The evolution of nighttime mid-latitude mesoscale F-region structures: A case study utilizing numerical solution of the Perkins instability equations

2006 ◽  
Vol 54 (7) ◽  
pp. 710-718 ◽  
Author(s):  
Qina Zhou ◽  
John D. Mathews ◽  
Clark A. Miller ◽  
Ilgin Seker
Keyword(s):  
Numerical Solution ◽  
F Region ◽  
Perkins Instability

Investigation on the role of E-F region coupling processes on the generation of nighttime MSTIDs: Case studies over northern Germany

2021 ◽  
Author(s):  
Mani Sivakandan ◽  
Jorge L Chau ◽  
Carlos Martinis ◽  
Yuichi Otsuka ◽  
Jens Mielich ◽  
...  
Keyword(s):  
Gps Tec ◽  
F Region ◽  
Perkins Instability ◽  
Sporadic E Layers ◽  
Spread F ◽  
E Region ◽  
Sporadic E ◽  
Low Latitude Ionosphere ◽  
Atmospheric Gravity

<p>Northwest to southeast phase fronts with southwestward moving features are commonly observed in the nighttime midlatitude ionosphere during the solstice months at low solar activity. These features are identified as nighttime MSTIDs (medium scale traveling ionospheric disturbances). Initially, they were considered to be a manifestation of neutral atmospheric gravity waves. Later on, investigations showed that the nighttime MSTIDs are electrified in nature and mostly confined to the mid and low latitude ionosphere. Although the overall characteristics of the nighttime MSTIDs are mostly well understood, the causative mechanisms are not well known. Perkins instability mechanism was believed to be the cause of nighttime MSTIDs, however, the growth rate of the instability is too small to explain the perturbations observed. Recently, model simulations and observational studies suggest that coupling between sporadic-E layers and other type of E-region instabilities, and the F region may be relevant to explain the generation of the MSTIDs.</p><p>In the present study simultaneous observation from OI 630 nm all-sky airglow imager, GPS-TEC, ionosonde and Meteor radars, are used to investigate the role of E and F region coupling on the generation of MSTIDs .Nighttime MSTIDs observed on three nights (14 March 2020, 23 March 2020 and 28 May 2020) in the OI 630 nm airglow images over Kuehlungsborn (54°07'N; 11°46'E, 53.79N  mag latitude), Germany, are presented. Simultaneous detrended GPS-TEC measurements also shows presence of MSTIDs on these nights. In addition, simultaneous ionosonde observations over Juliusruh (54°37.7'N 13°22.5'E) show spread-F in the ionograms as well as sporadic-E layer occurrence.  Furthermore, we also investigate the MLT region wind variations during these nights. The role of Es-layers and the interplay between the winds and Es-layers role on the generation of the MSTIDs will be discussed in detail in this presentation.</p><p> </p>

scholarly journals On the origin of mesoscale TIDs at midlatitudes

2011 ◽  
Vol 29 (2) ◽  
pp. 361-366 ◽  
Author(s):  
M. C. Kelley
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Wave Spectrum ◽  
Wave Interaction ◽  
Magnetic Activity ◽  
Auroral Zone ◽  
Ionospheric Disturbances ◽  
F Region ◽  
Perkins Instability ◽  
Classical Gravity

Abstract. A recent breakthrough experiment by Ogawa et al. (2009) showed that Mesoscale Traveling Ionospheric Disturbances (MSTIDs), a common phenomenon at midlatitudes, originate in the auroral zone as gravity waves. Curiously, however, the latter do not seem to be related to magnetic activity. These atmospheric waves are common at high latitudes (Bristow and Greenwald, 1996; Bristow et al., 1996), and we argue here that, as they propagate to lower latitudes, Joule damping reduces the gravity wave spectrum to waves suffering the weakest damping. The direction of weakest damping corresponds to the direction predicted by the Perkins instability (Perkins, 1973) for nighttime MSTIDs. The daytime features reported by Ogawa et al. (2009) are very likely due to classical gravity wave interaction with the F-region ionosphere.

scholarly journals Multi-station investigation of spread F over Europe during low to high solar activity

2018 ◽  
Vol 8 ◽  
pp. A27 ◽  
Author(s):  
Krishnendu Sekhar Paul ◽  
Haris Haralambous ◽  
Christina Oikonomou ◽  
Ashik Paul ◽  
Anna Belehaki ◽  
...  
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Geomagnetic Storms ◽  
Occurrence Rate ◽  
High Solar Activity ◽  
Solar Cycle Variation ◽  
F Region ◽  
Perkins Instability ◽  
Spread F ◽  
Triggering Mechanisms

Spread F is an ionospheric phenomenon which has been reported and analyzed extensively over equatorial regions on the basis of the Rayleigh-Taylor (R-T) instability. It has also been investigated over midlatitude regions, mostly over the Southern Hemisphere with its generation attributed to the Perkins instability mechanism. Over midlatitudes it has also been correlated with geomagnetic storms through the excitation of travelling ionospheric disturbances (TIDs) and subsequent F region uplifts. The present study deals with the occurrence rate of nighttime spread F events and their diurnal, seasonal and solar cycle variation observed over three stations in the European longitude sector namely Nicosia (geographic Lat: 35.29 °N, Long: 33.38 °E geographic: geomagnetic Lat: 29.38 °N), Athens (geographic Lat: 37.98 °N, Long: 23.73 °E geographic: geomagnetic Lat: 34.61 °N) and Pruhonice (geographic Lat: 50.05 °N, Long: 14.41 °E geographic: geomagnetic Lat: 47.7 °N) during 2009, 2015 and 2016 encompassing periods of low, medium and high solar activity, respectively. The latitudinal and longitudinal variation of spread F occurrence was examined by considering different instability triggering mechanisms and precursors which past literature identified as critical to the generation of spread F events. The main findings of this investigation is an inverse solar cycle and annual temporal dependence of the spread F occurrence rate and a different dominant spread F type between low and high European midlatitudes.

