scholarly journals Using scale heights derived from bottomside ionograms for modelling the IRI topside profile

2005 ◽  
Vol 2 ◽  
pp. 293-297 ◽  
Author(s):  
B. W. Reinisch ◽  
X. Huang ◽  
A. Belehaki ◽  
R. Ilma
Keyword(s):  
Signal Analysis ◽  
Electron Density Profile ◽  
Electron Content ◽  
Satellite Measurements ◽  
Total Electron ◽  
Incoherent Scatter ◽  
Low Altitude ◽  
Satellite Beacon ◽  
Layer Peak ◽  
Good Agreement

Abstract. Groundbased ionograms measure the Chapman scale height HT at the F2-layer peak that is used to construct the topside profile. After a brief review of the topside model extrapolation technique, comparisons are presented between the modeled profiles with incoherent scatter radar and satellite measurements for the mid latitude and equatorial ionosphere. The total electron content TEC, derived from measurements on satellite beacon signals, is compared with the height-integrated profiles ITEC from the ionograms. Good agreement is found with the ISR profiles and with results using the low altitude TOPEX satellite. The TEC values derived from GPS signal analysis are systematically larger than ITEC. It is suggested to use HT , routinely measured by a large number of Digisondes around the globe, for the construction of the IRI topside electron density profile.

scholarly journals Electron density profile modeling

1996 ◽  
Vol 39 (3) ◽  
Author(s):  
R. G. Ezquer ◽  
M. Mosert de Gonzalez ◽  
T. Heredia
Keyword(s):  
Electron Density ◽  
Characteristic Point ◽  
Base Point ◽  
Electron Density Profile ◽  
Electron Content ◽  
Total Electron ◽  
F Region ◽  
Bottom Side ◽  
The Difference ◽  
Good Agreement

The Base Point Model (BPM) is used to model the electron density (N) profile in the ionosphere, This model assumes two Chapman profile expressions one for the bottomside and one for the topside, and requires a characteristic point called "F region base point". The comparison among the modeled and experimental bottom-side N profiles obtained from Tucuman (26,9°S; 65.4°W) ionosonde shows that, in general, there is a very good agreement within 30 km below the height of the maximum N(hm). Cases with a very good agreement for the entire N-profile are observed. The study of the electron content below hm and the Total Electron Content (TEC) measured over Tucuman shows that, the difference among predicted and measured TEC is due to the disagreement in the topside N-profile more than that observed in the bottomside N-profile.

scholarly journals Topside ionospheric vertical electron density profile reconstruction using GPS and ionosonde data: possibilities for South Africa

2011 ◽  
Vol 29 (2) ◽  
pp. 229-236 ◽  
Author(s):  
P. Sibanda ◽  
L. A. McKinnell
Keyword(s):  
South Africa ◽  
Electron Density ◽  
Geographic Location ◽  
Electron Density Profile ◽  
Empirical Modeling ◽  
Topside Ionosphere ◽  
Electron Content ◽  
Total Electron ◽  
Gps Tec ◽  
Profile Reconstruction

Abstract. Successful empirical modeling of the topside ionosphere relies on the availability of good quality measured data. The Alouette, ISIS and Intercosmos-19 satellite missions provided large amounts of topside sounder data, but with limited coverage of relevant geophysical conditions (e.g., geographic location, diurnal, seasonal and solar activity) by each individual mission. Recently, methods for inferring the electron density distribution in the topside ionosphere from Global Positioning System (GPS)-based total electron content (TEC) measurements have been developed. This study is focused on the modeling efforts in South Africa and presents the implementation of a technique for reconstructing the topside ionospheric electron density (Ne) using a combination of GPS-TEC and ionosonde measurements and empirically obtained Upper Transition Height (UTH). The technique produces reasonable profiles as determined by the global models already in operation. With the added advantage that the constructed profiles are tied to reliable measured GPS-TEC and the empirically determined upper transition height, the technique offers a higher level of confidence in the resulting Ne profiles.

GPS satellite measurements: ionospheric slab thickness and total electron content

1995 ◽  
Vol 57 (14) ◽  
pp. 1723-1732 ◽  
Author(s):  
G.L. Goodwin ◽  
J.H. Silby ◽  
K.J.W. Lynn ◽  
A.M. Breed ◽  
E.A. Essex
Keyword(s):  
Total Electron Content ◽  
Slab Thickness ◽  
Electron Content ◽  
Satellite Measurements ◽  
Total Electron

scholarly journals Analysis of Ionospheric and Geomagnetic Response to the 2020 Patagonian Solar Eclipse

