TNA Project Overview

PITHIA-NRF is a project aiming at building a distributed network in Europe integrating observation facilities, data processing tools and prediction models for ionososphere, thermosphere and plasmasphere research. The project includes a Transnational Access (TNA) programme providing external researchers access to PITHIA-NRF connected research facilities and expertise. A short description of the TNA projects and their status is given below.


TNA round Primary NODE Name Project title Status
TNA1 EISCAT Alireza Mahmoudian Detailed Investigation of Dust Charging in the PMSE Source Region Postponed
(technical reasons)
Affiliation: University of Tehran, Iran

Abstract: A new technique for investigating dust charging in the PMSE (polar mesospheric summer echoes) source region is proposed and discussed in our recent work at EISCAT (European Incoherent Scatter Scientific Association) through collaboration with Dr. Kosch at the University of Lancaster (Mahmoudian et al., 2020). We employed the first high-frequency (HF) modulation of the PMSE with varying pump power during 2019 campaign at EISCAT. Two experiment setups including HF pump power stepping as well as quasi-continuous power sweeping were used. The experiment was designed based on a computational mode capable of simulation of PMSE evolution during HF pump modulation in order to develop a new approach for studying the dust charging process in the PMSE source region. The charge state of dust particles along with background dusty plasma parameters is estimated using the experimental and computational results. We have designed a detailed future experiment based on background dusty-plasma parameters. We propose to conduct this experiment that can be a breakthrough for investigating exact dust charge state in space for the first time. Mahmoudian, A., Kosch, M. J., Vierinen, J., & Rietveld, M. T. (2020). A new technique for investigating dust charging in the PMSE source region. Geophysical Research Letters, 47, e2020GL089639.

UPC—ionSAT Anna Morozova Portuguese regional ionosphere maps – PRIMA Finished
Affiliation: University of Coimbra, Instituto de Astrofísica e Ciências do Espaço

Abstract: Instituto de Astrofísica e Ciências do Espaço at the University of Coimbra (IA-UC) has a small group (and only one working permanently on this subject in Portugal) of researchers working in the area of ionospheric studies. To the moment no systematic studied of ionospheric response to space weather disturbances (i.e., disturbance of the solar and magnetospheric origin) were performed for Portuguese regions, neither Continental nor Insular (Azores and Madeira). One of the reasons is the lack of good quality data. Thus, the compilation of a database of ionospheric parameters including the total electron content (TEC) for the whole Portuguese region will be a necessary step for any study: data analysis, development of regional models to predict ionospheric response to different space weather events, development of regional ionospheric maps or other products that can be used by national service providers and end users.

Significant amount of the GNSS data from the Portuguese geodetic GNSS networks (as RAEGE-Az and RENEP) cannot be added to a such database because these data are available only as GNSS raw or pre-processed data formats (e.g., RINEX) and have to be converted to TEC data. Unfortunately, IA-UC team members did not have sufficient experience in such data processing. The PITHIA-TNA call was a perfect opportunity for the IA-UC team members to obtain new knowledge working in collaboration with the UPC-IonSAT team that has extensive experience in collecting and processing GNSS data from different GNSS systems.As a result of the collaboration with UPC-IonSAT team, the IA-UC team obtained necessary knowledge and software to process the files and significantly enlarged the Portuguese ionospheric parameters database using high quality data from the Azores Archipelago. The new data allowed to perform comparative studies of ionospheric disturbances observed during geomagnetic storms at different longitudinal sectors.Also, the UPC-IonSAT team agreed to support the IA-UC team in a planned development of RIMs for Portugal using data from RENEP and RAEGE-Az GNSS networks. The IA-UC will submit a project to a Portuguese national call for research projects in summer 2023 with UPC-IonSAT team members as advisors/consultants of the project.

EISCAT Ashik Paul Study of the characteristics of ionospheric irregularities at high and low latitudes through coordinated observations of EISCAT and VHF Radar at Haringhata, India Finished
Affiliation: University of Calcutta
Abstract: University of Calcutta is developing a high power fully-active phased-array radar at 53MHz at Haringhata, India situated near the northern crest of the Equatorial Ionization Anomaly (EIA). The location of this radar is unique being the only one at this frequency in the south-east Asian longitude sector. Within the framework of the PITHIA-NRF TNA access project, the University of Calcutta ST Radar team was given online training at EISCAT on introduction, data format, analyses and some interpretation of the radar during April through September 2022. A number of sessions were organised wherein after the initial few meetings, specific cases (based on used cases as well as recent event) of Space Weather impact on the ionosphere were focused on and intensive analyses were conducted using the EISCAT radar as well as other satellite data from different latitude sectors which were presented by the University of Calcutta project team. This is planned to be the first step in the training process to be followed by physical access and conducting coordinated experiments using the EISCAT and University of Calcutta VHF Radar through a future TNA call.

