospheric thermal energy thus modifying the local wind dynamics in the lower thermosphere.

scholarly journals On the usefulness of <i>E</i> region electron temperatures and lower <i>F</i> region ion temperatures for the extraction of thermospheric parameters: a case study

1999 ◽  
Vol 17 (9) ◽  
pp. 1182-1198 ◽  
Author(s):  
J.-P. St.-Maurice ◽  
C. Cussenot ◽  
W. Kofman
Keyword(s):  
Electric Field ◽  
Electron Temperature ◽  
Plasma Temperature ◽  
Ion Temperature ◽  
Heating Rates ◽  
Neutral Winds ◽  
F Region ◽  
E Region ◽  
Effective Electric Field ◽  
Temperature Observations

Abstract. Using EISCAT data, we have studied the behavior of the E region electron temperature and of the lower F region ion temperature during a period that was particularly active geomagnetically. We have found that the E region electron temperatures responded quite predictably to the effective electric field. For this reason, the E region electron temperature correlated well with the lower F region ion temperature. However, there were several instances during the period under study when the magnitude of the E region electron temperature response was much larger than expected from the ion temperature observations at higher altitudes. We discovered that these instances were related to very strong neutral winds in the 110-175 km altitude region. In one instance that was scrutinized in detail using E region ion drift measurement in conjunction with the temperature observations, we uncovered that, as suspected, the wind was moving in a direction closely matching that of the ions, strongly suggesting that ion drag was at work. In this particular instance the wind reached a magnitude of the order of 350 m/s at 115 km and of at least 750 m/s at 160 km altitude. Curiously enough, there was no indication of strong upper F region neutral winds at the time; this might have been because the event was uncovered around noon, at a time when, in the F region, the E×B drift was strongly westward but the pressure gradients strongly northward in the F region. Our study indicates that both the lower F region ion temperatures and the E region electron temperatures can be used to extract useful geophysical parameters such as the neutral density (through a determination of ion-neutral collision frequencies) and Joule heating rates (through the direct connection that we have confirmed exists between temperatures and the effective electric field).Key words. Ionosphere (auroral ionosphere; ionosphere atmosphere interactions; plasma temperature and density)

scholarly journals Ion-neutral coupling in the high-latitude F-layer from incoherent scatter and Fabry-Perot interferometer measurements

2000 ◽  
Vol 18 (9) ◽  
pp. 1145-1153 ◽  
Author(s):  
K. Cierpka ◽  
M. J. Kosch ◽  
M. Rietveld ◽  
K. Schlegel ◽  
T. Hagfors
Keyword(s):  
High Latitude ◽  
Frictional Heating ◽  
Neutral Wind ◽  
Auroral Ionosphere ◽  
Quiet Period ◽  
Ion Temperature ◽  
Incoherent Scatter ◽  
F Region ◽  
Fabry Perot ◽  
Energy Sink

Abstract. Since the auroral ionosphere provides an important energy sink for the magnetosphere, ionosphere-thermosphere coupling must be investigated when considering the energy budget of the ionosphere-magnetosphere coupling. We present the first Scandinavian ground-based study of high-latitude F-region ion-neutral frictional heating where ion velocity and temperature are measured by the EISCAT incoherent scatter radar as well as neutral wind and temperature being measured simultaneously by a Fabry-Perot interferometer. A geomagnetically active period (Kp = 7– – 5–) and quiet period (Kp = 0+ – 0) were studied. Neglecting the neutral wind can result in errors of frictional heating estimates of 60% or more in the F-layer. About 96% of the local ion temperature enhancement over the neutral temperature is accounted for by ion-neutral frictional heating.Key words: Ionosphere (auroral ionosphere; ionosphere-atmosphere interactions)

scholarly journals Deriving the normalised ion-neutral collision frequency from EISCAT observations

1997 ◽  
Vol 15 (12) ◽  
pp. 1557-1569 ◽  
Author(s):  
J. A. Davies ◽  
M. Lester ◽  
T. R. Robinson
Keyword(s):  
Electric Field ◽  
Collision Frequency ◽  
Neutral Atmosphere ◽  
Ion Temperature ◽  
Neutral Winds ◽  
Velocity Magnitude ◽  
F Region ◽  
E Region ◽  
Ion Velocity ◽  
The Difference

Abstract. Common programme observations by the EISCAT UHF radar revealed an extended interval, post geomagnetic local noon on 03 April 1992, during which the F-region ion velocity orthogonal to the geomagnetic field was significantly enhanced, to values exceeding 2 km s–1 corresponding to a perpendicular electric field of some 100 mV m–1. Observations from this interval are used to illustrate a method by which estimates of the E-region ion-neutral collision frequency may be derived in the presence of enhanced electric field. From both the rotation of the ion velocity vector and the reduction in the ion velocity magnitude relative to that in the F-region, independent estimates of the normalised ion-neutral collision frequency are made at the UHF E-region tristatic altitudes; the derived values are, in general, lower than model predictions. Although initial calculations assume a stationary neutral atmosphere, first-order estimates of the E-region neutral wind are subsequently employed to calculate revised estimates of the normalised ion-neutral collision frequency; these neutral winds are derived by attributing the difference between predicted and observed enhancements in field-parallel ion temperature to thermospheric motion. The inclusion of neutral winds, which are themselves not inconsiderable, appears to have only a limited effect on the normalised collision frequencies derived.

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