Linear Vary-Chap Topside Electron Density Model with Topside Sounder and Radio-Occultation Data
- 294 Downloads
The Linear Vary-Chap function has received increased attention in describing the topside ionosphere due to its good performance for predicting and extrapolating radio-occultation (RO) electron density ionospheric profiles. The systematic increase in the scale height is consistent with first principles corresponding to the increase in the electron temperature; however, the altitude where the linear scale height approximation does not stay valid has not been explicitly discussed in the literature. In order to demonstrate up to what extent the linear behavior of the scale height is still valid, this work analyzes more than 50,000 manually scaled ionospheric profiles measured by topside sounders on board Alouette and International Satellites for Ionospheric Studies satellites. Based on this initial analysis, a new topside model is proposed to take into consideration the nonlinear behavior of the topside scale height. The proposed climatological model, a fit of spherical harmonics to parameters derived from topside RO profiles, is used to predict topside sounder measurements. An assessment of the predicted, RO-derived, topside is carried out and the experimental results are discussed in order to show the viability of extrapolating RO ionospheric profiles for altitudes above the low Earth orbit.
KeywordsChapman function Scale height Ionospheric profile ISIS Alouette COSMIC/FORMOSAT-3
This work was jointly funded by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP Grants: 2015/15027-7 and 2016/22011-2) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq Grants: 429885/2016-4, 310829/2017-8 and 309832/2016-0). The authors are grateful to UCAR (USA) and NSPO (Taiwan) for providing FORMOSAT-3/COSMIC RO data.
- Fonda C, Coisson P, Nava B, Radicella SM (2005) Comparison of analytical functions used to describe topside electron density profiles with satellite data. Ann Geophys 48:491–495Google Scholar
- Hernández-Pajares M, Garcia-Fernàndez M, Rius A, Notarpietro R, von Engeln A, Olivares-Pulido G (2017) Electron density extrapolation above F2 peak by the Linear Vary-Chap model supporting new global navigation satellite systems-LEO occultation missions. J Geophys Res Space Phys 122:9003–9014CrossRefGoogle Scholar
- Kelley MC (2009) The Earth’s ionosphere: plasma physics and electrodynamics. Academic Press, Burlington, p 576Google Scholar
- Lei J, Syndergaard S, Burns AG, Solomon SC, Wang W, Zeng Z, Roble RG, Wu Q, Kuo Y-H, Holt JM, Zhang S-R, Hysell DL, Rodrigues FS, Lin CH (2007) Comparison of COSMIC ionospheric measurements with ground-based observations and model predictions: preliminary results. J Geophys Res 112:A07308Google Scholar
- Liu L, Le H, Chen Y, He M, Wan W, Yue X (2011) Features of the middle- and low-latitude ionosphere during solar minimum as revealed from COSMIC radio occultation measurements. J Geophys Res 116:A09307Google Scholar
- Llewellyn SK, Bent RB (1973) Documentation and description of the bent ionospheric model (Report AFCRL-TR-73-0657). Hanscom AFB, MassGoogle Scholar
- Prol FS, Hernández-Pajares M, Camargo PO, Muella MTAH (2018) Spatial and temporal features of the topside ionospheric electron density by a new model based on GPS radio occultation data. J Geophys Res Space Physics 123:2104–2115Google Scholar
- Rishbeth H, Garriott OK (1969) Introduction to ionospheric physics. Academic Press, New YorkGoogle Scholar
- Themens DR, Jayachandran PT, Bilitza D, Erickson PJ, Häggström I, Lyashenko MV, Reid B, Varney RH, Pustovalova L (2018) Topside electron density representations for middle and high latitudes: a topside parameterization for E-CHAIM based on the NeQuick. J Geophys Res Space Phys 123:1603–1617CrossRefGoogle Scholar
- Zhao B, Wan W, Yue X, Liu L, Ren Z, He M, Liu J (2011) Global characteristics of occurrence of an additional layer in the ionosphere observed by COSMIC/FORMOSAT-3. Geophys Res Lett 38:L02101Google Scholar