Ionospheric specification with analytical profilers: Evidences of non-Chapman electron density distribution in the upper ionosphere

Verhulst, Tobias; Stankov, S. M.

doi:10.1016/j.asr.2014.10.017

Cited by 12 publications

(4 citation statements)

References 31 publications

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“…Verhulst and Stankov (, ) compared α‐Chapman, β‐Chapman, Epstein, and exponential topside profiles (calculating for each of these a different effective scale height) to topside sounders data, finding that in almost 75% of the analyzed cases the best fit was provided by the exponential profile, followed by the α‐Chapman profile. Local time, seasonal, latitudinal, longitudinal, solar, and geomagnetic activity influence on the topside profile shape were also identified but highlighting at the same time an objective difficulty in modeling the effective scale height dependence on these parameters.…”

Section: Introductionmentioning

confidence: 99%

“…More obvious relations were instead identified between the profile shape and the characteristics associated to the F 2 layer peak (basically hmF 2 and NmF 2), whose variations strongly influence the topside profile. Verhulst and Stankov (, ) also stressed the fact that using a single profile for every geophysical condition and for the entire topside profile could lead to a misrepresentation, underlining that a two‐layer profile composed by an α‐Chapman function for the lower part of the topside region (from hmF 2 to about 400 km of height) and an exponential function for the upper part (from 400 km to the upper transition height) could better describe the topside ionosphere.…”

Section: Introductionmentioning

confidence: 99%

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Modeling the Lower Part of the Topside Ionospheric Vertical Electron Density Profile Over the European Region by Means of Swarm Satellites Data and IRI UP Method

2018

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An empirical method to model the lower part of the ionospheric topside region from the F2 layer peak height to about 500–600 km of altitude over the European region is proposed. The method is based on electron density values recorded from December 2013 to June 2016 by Swarm satellites and on foF2 and hmF2 values provided by IRI UP (International Reference Ionosphere UPdate), which is a method developed to update the IRI model relying on the assimilation of foF2 and M(3000)F2 data routinely recorded by a network of European ionosonde stations. Topside effective scale heights are calculated by fitting some definite analytical functions (α‐Chapman, β‐Chapman, Epstein, and exponential) through the values recorded by Swarm and the ones output by IRI UP, with the assumption that the effective scale height is constant in the altitude range considered. Calculated effective scale heights are then modeled as a function of foF2 and hmF2, in order to be operationally applicable to both ionosonde measurements and ionospheric models, like IRI. The method produces two‐dimensional grids of the median effective scale height binned as a function of foF2 and hmF2, for each of the considered topside profiles. A statistical comparison with Constellation Observing System for Meteorology, Ionosphere, and Climate/FORMOsa SATellite‐3 collected Radio Occultation profiles is carried out to assess the validity of the proposed method and to investigate which of the considered topside profiles is the best one. The α‐Chapman topside function displays the best performance compared to the others and also when compared to the NeQuick topside option of IRI.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modeling the Lower Part of the Topside Ionospheric Vertical Electron Density Profile Over the European Region by Means of Swarm Satellites Data and IRI UP Method

2018

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“…The α ‐Chapman profile with variable scale heights was also proposed as a possible choice for the topside profile model [ Reinisch et al ., ; Nsumei et al ., ]. Verhulst and Stankov [, ] found that the best fit for the empirical modeling of the electron density profile in the topside ionosphere is the exponential profile with data recorded by the topside sounders on board the Alouette and ISIS satellites, followed by the Chapman profile. In the topside ionosphere where it is one or two scale heights higher than the F 2 layer peak at middle latitudes, the diffusion equation (or the exponential profile) is probably more suitable than the Chapman profile.…”

Section: Physical Interpretationmentioning

confidence: 99%

Statistical behavior of the longitudinal variations of daytime electron density in the topside ionosphere at middle latitudes

