Modelling and Analysis of POGS Data over Southern Africa by Spherical Cap Harmonic Analysis

Abstract

POGS total intensity data were analysed over the Southern African region between 10° South and 45° South in latitude and between 5° East and 40° East in longitude. Satellite data were selected corresponding to magnetically quiet conditions during local night times before carrying out an analysis of external fields by subdividing winter and summer data into Dst bins 5 nT wide, centred at multiples of 5 nT. Spherical Cap Harmonic Analysis (SCHA) was then applied to each of these Dst data bins to obtain external field coefficients corresponding to k = 1. Residual POGS data were downward continued by means of the equivalent layer magnetization model and modelled by SCHA to reveal component data at ground level.