Kasper van Dam, Eelco Doornbos

Comparing Dutch GNSS-receiver measurements to INGV (and DLR) model data Finished
Affiliation: KNMI

Within the Trans-National Access programme of the PITHIA-NRF framework dr. Doornbos and dr. Van Dam from KNMI have visited INGV between 21–25 March 2022 to work with dr. Cesaroni and dr. Spogli on ionosphere measurements. This report describes the outcomes of this visit. The goal of the project is to compare KNMI’s GNSS receiver data in the Caribbean with INGV and DLR data, and to learn about INGV data calibration techniques. Both objectives have been met. Using INGV calibration software the receiver output has been validated and some first scientific results have been obtained. These include observing ionospheric disturbance due to the Tonga volcanic eruption and observing the ionospheric response to a solar flare. As of 5 May 2022 KNMI’s scintillation data is shared with INGV as the receivers increase the global coverage of the INGV network which is used in the PECASUS collaboration (in which KNMI also participates). Plans for future collaboration have been discussed.

IAP Kateryna Axonova Longitudinal differences in traveling ionospheric disturbance characteristics at midlatitudes – LONG Finished
Affiliation: Institute of Ionosphere

Abstract: This project aims at identifying longitudinal differences in traveling ionospheric disturbance (TID) characteristics for two midlatitude ionospheric stations located near Pruhonice, Czech Republic (50.0 N, 14.5 E) and Kharkiv, Ukraine (49.6 N, 36.3 E) and having very close latitudes. In most cases, daytime TIDs are associated with acoustic gravity waves (AGWs). Since most of the AGWs in the ionosphere originate from the lower atmosphere, this project mainly focuses on regional features of TID propagation due to the different meteorological or ground conditions immediately beneath the local ionosphere. Using the combination of the different techniques (ionosondes, incoherent scatter and Doppler radars), the following TID parameters will be determined or estimated: diurnal occurrence at each location; predominant period, vertical and horizontal phase velocity and wavelength, relative amplitude of electron density fluctuations. This project will enable enhancing our knowledge of regional behavior of TID characteristics and improving prediction capabilities of ionosphere models.