Wang

Burns

et al. 2016

JGR Space Physics

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Electron density in the topside ionosphere has significant variations with latitude, longitude, altitude, local time, season, and solar cycle. This paper focuses on the global and seasonal features of longitudinal structures of daytime topside electron density (Ne) at middle latitudes and their possible causes. We used in situ Ne measured by DEMETER and F2 layer peak height (hmF2) and peak density (NmF2) from COSMIC. The longitudinal variations of the daytime topside Ne show a wave number 2‐type structure in the Northern Hemisphere, whereas those in the Southern Hemisphere are dominated by a wave number 1 structure and are much larger than those in the Northern Hemisphere. The patterns around December solstice (DS) in the Northern Hemisphere (winter) are different from other seasons, whereas the patterns in the Southern Hemisphere are similar in each season. Around March equinox (ME), June solstice (JS), and September equinox (SE) in the Northern Hemisphere and around ME, SE, and DS in the Southern Hemisphere, the longitudinal variations of topside Ne have similar patterns to hmF2. Around JS in the Southern Hemisphere (winter), the topside Ne has similar patterns to NmF2 and hmF2 does not change much with longitude. Thus, the topside variations may be explained intuitively in terms of hmF2 and NmF2. This approach works reasonably well in most of the situations except in the northern winter in the topside not too far from the F2 peak. In this sense, understanding variations in hmF2 and NmF2 becomes an important and relevant subject for this topside ionospheric study.

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“…Belehaki and Tsagouri [2002] utilized Huang and Reinisch method to investigate the contribution of bottomside TEC to the full TEC in the ionosphere during several weak and moderate storms over Athens. Although the applicability of the extrapolated topside ionospheric profile was examined in many studies under the quiet time condition [e.g., Reinisch et al, 2007;Stankov et al, 2003;Verhulst and Stankov, 2015], whether the ionosonde topside profile is suitable for the storm study is not addressed. Astafyeva, 2009;Lei et al, 2014Lei et al, , 2015Astafyeva et al, 2015].…”

Section: Introductionmentioning

confidence: 99%

Contribution of the topside and bottomside ionosphere to the total electron content during two strong geomagnetic storms

et al. 2016

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In this study, the ionospheric observations from ionosondes, GPS receivers, and incoherent scatter radars (ISR) at low and middle latitudes were used to investigate the contribution of the bottomside and topside ionosphere to the total electron content (TEC) during the September 2005 and December 2006 geomagnetic storms. It was found that the contribution of the bottomside TEC below F2 peak (BTEC) to the ionosonde ionospheric TEC (ionosonde ITEC), namely, BTEC/ITEC was almost constant during both quiet and storm times, while the ratio of BTEC to GPS TEC (i.e., BTEC/GPS‐TEC) underwent obvious diurnal variations at all stations. The BTEC/GPS‐TEC during the positive phase was similar to that during quiet time, regardless of the formation mechanisms of the observed positive phases. Moreover, our analysis revealed that the ISR calculated BTEC/ITEC during positive ionospheric phases was comparable to that during quiet time. This suggests that the positive phases in these two events mainly occurred around the F2 peak height. There were large differences between the calculated BTEC/ITEC from the ISR observations and BTEC/GPS‐TEC during the negative phase or at night when the plasmasphere possibly contributed significantly to the TEC in the relative sense. Although the absolute changes of the topside TEC were larger than the bottomside TEC at low and middle latitudes associated with the larger topside effective ionospheric thickness, unlike the October 2003 superstorms, the relative changes of the topside TEC to the quiet time reference in these two strong storms were not greater than the changes of the bottomside TEC and peak density NmF2.

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Ionospheric specification with analytical profilers: Evidences of non-Chapman electron density distribution in the upper ionosphere

Cited by 12 publications

References 31 publications

Modeling the Lower Part of the Topside Ionospheric Vertical Electron Density Profile Over the European Region by Means of Swarm Satellites Data and IRI UP Method

Modeling the Lower Part of the Topside Ionospheric Vertical Electron Density Profile Over the European Region by Means of Swarm Satellites Data and IRI UP Method

Statistical behavior of the longitudinal variations of daytime electron density in the topside ionosphere at middle latitudes

Contribution of the topside and bottomside ionosphere to the total electron content during two strong geomagnetic storms

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