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- Title
Wavelet Analysis of Differential TEC Measurements Obtained Using LOFAR.
- Authors
Boyde, Ben; Wood, Alan; Dorrian, Gareth; Sweijen, Frits; de Gasperin, Francesco; Mevius, Maaijke; Beser, Kasia; Themens, David
- Abstract
Radio interferometers used to make astronomical observations, such as the LOw Frequency ARray (LOFAR), experience distortions imposed upon the received signal due to the ionosphere as well as those from instrumental errors. Calibration using a well‐characterized radio source can be used to mitigate these effects and produce more accurate images of astronomical sources, and the calibration process provides measurements of ionospheric conditions over a wide range of length scales. The basic ionospheric measurement this provides is differential Total Electron Content (TEC, the integral of electron density along the line of sight). Differential TEC measurements made using LOFAR have a precision of <1 mTECu and therefore enable investigation of ionospheric disturbances which may be undetectable to many other methods. We demonstrate an approach to identify ionospheric waves from these data using a wavelet transform and a simple plane wave model. The noise spectra are robustly characterized to provide uncertainty estimates for the fitted parameters. An example is shown in which this method identifies a wave with an amplitude an order of magnitude below those reported using Global Navigation Systems Satellite TEC measurements. Artificially generated data are used to test the accuracy of the method and establish the range of wavelengths which can be detected using this method with LOFAR data. This technique will enable the use of a large and mostly unexplored data set to study traveling ionospheric disturbances over Europe. Key Points: Differential Total Electron Content measurements from LOFAR are a valuable source of information on the mid‐latitude ionosphereIonospheric waves with wavelengths between 100 and 500 km can be identified using these measurementsNoise spectra are estimated to provide confidence limits for estimated wave parameters
- Subjects
EUROPE; IONOSPHERIC disturbances; GLOBAL Positioning System; IONOSPHERIC techniques; ELECTRON density; WAVELETS (Mathematics); RADIO interferometers; CONFIDENCE intervals
- Publication
Radio Science, 2024, Vol 59, Issue 4, p1
- ISSN
0048-6604
- Publication type
Article
- DOI
10.1029/2023RS007871