The overall objectives of this project are focused on: detection of longitudinal densities in TID parameters for stations close in latitude and different in longitude; daily dependencies in TID parameters; influence of magnetic activity on TID parameters.
UPC-IonSAT Nataliya Porayko Magneto-ionospheric modelling through Faraday rotation in Pulsar data Finished
Affiliation: MPIfr Bonn
Abstract: Faraday rotation of pulsar signals provides information on the electron densities and magnetic fields in the intervening plasma. In order to access the astrophysical contribution to Faraday rotation, one needs to correct for the time-variable effect of the terrestrial magneto-ionic matter, namely ionosphere and plasmasphere. In this work, we compare the performance of three models of the ionosphere using observations of the source PSR~J0332+5434 taken with the LOw Frequency ARray (LOFAR). All considered models use Global Navigation Satellite System (GNSS) data for electron density reconstruction. As shown in Porayko et al. 2019, the conventional single layer model is not capable of fully accounting for the ionospheric Faraday rotation in pulsar data. For the first time, the single layer model improved with an extended electron density profiles taken from the IRI-Plas (International Reference Ionosphere and Plasmasphere) empirical model, and the dual-layer voxel TOmographic data-driven Model of the Ionosphere (TOMION) has been tested for the first time with pulsar observations. Although the last two improve the reconstruction of the ionospheric Faraday rotation, none of the considered models completely purge the observed systematics. We demonstrated that LOFAR pulsar data is a powerful tool to test and improve magetoionic modeling of the Earth's atmosphere. Within the TNA program of PITHIA-NRF the multifaceted collaboration between three institutes, namely MPIfR, ASTRON and UPS-IonSAT, has been established. The MPIfR and ASTRON provided the high-cadence LOFAR pulsar data and subsequent observational expertise. While the specialists from the UPC-IonSAT shared the complete tomographic solutions of the TOMION model of the ionosphere and provided the usage guideline. The progress on the project has been monitored through the regular online meetings.The paper has been submitted to the Journal of Geodesy based on the results of this program. The project results have been disseminated on a number of international conferences.
NOA Veronika Barta Wave-like structures in the IONosphere between Athens and Sopron Prolonged (technical reasons)
Affiliation: Institute of Earth Physics and Space Science (ELKH EPSS)
Abstract: The aim of the project is to detect TIDs what are related to wave structures propagating within the ionosphere above South-East Europe using high cadence campaign measurements. Ionosonde measurements - skymaps and D2D measurements between Athens and Sopron - will be analyzed. The geographical location of the two stations provides a unique opportunity to study wave-like ionospheric anomalies in the South-East European region.
EISCAT Viktor Tashlykov Verification of the IISR analysis software on the EISCAT data Postponed (subject to change in political situation)
Affiliation: Institute of Solar-Terrestrial Physics SB RAS
Abstract: For Irkutsk Incoherent scatter radar, (IISR) there is a scientific problem still fully unsolved: estimation of ion temperatures through backscatter signal analysis. The main difficulty is that Irkutsk radar antenna system can transmit and receive signal of strictly linear polarization. Receiving signal of single linear polarization means systematic fadings in power profile due to Faraday effect with no available information on the orthogonal polarization. Development of the technique for plasma parameters estimation in application to Irkutsk IS radar is the key theme of my PhD thesis in the works. Currently designed for Irkutsk IS radar on the basis of open source software, the algorithm for plasma temperatures recovery needs verification and testings. That can be done in two ways. First, by adapting GUISDAP to Irkutsk radar signal peculiarities and applying it to the IISR data. Second, by applying the IISR analysis software to the EISCAT data. Comparison of the results in both cases can give us valuable view on current state and prospects of the IISR analysis software. The final objective of this research is presenting the IISR analysis data on plasma temperatures to scientific community.
EISCAT Jean Lilensten Retrieving the ionospheric currents and magnetic field variations from the observation of the upper atmosphere emissions polarisation Finished
Affiliation: Institut de Planétologie et d'Astrophysique de Grenoble (IPAG)

In the recent years, we discovered that many nightglow emissions are polarised. This opens a new window on our space environment. In particular, it allows to follow the evolution of the electron density in the upper atmosphere, and maybe more important, the electric currents that flow either parallel or perpendicularly to the magnetic field.

The auroral latitudes constitute a major location to progress in this new approach. Up to now, the previous results could be proved only in the E-region (around 110 km height), and only with the atomic oxygen green line. Thanks to this experiment campaign, we could prove that it also works at lower altitudes (85 km) and in the F region (220 km) by observing the purple nitrogen band and the red atomic oxygen line and comparing to the EISCAT data.