2021 ◽  
Vol 8 ◽  
Author(s):  
Amalia Meza ◽  
Bernardo Eylenstein ◽  
María Paula Natali ◽  
Guillermo Bosch ◽  
Juan Moirano ◽  
...  
Keyword(s):  
Geomagnetic Field ◽  
Lower Ionosphere ◽  
Electron Content ◽  
Vertical Total Electron Content ◽  
Total Electron ◽  
Average Speed ◽  
Rio Negro ◽  
Set Up ◽  
The City ◽  
Good Agreement

Total solar eclipses are unique opportunities to study how the ionospheric and external geomagnetic field responds to fast changes in the ionizing flux as the moon’s shadow travels through its path over the ionosphere at an average speed of 3,000 km/h. In this contribution, we describe our observing campaign in which we set up GNSS and geomagnetic stations at the city of Valcheta, Río Negro, Argentina (which was located right under the path of totality). We also describe the results obtained from the analysis of the combination of on-site data together with publicly available observations from geodetic and geomagnetic observatories. The large span in latitude of our data allowed us to analyze the different magnitudes of the drop in vertical total electron content (ΔVTEC) with varying occultation percentages. We found an expected reduction in this drop as we move away from totality path but we also detected a new increment in ΔVTEC as we got closer to Earth’s Magnetic Equator. We also compared our observations of the geomagnetic field variations with predictions that were based on the Ashour-Chapman model and we find an overall good agreement, although a ≈20 min delay with the eclipse maximum is evident beyond observing uncertainties. This suggests the presence of processes that delay the response of the lower ionosphere to the loss of the photoionization flux.

scholarly journals Types of pulsating aurora: comparison of model and EISCAT electron density observations

2022 ◽  
Vol 40 (1) ◽  
pp. 1-10
Author(s):  
Fasil Tesema ◽  
Noora Partamies ◽  
Daniel K. Whiter ◽  
Yasunobu Ogawa
Keyword(s):  
Energetic Particle ◽  
Energy Deposition ◽  
Radar System ◽  
Ion Chemistry ◽  
Satellite Measurements ◽  
Electron Densities ◽  
Incoherent Scatter ◽  
Significant Difference ◽  
Energetic Particle Precipitation ◽  
Good Agreement

Abstract. Energetic particle precipitation associated with pulsating aurora (PsA) can reach down to lower mesospheric altitudes and deplete ozone. It is well documented that pulsating aurora is a common phenomenon during substorm recovery phases. This indicates that using magnetic indices to model the chemistry induced by PsA electrons could underestimate the energy deposition in the atmosphere. Integrating satellite measurements of precipitating electrons in models is considered to be an alternative way to account for such an underestimation. One way to do this is to test and validate the existing ion chemistry models using integrated measurements from satellite and ground-based observations. By using satellite measurements, an average or typical spectrum of PsA electrons can be constructed and used as an input in models to study the effects of the energetic electrons in the atmosphere. In this study, we compare electron densities from the EISCAT (European Incoherent Scatter scientific radar system) radars with auroral ion chemistry and the energetics model by using pulsating aurora spectra derived from the Polar Operational Environmental Satellite (POES) as an energy input for the model. We found a good agreement between the model and EISCAT electron densities in the region dominated by patchy pulsating aurora. However, the magnitude of the observed electron densities suggests a significant difference in the flux of precipitating electrons for different pulsating aurora types (structures) observed.

Toward ionospheric tomography in Antarctica: first steps and comparison with dynasonde observations

1996 ◽  
Vol 8 (3) ◽  
pp. 297-302 ◽  
Author(s):  
J.A.T. Heaton ◽  
G.O.L. Jones ◽  
L. Kersley
Keyword(s):  
Electron Density ◽  
Total Electron Content ◽  
Satellite System ◽  
Electron Density Profile ◽  
Electron Content ◽  
Total Electron ◽  
Ionospheric Tomography ◽  
Contour Maps ◽  
Tomographic Method ◽  
Independent Observations

Total electron content (TEC) measurements obtained at two Antarctic stations over nine months beginning early in 1994 have been analysed as a first step to performing ionospheric tomography. Two receiving systems were deployed at the Faraday and Halley research stations operated by the British Antarctic Survey to monitor signals from a random selection of passes of satellites in the Navy Navigational Satellite System. The resultant measurements of total electron content have been inverted and combined with ionosonde measurements of true height and foF2 to yield two-dimensional contour maps of ionospheric electron density. In spite of the poor geometry of the observations, some 130 satellite passes were found to be suitable for reconstruction using the techniques developed for ionospheric tomography. The contour maps of plasma density have been compared with independent observations of the vertical electron density profile measured by the dynasonde ionospheric sounder located at Halley. An example is presented of a deep trough investigated by the technique, illustrating the potential of the tomographic method for study of an extended spatial region of the ionosphere over inhospitable terrain.

scholarly journals Study of TEC, slab-thickness and neutral temperature of the thermosphere in the Indian low latitude sector

