Minimum variance technique for the analysis of ionospheric data acquired in satellite retarding potential analyzer experiments

Abstract

A minimum variance iterative technique for the determination of ionospheric parameters, including electron and ion temperatures and densities, is presented. The method formally incorporates a priori information regarding the values of these parameters and, in particular, whatever information the experimenter has concerning the uncertainty associated with these values. With proper use of this additional information, convergence will be more rapid and more likely than would be the case were a priori information not employed. With certain mathematical models, singularities that occur in other techniques are avoided. In addition, procedures for generating nominal parameter estimates from the data have been devised. These techniques have been developed for, and lend themselves to, the automatic processing of large quantities of data. An example of the analysis of both ion and electron data is included for illustrative purposes.

Diurnal, seasonal and latitudinal variations of ion temperature measured by the SROSS C2 satellite in the Indian zone equatorial and low latitude ionosphere and comparison with the IRI

“…Di erent ion species are retarded at di erent voltages and a positive retarding voltage sweep will result in the decrease of ion current at di erent voltages corresponding to various ion masses, giving rise to a composite I -V curve. The ion current reaching the sensor in response to the retarding voltage is governed by the equation (adapted from Moss and Hyman, 1968)…”

Electron and ion temperatures in the ionosphere

“…The procedure, which is much -moredifficult than for the spherical probe, has been described by Moss and Hyman (1968) and by Patterson (1969).…”

Evaluation of the ion-density measurements by the Indian satellite SROSS-C2

“…Assuming that all the wires in different grids used in the sensor (4 × 50 mesh and 2 × 100 mesh) are completely misaligned, the minimum value of optical transparency factor comes out to be 42%. But because perfect misalignment of grid wires is never possible in reality, an efficiency factor of 0.5, as used by Moss and Hyman [1968], was assigned to η . The relationship between the current and the retardation voltage represented by was used to recover the ion parameters of density and temperature from the I‐V curve using nonlinear least squares fitting technique [ Garg et al , 2003, and the references therein].…”