On the EFFECTS of SCINTILLATION  on the TRANSIONOSPHERIC PATHS of PROPAGATION 
Nikolay N.Zernov, V.E.Gherm, H.J.Strangeways 
 
As is well known scintillation of the electron density of the ionosphere 
essentially affects navigation and other Earth-satellite telecommunication 
links. In the extreme cases this may even result in loss of the phase lock and, 
finally, in full degradation of a link of communication. It is a special case 
for consideration the occurrence of local mid-scale inhomogeneities in the 
ionosphere. Patches, arches, or blobs in the high-latitude ionosphere, or 
bubbles in the low-latitudes may cause strong enhancement of the level of 
scintillation, characterized by the values of scintillation index S4, which may 
well be within the range typical for strong scintillation. The St.Petersburg 
(Russia) Leeds (UK) scintillation propagation model, developed initially for 
the case of smoothly inhomogeneous background ionosphere, which does not contain 
the mid-scale local inhomogeneities, is well appropriate for describing these 
situations, including the case of strong scintillation and the values of the 
fractional electron density up to 100% for the working frequencies 
of 1GHz and above [1]. This turns out to be possible as, according to our 
estimates, at the frequencies of this range the regime of strong scintillation 
never arises inside the ionospheric layer. Therefore, the perturbation theory 
can be employed for describing the propagation in the ionosphere, and the field 
immediately below the ionosphere can be constructed. To convey this field down 
to the Earth’s surface the general theory of a random screen is then used. We 
call this approach as the hybrid scintillation propagation model. 
       Recently the hybrid model has been further extended to enable description 
of the effects due to local mid-scale ionospheric inhomogeneities, e.g. bubbles 
of the low-latitude ionosphere [2], or patches in high latitudes [3]. This 
latter case [2,3] essentially differs from the effects in the mid-latitude 
ionosphere by the circumstance that the presence of moving local inhomogeneities 
makes the stochastic signal essentially statistically non-homogeneous, so that 
the hybrid propagation model was to be significantly elaborated. In the 
presentation recent results of modelling of the scintillation effects due to 
mid-scale inhomogeneities of the low-latitude and high-latitude ionosphere will 
be presented. 
 
1.V.E.Gherm, N.N.Zernov, and H.J.Strangeway, Radio Science, 40(1), RS1003, doi: 
10.1029/2004RS003097, 2005. 
2. V.E.Gherm, N.N.Zernov, and H.J.Strangeways, International Beacon Satellite 
Symposium, Boston, USA, 11-15 June, 2007. Published on conference CD. 
3. S.A. Maurits, V.E. Gherm, N.N. Zernov, and H.J.Strangeways, Radio Science, 
paper #2006RS003539R, accepted in December, 2007.