TNA2 LOFAR Rositsa Miteva Study on ionospheric disturbances due to Space Weather in LOFAR data (iono-SW-LOFAR) Finished
Affiliation: Institute of Astronomy with National Astronomical Observatory - Bulgarian Academy of Sciences
Abstract: During this joint project, scientists from Bulgaria and the Netherlands investigated the effects of solar flares on the terrestrial ionosphere using the pan-European radio telescope LOFAR ( Solar flares are large explosions in the solar corona during which a large amount of energy is released, in the form of light (electromagnetic radiation from radio to X/gamma-ray range), heat, particle acceleration, mass motion and magnetic field line restructuring. In about 8 minutes after the flare, the photons arrive at Earth and can cause additional ionization of the atmospheric molecules and atoms. This perturbs the ionosphere, which, due to slight changes in the refractive index, has an effect on the radio signals, either from satellites or from cosmic radio sources going through it as well as from communication signals bouncing off the ionosphere. It has been known that the solar flares have a direct effect on the lowest (D) layer of the ionosphere, however during this project it has been shown that ionospheric disturbances can be tracked also at higher layers. With LOFAR we measure amplitude fluctuations of the signal of bright radio sources due to ionospheric scintillation. The preliminary results point towards a 3-to-6 hour delay between the flare timing and the increase of the ionospheric disturbances. The strongest flare events since 2013 have been analyzed with LOFAR data, and a large statistical study is underway.
OE Jahan Zeb Khan Thermospheric O/N2 variability and Its effects on Ionosphere during disturbed and quiet days, for solar cycles 23 and 24 In progress
Affiliation: Department of Physics, Quaid - i - Azam University Islamabad, Pakistan
Abstract: The atmosphere around the earth – based on its temperature profile – is divided into different layers, where the ionosphere is the part of an upper atmosphere that comprises an altitude of about 80-700 km. In the ionosphere many free electrons and ions with thermal energy (<1 eV) are present. The plasma of these free-charged particles is produced by the interaction of solar X-rays and Extreme Ultraviolet (EUV) radiations with neutral particles. The collision of other energetic particles with neutral, which penetrate from outer space to the ionosphere, also ionizes them. Thus, the study of the ionosphere requires knowledge of different disciplines, including atomic theory, chemical kinematics, fluid mechanics, and plasma physics (Schunk, R., and Nagy, A. 2009). In this project, we will study especially the O/N2 concentration ratio and its effects on the climatology of the Ionosphere. We have to take the O/N2 data from the different satellites at different solar activities during solar cycles 23 and 24. We then analyze and compare the monthly mean O/N2 ratio of quiet and disturbed days of SC 23 and 24, and their annual and semiannual variations with averaged NmF2 values of specified days, obtained from Ebro Observatory. This comparison will give us how O/N2 concentration controls or affects the NmF2.
OE Haixia Lyu The F2-layer peak height response at mid-latitudes to Space Hurricane Finished
Affiliation: GNSS Research Center, Wuhan University

Abstract: Space Hurricane is a large-scale magnetic vortex structure spanning the polar ionosphere and magnetosphere, which was first discovered and dubbed by the research team from Shandong University, using optical observation onboard the Defense Meteorological Satellite Program F16 satellite. This project attempts to answer the question: Can ionospheric response to Space Hurricane events be observed from GNSS and Ionosonde data? Through the detrended Vertical Total Electron Content (VTEC) keogram derived from GNSS measurements and the key parameters from Ionosonde data, the answer is yes. The Observatori de l'Ebre (OE) node of PITHIA-NRF gives strong support on Ionosonde data processing and analysis, as well as valuable discussion.

INGV Saioa Arquero Campuzano STorm-related Study of Ionospheric iRRegularities over southern Europe using digisondes and GNSS Data (STIRRED) Finished
Affiliation: University Complutense of Madrid (UCM), Instituto de Geociencias IGEO (CSIC-UCM)

Abstract: Understanding the complex dynamics in the upper atmosphere is very challenging. The study of the ionosphere irregularities during disturbed geomagnetic conditions can shed light on some of its characteristics. In last years, it was observed that several irregularities effects during geomagnetic storms were placed in southern Europe at 35º-40º geomagnetic latitudes. In this project, ionosphere effects of two moderate geomagnetic storms, 26–27 February 2014 and 17–18 September 2021, were studied over the Iberian Peninsula using different data sources. Data came from digital ionosondes in Spain, Italy and Greece; Global Navigation Satellite System (GNSS) derived Total Electron Content (TEC) and Rate Of TEC Index (ROTI) from several receiver stations in Spain, Portugal and Morocco; and UPC Quarter-of-an-hour time resolution Rapid GIM (UQRG), vertical TEC global ionosphere maps (GIMs) produced at 15 minutes intervals by the Universitat Politecnica de Catalunya (UPC, Spain). The main outcomes of this analysis showed that, during the two moderate storms, spread-F and high values of ROTI, indicating the presence of irregularities, were found in a very localized area (Southern Iberian Peninsula and northwest Africa) and local times (nighttime). Irregularities eastwards and northwards of that location were not found. Some possible explanations for these observations were proposed. The effects observed during the 26-27 February 2014 storm were related to the position of the Equatorial Ionosphere Anomaly (EIA). For the other one (17-18 September 2021 storm), they were attributed to the Perkins’ instabilities. Thanks to PITHIA-NRF project and the TNA program, skills to analyze ionograms with presence of irregularities such as spread-F were acquired, and it was provided access and training to use electronic Space Weather upper atmosphere (eSWua) web portal from Istituto Nazionale di Geofisica e Vulcanologia (INGV) to download the ionograms to detect the spread-F.