scholarly journals Pc3-4 ULF waves observed by the SuperDARN TIGER radar

2005 ◽  
Vol 23 (4) ◽  
pp. 1271-1280 ◽  
Author(s):  
P. V. Ponomarenko ◽  
F. W. F. W. Menk ◽  
C. L. Waters ◽  
M. D. Sciffer
Keyword(s):  
Radar Data ◽  
The North ◽  
F Region ◽  
Magnetometer Data ◽  
High Latitude Ionosphere ◽  
Generation Region ◽  
Field Lines ◽  
Band Limited ◽  
Upstream Solar Wind

Abstract. Despite extensive research, the mechanisms for propagation of Pc3-4 energy from the generation region at the bow shock to the high-latitude ionosphere remain unresolved. We used high temporal (6-12s) and spatial (45km) resolution data from the SuperDARN TIGER radar (Tasmania) to examine Pc3-4 wave signatures at the F-region heights. We focus on a case study on 28 September 2000, when large-amplitude band-limited Pc3-4 oscillations were observed across 10-20 range gates in beam #4 (which points towards the CGM pole) for about four hours preceding MLT noon. These waves were detected in sea-scatter echoes reflected from the ionospheric footprint of the plasmatrough. Nearby ground magnetometer data from Macquarie Island showed very similar variations in both the north-south and east-west components. The radar data revealed the occasional presence of quasi-FLR (field-line resonance) spatial structures with frequencies much higher than those of the local fundamental FLR modes. Detailed spectral analysis of the ionospheric and ground data shows that these structures most probably correspond to a 3rd-harmonic, poloidal-mode FLR. Such observations suggest that compressional Pc3-4 waves produced in the upstream solar wind travel earthward from the magnetopause in the magnetic equatorial plane depositing energy into the Alfvenic modes, as either forced or 3rd-harmonic FLR that reach ionospheric heights along magnetic field lines.

scholarly journals Ionospheric plasma density structures associated with magnetopause motion: a case study using the Cluster spacecraft and the EISCAT Svalbard Radar

2004 ◽  
Vol 22 (7) ◽  
pp. 2369-2379 ◽  
Author(s):  
F. Pitout ◽  
C. P. Escoubet ◽  
E. A. Lucek
Keyword(s):  
Plasma Density ◽  
High Latitude ◽  
Ionospheric Plasma ◽  
Radar Data ◽  
Magnetic Activity ◽  
Electron Population ◽  
F Region ◽  
Moving Plasma ◽  
Ionospheric Plasma Density

Abstract. On 5 January 2003, the footprint of the Cluster spacecraft, then orbiting in the dayside magnetosphere near the magnetopause, was in the close vicinity of the EISCAT Svalbard Radar (ESR) in the dayside afternoon sector. This configuration made possible the study of the magnetopause motion and its direct consequences on the ionospheric plasma at high latitude. Cluster observed multiple magnetopause crossings despite its high latitude, while on the ground the magnetic activity was very low, whereas the ionospheric plasma sounded by the ESR exhibited poleward moving plasma density structures. In this paper, we compare the satellite and radar data, in order to show that the plasma density structures are directly related to the magnetopause motion and its associated pulsed ionospheric flow. We propose that the variations in electric field make the convection velocity vary enough to alter the electron population by accelerating the chemistry in the F-region and act as a source of electron depletion. The magnetopause motion is in this case, a source of plasma density structures in the polar dayside ionosphere.

The Dynamics of Javelin Throw

1975 ◽  
Vol 42 (2) ◽  
pp. 257-262 ◽  
Author(s):  
Tsai-Chen Soong
Keyword(s):  
Differential Equations ◽  
Numerical Solution ◽  
Nonlinear Dynamic ◽  
Center Of Gravity ◽  
West Germany ◽  
Wind Effect ◽  
Pressure Drag ◽  
Technical Details

Wolferman of West Germany won the 1972 World Olympic javelin throw with a throw of 296 ft 10 in. (90.47m). Lusis of the USSR came in second with a throw of 1 in. (2.5cm) less. Had he paid a little more attention to technical details, he could have won. In the present paper, five nonlinear, dynamic differential equations which describe a javelin in flight, the wind effect included, are derived, and a numerical solution is proposed. A case study shows that 3.31m (10.9 ft) could be added to the 1972 record by using a throw angle and initial javelin axis angle of 42 and 35 deg, respectively, instead of the conventional angles of 35 deg. Slightly modifying the contour of the javelin profile, legitimate within current NCAA rules, to move the center of the pressure drag forward to 0.8cm behind its center of gravity, instead of the present 25.7cm, gives an additional gain in range of 16.13m (52.9 ft).

A Case Study on the Numerical Solution and Reduced Order Model of MEMS

2018 ◽  
Vol 19 (1) ◽  
Author(s):  
Hamid Javaheri ◽  
Parisa Ghanati ◽  
Saber Azizi
Keyword(s):  
Numerical Solution ◽  
Reduced Order Model ◽  
Order Model ◽  
Reduced Order
Sign in / Sign up

Export Citation Format

Share Document