2011 ◽  
Vol 29 (9) ◽  
pp. 1635-1645 ◽  
Author(s):  
K. Venkatesh ◽  
P. V. S. Rama Rao ◽  
D. S. V. V. D. Prasad ◽  
K. Niranjan ◽  
P. L. Saranya
Keyword(s):  
Early Morning ◽  
Electron Density Profile ◽  
Slab Thickness ◽  
Electron Content ◽  
Night Time ◽  
Low Latitude ◽  
Total Electron ◽  
Equatorial Station ◽  
Ionization Density ◽  
Neutral Temperature

Abstract. The ionospheric equivalent slab-thickness is an important parameter which measures the skewness of the electron density profile of the ionosphere. In this paper, the diurnal, seasonal, day-to-day and latitudinal variations of ionospheric parameters namely total electron content (TEC), the peak ionization density of F-layer (NmF2), equivalent slab-thickness (τ) and neutral temperature (Tn) are presented. The simultaneous data of GPS-TEC and NmF2 from Trivandrum (8.47° N, 76.91° E), Waltair (17.7° N, 83.3° E) and Delhi (28.58° N, 77.21° E) are used to compute the slab-thickness (τ = TEC/NmF2) of the low sunspot period, 2004–2005. The day-time TEC values at Waltair are found to be greater than those at Trivandrum, while at Delhi the day-time TEC values are much lower compared to those at Trivandrum and Waltair. The trends of variation in the monthly mean diurnal variation of TEC and NmF2 are similar at Delhi, while they are different at Trivandrum and Waltair during the day-time. The slab-thickness (τ) has shown a pre-sunrise peak around 05:00 LT at all the three stations, except during the summer months over Delhi. A consistent secondary peak in slab-thickness around noon hours has also been observed at Trivandrum and Waltair. During equinox and winter months a large night-time enhancement in the slab-thickness (comparable to the early morning peak in slab-thickness) is observed at Delhi. The latitudinal variation of slab-thickness has shown a decrease from the equatorial station, Trivandrum to the low-mid latitude station, Delhi. The neutral temperatures (Tn) computed from the slab-thickness (τ) has shown a sharp increase around 05:00 LT over Trivandrum and Waltair. Whereas at Delhi, a double peaking around 05:00 and 23:00 LT is observed during winter and equinoctial months. The neutral temperatures computed are compare well with those of the MSIS-90 model derived temperatures.

scholarly journals Intercomparisons of total electron content measurements using the Arecibo Incoherent Scatter Radar and GPS

2000 ◽  
Vol 27 (18) ◽  
pp. 2841-2844 ◽  
Author(s):  
Jonathan J. Makela ◽  
Sixto A. González ◽  
Bryan MacPherson ◽  
Xiaoqing Pi ◽  
Michael C. Kelley ◽  
...  
Keyword(s):  
Total Electron Content ◽  
Electron Content ◽  
Incoherent Scatter Radar ◽  
Total Electron ◽  
Incoherent Scatter ◽  
Scatter Radar

scholarly journals The effect of the ionosphere on ultra-low-frequency radio-interferometric observations

2018 ◽  
Vol 615 ◽  
pp. A179 ◽  
Author(s):  
F. de Gasperin ◽  
M. Mevius ◽  
D. A. Rafferty ◽  
H. T. Intema ◽  
R. A. Fallows
Keyword(s):  
Signal To Noise Ratio ◽  
Low Frequency ◽  
Systematic Errors ◽  
Electron Content ◽  
Satellite Measurements ◽  
Third Order ◽  
Low Frequencies ◽  
Total Electron ◽  
Main Driver ◽  
Systematic Effects

Context. The ionosphere is the main driver of a series of systematic effects that limit our ability to explore the low-frequency (<1 GHz) sky with radio interferometers. Its effects become increasingly important towards lower frequencies and are particularly hard to calibrate in the low signal-to-noise ratio (S/N) regime in which low-frequency telescopes operate. Aims. In this paper we characterise and quantify the effect of ionospheric-induced systematic errors on astronomical interferometric radio observations at ultra-low frequencies (<100 MHz). We also provide guidelines for observations and data reduction at these frequencies with the LOw Frequency ARray (LOFAR) and future instruments such as the Square Kilometre Array (SKA). Methods. We derive the expected systematic error induced by the ionosphere. We compare our predictions with data from the Low Band Antenna (LBA) system of LOFAR. Results. We show that we can isolate the ionospheric effect in LOFAR LBA data and that our results are compatible with satellite measurements, providing an independent way to measure the ionospheric total electron content (TEC). We show how the ionosphere also corrupts the correlated amplitudes through scintillations. We report values of the ionospheric structure function in line with the literature. Conclusions. The systematic errors on the phases of LOFAR LBA data can be accurately modelled as a sum of four effects (clock, ionosphere first, second, and third order). This greatly reduces the number of required calibration parameters, and therefore enables new efficient calibration strategies.

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