OE Andres Calabia Aibar Characterization of Plasma Depletions and Effects on Geodetic Applications Finished
Affiliation: School of Remote Sensing and Geomatics Engineering, Nanjing University Information Science Technology, Nanjing, China

Abstract: The variable space weather conditions can harvest detrimental impacts on satellite communications, Global Navigation Satellite Systems (GNSS), and countless other applications. These negative impacts emphasize the necessity to better understand and predict the upper atmosphere effects in the near-Earth environment, specifically, the propagation delay, bending, and interferences of radio signals in the ionosphere. This project aims to address this scientific problem through a better understanding of space weather phenomena and analyses to characterize ionospheric plasma depletions. In this work, local features of the ionosphere are identified, monitored, and characterized from ionosonde measurements at Ebro Observatory, satellite ultraviolet images from Special Sensor Ultraviolet Spectrographic Imager (SSUSI), total electron content (TEC) index (ROTI) from GNSS, and all-sky 630 nm images at Oukaïmeden Observatory. Several conclusions, questions, and conclusions are discussed, especially the dynamics and coupling processes of these depletions in relation to upper atmosphere and space weather conditions during the geomagnetic storm of 28 February 2014.

EISCAT Hervé Lamy Can PolaRISation Measurements of Auroral emissions Trace the Ionospheric Currents? In progress
Affiliation: Royal Belgian Institute for Space Aeronomy (BIRA-IASB)

Abstract: We have developed recently an imaging polarimeter called PLIP (Polar Lights Imaging Polarimeter) which is able to measure polarisation of the three main auroral emissions (green, red and blue) on a large FOV (~44° × 30°) on the sky. An observation campaign will be organized at the Skibotn Observatory in November 2022 on a 10 day period centred on the New Moon (23 November) to avoid strong contamination by Rayleigh-scattered moonlight. The goal is to search for a possible link between the AoLP of the auroral emission lines and the directions of field-aligned and/or ionospheric currents. To achieve this objective, we plan complementary blue line observations with the ALIS_4D optical network which will provide us a 2-D reconstruction of field-aligned electron fluxes. With this TNA proposal, we would like to obtain additional measurements with the UHF/VHF antenna of EISCAT in Tromso. The UHF antenna should be operated field-aligned to provide a reference point to validate the results obtained with inversion of ALIS_4D optical observations. The VHF antenna should be operated in tri-static mode in order to obtain an estimate of the direction of the ionospheric currents, which will then be compared to AoLP (Angle of Linear Polarisation) observations obtained with PLIP. If possible, we request also a secondary node to be able to use the VHF receiving mode of KAIRA from the SGO node.

DLR-SO Simon Mackovjak Contribution to feasibility study of data-driven Autonomous Service for Prediction of Ionospheric Scintillations (ASPIS) Finished
Affiliation: Department of Space Physics, Institute of Experimental Physics, Slovak Academy of Sciences

Abstract: The ionosphere is the most important atmospheric layer that affects the radio signal between space-based missions and ground-based stations. All the disturbances that occur in the ionosphere (sudden changes in ion and electron densities) affect the signal as they can rapidly modify the amplitude and phase of the radio waves. Such modifications are called ionospheric scintillations. They represent a high-risk effect for the signal from GNSS (Global Navigation Satellite System) which is used for high-precision calculation of position and time synchronization. The ASPIS (Autonomous Service for Prediction of Ionospheric Scintillations) activity is dedicated to wider study if it is feasible to develop a data-driven service that will use available solar, space weather, geomagnetic, ionospheric, thermospheric data for a particular location as an input and autonomously provide an assessment of ionospheric scintillation in a specific time ahead as an output. Thanks to the PITHIA-NRF TNA program and during the stay at DLR-SO Node in Neustrelitz (DE), important progress in this activity was obtained. In what follows, the project process and outcomes are discussed and the follow-up activities are proposed.

