The paper presents the data analysis of Aerosol Optical Depth (AOD) measured from a CIMEL Sun-photometer at CSIR-Defence and Security in Pretoria, South Africa. This Aeronet instrument has been recording data since 2011 till 2018 for use in the calibration and validation process of space sensors such as earth observation satellites in space. These sensors encounter challenges while capturing...
The solar modulation of Helium isotopes (Helium-3 and Helium-4) is studied and compared to observations at the Earth. This is done from the period of minimum solar activity from 2006 to 2011, up to the period of solar maximum activity from 2012 to 2015. Computed spectra are compared to the precise measurements of Helium-3 and Helium-4 fluxes measured by the PAMELA and AMS-02 space missions...
Radiation exposure during commercial flights remains one of the dominating and inevitable factors relevant to flight personnel and passengers' health and safety. At aviation altitudes, the radiation environment that the flight personnel are exposed to, during their day-to-day occupational activities, differs significantly from terrestrial radiation received by the general population on the...
Large amplitude nonlinear soliton and supersoliton structures are investigated in three-component magnetized plasma models, consisting of inertial adiabatic ions and two-temperature electrons. We determine the existence of nonlinear structures which are propagating obliquely relative to the ambient magnetic field using the Sagdeev pseudopotential formalism in which an energy integral is...
Charged particles and plasma waves occur throughout the solar system. These particles can move slowly relative to the plasma or be accelerated to relativistic speeds by reconnection events such as solar flares. The types of waves depend on whether one considers the plasma in the solar chromosphere, solar corona, solar wind or the planetary magnetospheres. In this study we investigate the...
Observations of solar coronal loops with the Atmospheric Imaging Assembly (AIA) instrument of SDO have revealed the existence of a low amplitude decay-less regime of transverse oscillations. These appear to be like the well understood large amplitude and rapidly decaying fast kink-mode oscillations observed in loops, but their means of excitation and exact nature are still debated. Addressing...
We present first observation of climatology of nighttime thermospheric neutral winds between
February 2018 and January 2019 measured by a Fabry-Perot interferometer (FPI) located in
Sutherland, South Africa (32.2◦S, 20.48◦E; geomagnetic latitude: 40.7◦S). This FPI measures the
nighttime oxygen airglow emission at 630.0 nm, which has a peak emission at an altitude of
roughly 250 km. The...
Daily solar radiation (DSR) is sparsely measured in meteorological stations in South Africa. The prediction of DSR is very crucial to solar energy conversion systems (design, modeling, and operation) as well as decision making of potential energy policies. The need for these solar system designs vary from the use of power and water supply for industrial purposes to agricultural and domestic...
The observations of large-scale travelling ionospheric disturbances (TIDs) originating from high latitude, and crossing the equator into the other hemisphere in the African-European sector, during geomagnetically quiet conditions within the period of 2010-2018. For each month, the four international geomagnetically quiet days were selected. The Global Navigation Satellite Systems (GNSS) total...
An important service that Space Weather Centres offer is HF propagation predictions for use by airlines, other users of long-distance radio communication and, especially, in the case of the military. One aim of this project is to report on the verification of Maximum Usable Frequency (MUF) predictions, given by the Ionospheric Communication Enhanced Profile Analysis and Circuit Prediction...
The study of sunspot rotation is a mature subject that has been investigated both theoretically and observationally. Sunspot rotation is recognised as an important mechanism for depositing energy into the Sun’s atmosphere. An understanding of the characteristics of this energy input is important, because this energy may be transported and stored in the solar atmosphere, effectively enhancing...
Accelerated particles in flaring loops are confined by both pitch-angle scattering and the converging of magnetic fields to the loop endpoints, i.e. magnetic mirroring. This confinement, together with the initial pitch-angle distribution of the injected particles, govern the average escape time of particles from the loop. The escape time can give an estimate of the particle spectrum as it...
The global features of solar modulation of galactic cosmic ray proton in the heliosphere are studied with a comprehensive three-dimensional numerical model and compared to proton observations made by PAMELA experiment from 2006 to 20014. The results of the numerical modelling and its comparison with observations give insight into how the elements of the diffusion and drift tensor change with...
The Super Dual Auroral Radar Network (SuperDARN) forms a global network of coherent high frequency (HF) radars located at mid- to high latitudes. Atmospheric gravity waves (AGWs) are ubiquitous throughout the atmosphere and can transport enormous energy and momentum from above or below into the mesosphere. AGWs are readily detected by HF radars as Travelling Ionospheric Disturbances (TIDs)...
