Comparing topside and bottomside-measured characteristics of the F2 layer peak

Nsumei, P.; Reinisch, B. W.; Huang, Xueqin; Bilitza, D.

doi:10.1016/j.asr.2010.06.027

Cited by 11 publications

(7 citation statements)

References 16 publications

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“…Above the F2 peak the topside electron density values predicted by an α ‐Chapman shape of the profile fall off rapidly compared to those obtained by WM sounding (Figures 14a and 14d, dash dot curves). This result is consistent with that of Nsumei et al [2010], who found that the Chapman scale height values for the F2 layer peak derived from topside profiles, H m , top , are generally several times larger than H m , bot derived from bottomside profiles.…”

Section: Comparison Of Radio Sounding Results With In Situ Measuremensupporting

confidence: 92%

Magnetospherically reflected, specularly reflected, and backscattered whistler mode radio-sounder echoes observed on the IMAGE satellite: 2. Sounding of electron density, ion effective mass (meff), ion composition (H+, He+, O+), and density irregularities

2011

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Magnetospherically reflected, specularly reflected, and backscattered whistler mode radio-sounder echoes observed on the IMAGE satellite: 2. Sounding of electron density, ion effective mass (m eff ), ion composition (H + , He + , O + ), and density irregularities along the geomagnetic field line [1] A companion paper by Sonwalkar et al. (2011) provided new details of whistler mode radio sounding of the altitude range below ∼5000 km by the Radio Plasma Imager (RPI) instrument on the IMAGE satellite. That paper presented frequency-vs-group time delay records of echoes whose raypaths either 1) reversed direction through refraction at altitudes above the ionosphere where the wave frequency was approximately equal to the local lower hybrid resonance frequency f lh (magnetospherically reflected or MR echoes), or 2) returned to IMAGE from reflection points along the sharp lower boundary of the ionosphere at ∼90 km (obliquely incident (OI) or normally incident (NI) specularly reflected (SR) echoes). The MR and OI echo paths were shown to form narrow loops, while the NI echo followed the same raypath down and back. Furthermore, the echoes were found to be discrete or broadened in time delay either by multipath propagation or by scattering from field aligned irregularities (FAIs). We begin with a direct interpretive approach, employing a combination of refractive index diagrams, ray tracings, and a plasma density model to predict the detailed frequency-vs-time properties of echoes detected when the sounder is operated over a wide range of whistler mode frequencies (typically 6 kHz to 63 kHz) and the satellite is either above or below the altitude of the maximum f lh along the geomagnetic field line B 0 in the upper ionosphere. We then consider the inverse problem, estimation of the parameters of the prevailing plasma density model from the observed echo properties. Thanks to variations in the sensitivity of the various echo forms to the altitude profiles of electron density and ion effective mass m eff , we use the observed frequency-vs-group time delay (t g − f ) details of simultaneously received MR and SR echoes to infer the properties of a diffusive equilibrium model of the plasma, including estimates of the ion composition in the important transition region from the O + -dominated ionosphere to the light ion regime above. Our results on electron density and ion composition measurements are in general agreement with those obtained from in situ measurements on the IMAGE and DMSP-F15 satellites, with bottomside sounding results from nearby Ionosondes, and with values obtained from the IRI-2007 model. We also demonstrate a method of estimating the scale sizes and locations of FAIs located along or near WM echo paths.Citation: Sonwalkar, V. S., A. Reddy, and D. L. Carpenter (2011), Magnetospherically reflected, specularly reflected, and backscattered whistler mode radio-sounder echoes observed on the IMAGE satellite: 2. Sounding of electron density, ion effective mass (m eff ), ion composition (H + , He + , O + ), and den...

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Section: Comparison Of Radio Sounding Results With In Situ Measuremensupporting

confidence: 92%

Magnetospherically reflected, specularly reflected, and backscattered whistler mode radio-sounder echoes observed on the IMAGE satellite: 2. Sounding of electron density, ion effective mass (meff), ion composition (H+, He+, O+), and density irregularities

2011

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“…The trend in the variation of electron density, that is, decrease in the electron density with increasing L-shell, is consistent with the past measurements by ground ionosondes (Nsumei et al, 2010), International Sun-Earth Explorer (ISEE) data, and those obtained from lightning-generated whistlers (Carpenter & Anderson, 1992). The green cross and black horizontal lines at the F 2 peak altitude in Figures 5a and 5c represent average quiet time n e at the F 2 peak and typical variation of quiet time density at L ∼ 3 and ∼10 MLT around the average value obtained from the past bottomside sounding results (Rishbeth & Mendillo, 2001).…”

Section: Comparison With Past Resultssupporting

confidence: 89%

Evolution of Field‐Aligned Electron and Ion Densities From Whistler Mode Radio Soundings During Quiet to Moderately Active Period and Comparisons With SAMI2 Simulations

