Premium
Validation of ROTI for Ionospheric Amplitude Scintillation Measurements in a Low‐Latitude Region Over Africa
Author(s) -
Olwendo J. O.,
Cilliers Pierre,
Weimin Zhen,
Ming Ou,
Yu Xiao
Publication year - 2018
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/2017rs006391
Subject(s) - scintillation , interplanetary scintillation , ionosphere , amplitude , physics , satellite , environmental science , remote sensing , computational physics , geodesy , optics , geology , geophysics , nuclear physics , detector , astronomy , solar wind , plasma , coronal mass ejection
Measurement of the effect of ionospheric irregularities on Global Navigation Satellite Services has drawn great interest due to the adverse effects of such irregularities on precise position estimation. Specialized receivers are currently being used to measure the effects of ionospheric irregularities on the satellite signals. These effects are characterized by the amplitude scintillation index S 4 and the phase scintillation index σ Φ (sigma phi). In order to compute these scintillation indices, one requires a receiver that measures data at a high sampling rate. The intensity of ionospheric scintillation is an important parameter in the modeling of ionospheric scintillation. Therefore, an index is required that accurately reflects the amplitude scintillation as conventionally measured by means of the S 4 index. To infer the characteristics of ionospheric irregularities from ionospheric scintillation related to geophysical processes, the choice of sampling rate is very important, especially for small‐scale phenomena. In this work, we used a Global Positioning System receiver with high sampling rate, sampling at 20 Hz to compute both the amplitude scintillation index S 4 and the rate of change of total electron content index (ROTI) based on relative total electron content. The results show that by scaling the ROTI values using an appropriate scaling factor, a scintillation index can be calculated that correlates well with the amplitude scintillation index S 4 , for values of S 4 < 0.4. For strong scintillation events S 4 > 0.5, the scaled ROTI values are more sensitive for events that lead to loss‐of‐lock (as evidenced by jumps in the L1‐phase values) than the S 4 index. It is also shown that the choice of sampling interval may affect the computed ROTI at a particular location.