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Inland water bodies are essential sources of freshwater for several applications, making their level monitoring crucial for understanding the impact of climate change and human activities. The Global Ecosystem Dynamics Investigation (GEDI) [1,2] mission utilizes a spaceborne LiDAR altimeter to produce high-resolution measurements of Earth's canopy. GEDI has recently been added in Google Earth Engine (GEE), a cloud-based platform integrating different datasets and providing efficient analysis tools. This study aims to evaluate the accuracy of GEDI altimetric data over water bodies, comparing the levels recorded by GEDI with ground truth measurements. Furthermore, a robust procedure to remove outliers is proposed and implemented within GEE. Specifically, a number of lakes all over Italy were selected and analyzed for the period from April 2019 to June 2022. The proposed outlier detection methodology consists of two stages. The first employs two flags provided by GEDI metadata. The "quality_flag" and "degrade_flag" provide information about the footprint validity, based respectively on GEDI signal anomalies and the degradation state of pointing or positioning information. Secondly, the methodology employs a robust implementation of the standard 3σ-test, utilizing the Normalized Median Absolute Deviation (NMAD) to identify outliers: measurements not within the range of -/+3*NMAD from the median are removed. After the outlier removal, we obtain an average NMAD of 0.11m over the ten lakes for the considered period.[1] Dubayah et al., 2021. GEDI L3 gridded land surface metrics.[2] University of Maryland, 2022. GEDI ecosystem lidar. www.gedi.umd.edu., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

The ability to issue timely tsunami warnings is a key challenge in GNSS Ionospheric Seismology research.In this context, Total Electron Content (TEC) estimates represent an important parameter to sound the ionosphere using Global Navigation Satellite Systems (GNSS) observations. Earthquakes and tsunamis are, indeed, known to generate acoustic and gravity waves (AGWs), able to reach the ionosphere and cause perturbations in TEC values, known as Travelling Ionospheric Disturbances (TIDs). In this study, we use the VARION algorithm, able to estimate TEC variations in real time, to investigate the eventual TIDs connected to Mw 7.0 Samos earthquake (37.8360° N 26.8080° E) that occurred on 30 October 2020. We employ 10 GNSS receivers from the Turkish and Greek networks (respectively TUSAGA-Akitf and HEPOS). We consider both raw and filtered VTEC variations. Specifically, we adopt bandpass and polynomial filters. We highlight small TEC variations possibly linked to the passage of acoustic-gravity waves. Spectral analysis shows peak frequency around 1-2 mHz. The challenge of this study is, indeed, to eventually retrieve and highlight small amplitude TEC variations connected to the earthquake and tsunami. To this aim, we also use tide gauges (IOC_UNESCO) data to retrieve information on the tsunami waves.In conclusion, the obtained results emphasize the importance of using GNSS ionospheric data to study and complete other known methods used for tsunami hazard estimation in the Mediterranean Sea., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Collection of four presentations related to GNSS training at the 1st GATHERS Summer School. Content of following presentations: GATHERS-T.5.1.1-Summer-School-GNSS-Seismology-Crespi-PU.pdf - demonstrates the introduction to GNSS measurements theory, basic geometric and microwave properties of the signal, reference frames definition GATHERS-T.5.1.1-Summer-School-GNSS-PPP-Kaplon-PU.pdf - introduce the concept of Precise Point Positioning, international GNSS service products to support real-time processing,strengths and limitations, GATHERS-T.5.1.1-Summer-School_GNSS-VADASE-Crespi-PU.pdf - is introducing the variometric method to estimate displacements and list number of applications GATHERS-T.5.1.1-Summer-School-GNSS-instructions-Kaplon-PU.pdf - that is discussing the processing and filtration strategies aiming at the detecting and estimating the seismic signals in GNSS displacement time-series &nbsp