2018

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Knowledge of field‐aligned electron and ion distributions is necessary for understanding the physical processes causing variations in field‐aligned electron and ion densities. Using whistler mode sounding by Radio Plasma Imager/Imager for Magnetopause‐to‐Aurora Global Exploration (RPI/IMAGE), we determined the evolution of dayside electron and ion densities along L ∼ 2 and L ∼ 3 (90–4,000 km) during a 7 day (21–27 November 2005) geomagnetically quiet to moderately active period. Over this period the O+/H+ transition height was ∼880 ± 60 km and ∼1000 ± 100 km, respectively, at L ∼ 2 and L ∼ 3. The electron density varied in a complex manner; it was different at L ∼ 2 and L ∼ 3 and below and above the O+/H+ transition height. The measured electron and ion densities are consistent with those from Challenging Minisatellite Payload (CHAMP) and Defense Meteorological Satellite Program (DMSP) and other past measurements, but they deviated from bottomside sounding and International Reference Ionosphere (IRI) 2012 empirical model results. Using SAMI2 (Naval Research Laboratory (NRL) ionosphere model) with reasonably adjusted values of inputs (neutral densities, winds, electric fields, and photoelectron heating), we simulated the evolution of O+/H+ transition height and field‐aligned electron and ion densities so that a fair agreement was obtained between the simulation results and observations. Simulation studies indicated that reduced neutral densities (H and/or O) with time limited O+‐H charge exchange process. This reduction in neutral densities combined with changes in neutral winds and plasma temperature led to the observed variations in the electron and ion densities. The observation/simulation method presented here can be extended to investigate the role of neutral densities and composition, disturbed winds, and prompt penetration electric fields in the storm time ionosphere/plasmasphere dynamics.

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“…During daytime, the H m values range between 20 and 70 km and during nighttime between 30 and 52 km. Nsumei et al (2010) have evaluated the daily variations of the bottomside-derived H m at different latitudes, and have reported a latitude dependence in agreement with our current results. Moreover, the results reported by Zhang et al (2006), Lee and Reinisch (2007), and Nambala et al (2008), using data from Hainan (19.4 • N; 109.0 • E), Jicamarca (12.0…”

Section: Latitudinal Variationsupporting

confidence: 79%

“…Moreover, H m values produced routinely by digisondes can be helpful for constructing the topside electron-density profile when using an appropriate correction factor to estimate the topside scale height (Kutiev et al, 2009). Recent results clearly show that the ratio of H m values deduced from topside and bottomside measurements depend on the local time and latitude (Nsumei et al, 2010). Thus, a better knowledge of the behavior of H m enables a better estimation of vertical profiles to be obtained.…”

Section: Introductionmentioning

confidence: 97%

An analysis of the scale height at the F 2-layer peak over three middle-latitude stations in the European sector

et al. 2012

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This paper presents the results of an analysis of the variations of the scale height at the F 2 -layer peak (H m ) under different seasonal and solar-activity conditions. The database includes hourly H m values derived from ionograms recorded at three middle-latitude stations in the European sector: El Arenosillo (37.1• N; 353.3 • E), Ebro (40.8 • N, 0.5 • E) and Pruhonice (50.0The results show that, in general: (1) H m exhibits diurnal variation with higher values during daytime than during night-time and secondary peaks around sunrise and sunset; (2) during winter time the scale height is lower than in summer time; (3) the scale heights increase with increasing solar activity; (4) H m decreases when the latitude increases; (5) H m shows a low correlation with the F 2 -region peak parameters N m F 2 and h m F 2 and a high correlation with the thickness parameter B 0 and the equivalent slab thickness E ST ; (6) the day-to-day variability is greater at low solar activity than at high solar activity-it reaches maximum values around sunrise or sunset and it is lower around midnight than around noon at low solar activity. The results of this study are similar to those reported by other authors and can be useful for estimating the topside ionosphere from bottomside measurements and modelling.

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Comparing topside and bottomside-measured characteristics of the F2 layer peak

Cited by 11 publications

References 16 publications

Magnetospherically reflected, specularly reflected, and backscattered whistler mode radio-sounder echoes observed on the IMAGE satellite: 2. Sounding of electron density, ion effective mass (meff), ion composition (H+, He+, O+), and density irregularities

Magnetospherically reflected, specularly reflected, and backscattered whistler mode radio-sounder echoes observed on the IMAGE satellite: 2. Sounding of electron density, ion effective mass (meff), ion composition (H+, He+, O+), and density irregularities

Evolution of Field‐Aligned Electron and Ion Densities From Whistler Mode Radio Soundings During Quiet to Moderately Active Period and Comparisons With SAMI2 Simulations

An analysis of the scale height at the F 2-layer peak over three middle-latitude stations in the European sector

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