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The in situ and laboratory MSW biodegradation is a long-term process, thus the assessment of its performance can be arduous. A sand-salt mixture is often used to replace an MSW specimen for simplification or approximation, with dissolution representing biodegradation. However, the effectiveness of this approximation still needs to be confirmed, and the effects of the initial properties and test conditions such as unstable fraction, size ratio, initial compaction, and vertical stress on the accuracy of this approximation are unknown. In this study, supplementary dissolution tests of sand-salt mixtures are first conducted to construct a dataset for sand-salt mixtures and MSW specimens. Then, the settlement, one of the most important characteristics in practice, is chosen to be the indicator to compare the suitability of this approximation based on test groups with different unstable fractions, while the effects of other initial properties and conditions are also investigated. Overall, the effectiveness of the approximation largely depends on the biodegradable fraction and salt fraction, while other properties only pose limited effects. Nanyang Technological University Submitted/Accepted version The authors would like to acknowledge Nanyang Technological University (NTU, Singapore) and Interdisciplinary Graduate Programme (IGP) for the financial support and scholarships of this research.

GNSS data collected from thousands of stations are processed to generate global measurements of ionospheric irregularities. The measurements include the rate of TEC index (ROTI), small-scale TEC slopes (SSTS) and the spectrum of TEC variations at scales less than 50 km. These measurements are analyzed to investigate low-latitude ionospheric irregularities (LIIS) in different longitude sectors including Africa, America, Asia and Pacific during geomagnetic storms. A number of major storm events are selected to investigate the impact of space weather on the occurrence and intensity of LIIS in typical scintillation and non-scintillation seasons. Comparisons are made between LIIS and space weather measurements, including the interplanetary magnetic field, solar wind speed, derived magnetospheric electric field, and geomagnetic indices. The observations show that the variability of LIIS longitudinal patterns in triggering, enhancement and/or suppression are associated with the local time effects of ionospheric, thermospheric and magnetospheric dynamics in evening, post-midnight and dawn-time hours. This paper will present the methods of GNSS-based ionospheric irregularity measurements, distinguished LIIS activities in different longitude sectors, their associations with space weather perturbations, and the implication of underline global dynamical perturbations during the storms., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Ionospheric propagation effects can have significant impact on the signal properties of low-frequency Synthetic Aperture Radar (SAR) systems. Recently, theoretical analyses of ionospheric distortions in low-frequency SAR signals have indicated a multitude of effects that are likely to affect the quality of SAR, interferometric SAR (InSAR), and polarimetric SAR (PolSAR) data [1-6]. Methods have been developed that are able to detect ionospheric effects in SAR data on a wide range of spatial scales and allow high resolution ionospheric mapping with high accuracy [3], [4], [7]. NASA’s Deformation, Ecosystem Structure and Dynamics of Ice (DESDynI) mission carries a spaceborne L-band synthetic aperture radar (SAR) with multiple polarizations to provide information on solid earth deformation, terrestrial vegetation structure, and ice dynamics. Besides providing improved performance and reliability of SAR for monitoring surface deformation, the L-band carrier frequency provides a means for mapping properties of the ionosphere with high spatial resolution and unprecedented spatial coverage. This paper describes the performance and benefits of DESDynI for ionospheric mapping. Specifically, we quantify the type, sensitivity, and accuracy of ionospheric measurements derived by a DESDynI-like system. We also analyze the achievable spatial and temporal sampling of ionospheric constituents at different areas on the globe and assess the value of the derived information for specific ionospheric research topics. After summarizing the physical origin of ionospheric signals in SAR data, Section 2 introduces several methods for extracting ionospheric information from DESDynI data. For each method, information on the measurement principle is provided and the range of extractable ionospheric parameters is determined. A first concept for an optimized ionospheric processor is shown that extends the performance of existing technology by maximizing the exploited information and increasing estimation robustness. An error analysis of the presented technology is shown in Section 3, where achievable accuracies of ionospheric measurements are analyzed for different retrieval methods. In Section 4 the benefit of SAR-based ionospheric data for ionospheric research is evaluated. In examples we examine its value for analyzing turbulent ionospheric processes in polar and equatorial regions, and for evaluating the structure of traveling ionospheric disturbances (TIDs) at various spatial scales.