Ionosphere below 100 km: Indian measurements and models

Abstract

Several new interests relating to mesospheric ionization have emerged: one of these concerns the possible change in D region ionisation profiles (and in composition) from the coolig of the mesosphere resulting from increases in greenhouse gases. Given such interest, there is a case for a new look at the ATM approach (Adjusted Theoretical Model) on the lines introduced by Rowe et al. in 1974/1/. In this, profiles were constructed of electron density, positive ion density and positive and negative ion composition on the basis of a composite approach in which a number of constraints were defined in terms of the then existing experimental data which the models had to satisfy. This ATM approach is used to redefine the constraints using a number of rocket D region profiles collected from Thumba over the last three decades. These resulted in changes in the key parameters that enter into the six-ion theoretical model. Comparisons are also shown between the observed D region profiles and the IRI profiles for similar conditions: IRI electron density values are found to be systematically larger than Thumba Rocket values.