An overview of methodologies for real-time detection, characterisation and tracking of traveling ionospheric disturbances developed in the TechTIDE project | Journal of Space Weather and Space Climate

Topical Issue - Scientific Advances from the European Commission H2020 projects on Space Weather

Open Access

Table 1

TechTIDE detection methodologies for TIDs.

Detection method and main characteristics	Products
Methods specific to the detection of LSTIDs
*HF-TID*	European map indicating the velocity, amplitude and propagation direction at the reflection points between Digisondes operated in bistatic mode. Report of TID characteristics extracted from the analysis of the raw data from the D2D operations, i.e TID propagation Doppler frequency, angle of arrival, and time-of-flight from Tx to Rx, both OI and VI sounding. Plots of amplitude, Doppler, azimuth within the last 45 min from the TID detection.
Input: Signal properties from Digisonde synchronized operation.
Output: TID velocity, amplitude, propagation direction at the signal reflection point between the stations.
The method is fully described in the paper by Reinisch et al. (2018).
*HF interferometry*	Dominant period, amplitude and horizontal vector velocity of detected LSTID over the region of interest and over each Digisonde location.
Input: Ionospheric characteristics from VI and OI soundings.
Output: 2D TID vector velocity, amplitude, period and spectral energy contribution.
The method is described in the paper by Altadill et al. (2020a) while the calculation of the corresponding activity levels is given in the TechTIDE project report by Altadill et al. (2020b).
*1D version of TaD-EDD model – LSTID index*	LSTID index: The residuals of the detrended electron density from the median values, calculated with the TaD model for heights ranging from 150 up to 900 km with 50 km step. The results are provided over specific European Digisondes performing VI sounding at least every 5 min.
Input: Ionospheric characteristics at the hmF2 altitude and TEC maps.
Output: Analytical function of the electron density distribution with altitude from 90 km to 22,000 km.
The method is first proposed by Belehaki et al. (2017).
Methods specific to the detection of MSTIDs
*CDSS-MSTID*	Period, amplitude of Doppler measurements, observed horizontal velocities and azimuths of MSTIDs.
Input: CDSS reflected signals, ionospheric characteristics and irregularities.
Output: Doppler shift, Doppler shift. Fluctuations associated to the TIDs and estimation of the propagation parameters (direction, velocity, and amplitude).
The method is fully described in the paper by Chum & Podolská (2018).
*Spatial & temporal GNSS analysis*	MSTID index calculated at each GNSS contributing receiver.
Input: GNSS TEC from single receivers over a region.
Output: Fluctuations associated to the TIDs and estimation of the propagation parameters (direction, velocity, and amplitude).
The method is first proposed by Hernández-Pajares et al. (2006).
Indicators
*GNSS TEC gradient*	Maps of TEC gradients for the European region
Input: Grids of TEC maps over a region.
Output: Latitude-time maps of TEC gradients and indication of significant gradients.
The method is described in the paper by Borries et al. (2017).
AATR indicator	Along Arc TEC Rate (AATR) calculated at each contributing GNSS receiver.
Input: Slant TEC parameters.
Output: The along Arc STEC Rate, metric to characterize the ionosphere operational conditions of EGNOS.
The method is described in the paper by Juan et al. (2018).
Ionospheric background conditions	Maps of relative standard deviation of the electron density at each ionospheric altitude with an indication of the probability for LSTIDs detection.
Input: Ionogram derived characteristics in the F2 layer from ionosondes; GNSS TEC at the ionosonde location; geomagnetic, and solar flux indices.
Output: Maps of the electron density at any height in the bottomside and topside ionosphere.
The methodologies that define ionospheric background conditions are described in the TechTIDE project report by Tsagouri et al. (2018a).

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