NOA Wojciech Jarmolowski Sensitivity of Ionospheric Disturbance detection by Swarm in time of strong Earthquakes in Aegean region (SIDSEA) Finished
Affiliation: University of Warmia and Mazury in Olsztyn

Abstract: The project describes the analysis of sensitivity of electron density (ED) measurements collected by Swarm satellites, and selected ionospheric parameters determined by Athens ionosonde to the seismicity in the Aegean region. The period selected for the analyses extends for two years: 2020-2021. The magnitudes of the earthquakes (EQs) in 2020-2021 reached 7.0, and this was the strongest seismic activity in this region in time of Swarm mission. Swarm ED and ionosonde time series are analyzed with the use of short-term Fourier transform (STFT) in order to selectively chose those signal parts, which are the most sensitive to external, seismically-driven disturbances. The correlation between the seismically-driven ionospheric disturbances detected by Swarm and the EQs in the Aegean region revealed as higher than the correlation of Swarm with geomagnetic index and solar radio flux. The selected signal parts of ionosonde-derived parameters are also much more correlated with the seismic activity than with F10.7 or Kp index. NOA has provided ionosonde data, and hosted the investigators in Athens for extensive discussion on the project.

TNA3 INGV Anna Morozova Assessment of the ionospheric scintillation over Portugal – ALERT In progress
Affiliation: University of Coimbra, Instituto de Astrofísica e Ciências do Espaço

Abstract: Until recently, it was widely accepted that scintillation events do not pose any significant danger to GNSS-based technologies at middle latitudes. However, the sensitivity of GNSS instruments and their abundance constantly grow resulting in a concern of GNSS-users about impacts of ionospheric scintillations on the quality of the GNSS signal in the middle latitudes. Some studies were performed to assess the recurrence and the amplitude of ionospheric irregularities at middle latitudes (Mrak et al., 2020,, still, no such studies were ever performed for Portugal. The occurrence of potential ionospheric scintillation affecting low elevation southward GNSS measurements from receivers in Southern Europe can be studied using the S4 and ROTI scintillation indices computed from permanent GNSS receivers located in Southern Europe, during geomagnetically quiet and active periods.

Unfortunately, there are not many data sets of scintillation indices (SI), such as S4 and ROTI, that cover the SW part of the Europe (Iberian Peninsula). The IA-UC team already has access to a significant amount of GNSS SI observations made between November 2014 and March 2019 at Lisbon airport in the frame of one of our previous projects SWAIR (ESA Small Artes, 2014-2022, see Barlyaeva et al., 2020). This data set generated by a GNSS receiver with the SCINDA software consists of the total electron content (TEC) and SI data, available both in the SCINDA and ASCII format (Morozova et al., 2022b). The TEC data were already analysed, verified, and used for several studies (Morozova et al., 2020, 2022a), but the SI data still need to be verified. Preliminary tests of the SCINDA SI (S4 and ROTI) series (Oliveira and Morozova, 2022) suggest that there are no significant flaws in the observational series, however the full data set still needs a detailed verification.

We contacted the INGV scintillation group that runs the eSWua database which includes scintillation data as well. We would like to validate our scintillation data and put them in the context of supporting the European capabilities of scintillation monitoring by providing access to this data set through eSWua. An open access to this data will be beneficial for the ionospheric community: the ionospheric scintillations in the SW part of the Europe are poorly studied because of the limited amount of the observational data.

We expect that work done during both the PITHIA-TNA project we propose and further collaboration projects with the INGV group will help to fill this knowledge gap and will be beneficial both for the Portuguese and Italian ionosphere communities and would increase the monitoring capabilities in the Mediterranean area.

OE Krishnendu Sekhar Paul Height-time-intensity (HTI) application and validation in TID and Es signatures on extended datasets In progress
Affiliation: Frederick Research Center

Abstract: The project addresses the application of Height-time-intensity (HTI) technique applied by Frederick University researchers to identify Travelling Ionospheric Disturbance and Intermediate Descending Layer sporadic E activity (within 100-160 km) on the extended ionogram dataset available at the Roquetes ionospheric station. The application of the HTI technique will be exploited to reveal the climatology of LSTID activity over Roquetes (2005-2022) and compared with HF-INT results over Roquetes available since 2014. This task will reveal the level of agreement between HTI and HF-INT for a significant number of TID events over Roquetes that will enable an assessment of the agreement between the two techniques which operate on a different principle (HTI on raw ionograms and HF-INT on auto-scaled characteristics). With respect to the application of the HTI on the sporadic E activity over Roquetes, this task will facilitate an investigation of a possible solar activity effect on Intermediate Descending Layers over Roquetes. This is the first time such an extended dataset will be exploited for such a study.