Studies on Ionospheric D & E Region Models in Conjunction with Al Absorption Measurements at Waltair

Abstract

Ionospheric absorption has been studied in model ionospheric layers at Waltair using Sen-Wyller's fully generalized magneto-ionic theory. On the basis of numerical calculations a suitable model is selected that gives values of absorption, virtual height and the cos <img src='/image/spc_char/lembda.gif' border=0> index <i>n </i> in reasonable agreement with the experimentally observed values from Al absorption data. It is found that 'the assumption of a single Chapman layer model along with an exponential collision frequency profile leads to a cos <img src='/image/spc_char/lembda.gif' border=0> index less than 1.5In particular. a three-tier model of electron density profile consisting of (i) a Chapman type <i>E</i>(<i>N</i>_e0 = 2 x 10⁵ cm^-3 and <i>h</i>₀<i> =</i> 110 km) and a Chapman type <i>D(N</i>_e0<i>= </i>10³ cm^-3 and <i>h</i>₀= 75 km); (ii) a constant electron density lower D-region <i>(N</i>_e= 200 cm^-3 in the height range 50-70 km) with a uniform scale height of 6 km, and (iii) an exponential collision frequency profile assuming the value of v₀ -= 2 X 10⁴ sec^-1 at 110 km, is proposed.