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Comments on “Enormously large tippers observed in southwest China: can realistic 3‑D EM modeling reproduce them?” by S. Xu et al. (2023)

Earth,Planets and Space - Thu, 01/23/2025 - 00:00

Fast GNSS spoofing detection based on LSTM-detect model

GPS Solutions - Thu, 01/23/2025 - 00:00

Abstract

Spoofing detection is an essential process in global navigation satellite system anti-spoofing. Signal quality monitoring (SQM) methods have been widely studied as simple and effective means to detect spoofing. However, the disadvantages of the existing SQM methods, such as long alarm times and low detection rates, necessitate the study of new methods. Therefore, to address these challenges, this paper proposes a novel SQM method based on a long short-term memory-detect (LSTM-Detect) model with a strong capacity for sequential signal processing. In particular, this method evaluates the distortion of the autocorrelation function (ACF) by the trained LSTM-Detect model for spoofing detection. The simulation results demonstrate that the LSTM-Detect model can detect a wide range of spoofing signals, varying in signal power advantages, code phase differences, and carrier phase differences. In the Texas Spoofing Test Battery datasets 2–6, the detection rate exceeds 98.5%, with an alarm time of less than 5 ms. Compared with five existing SQM methods, the LSTM-Detect model exhibits a more comprehensive spoofing detection performance.

Recent advances and applications of low-cost GNSS receivers: a review

GPS Solutions - Thu, 01/23/2025 - 00:00

Abstract

Low-cost (LC) Global Navigation Satellite System (GNSS) receivers are argued as an alternative solution to geodetic GNSS counterparts for different applications. Single-frequency low-cost (SF-LC) GNSS receivers have been in the market for many years while their inability to acquire GNSS observations in second frequency limited their use. A few years ago, dual-frequency low-cost (DF-LC) GNSS receivers with enhanced capabilities entered the mass market, considering the advancements they have been tested and evaluated by many researchers. Lastly, multi-frequency low-cost (MF-LC) GNSS receivers become available. With the ability to track more satellite signals, these GNSS receivers are expected to obtain better overall performance. This review article aims to analyze recent advances and applications of LC GNSS receivers. To provide answers to the research question relevant articles were selected and analyzed. From the reviewed articles, it was concluded that the performance of SF-LC and DF-LC GNSS receivers is comparable to that of geodetic counterparts only in open-sky conditions. However, in adverse conditions, the differences become more highlighted. In such environments, SF and DF-LC GNSS receivers face challenges not only with positioning quality but also with their proper work. Limited studies on MF-LC receivers have reported comparable observations and positioning performance to geodetic GNSS receivers. Despite drawbacks, LC GNSS receivers have been successfully applied in surveying, mapping, geodetic monitoring, precision agriculture, navigation, atmosphere monitoring, Earth surface monitoring, and other fields.

Coral bleaching and mortality overestimated in projections based on Degree Heating Months

Nature Geoscience - Thu, 01/23/2025 - 00:00

Nature Geoscience, Published online: 23 January 2025; doi:10.1038/s41561-024-01635-7

Coral bleaching and mortality are substantially overestimated in most model projections that are based on Degree Heating Months instead of Degree Heating Weeks, calling into question results generated using Degree Heating Months.

Long-lived partial melt beneath Cascade Range volcanoes

Nature Geoscience - Thu, 01/23/2025 - 00:00

Nature Geoscience, Published online: 23 January 2025; doi:10.1038/s41561-024-01630-y

Upper-crustal magma bodies are present beneath most Cascade Range volcanoes, indicating that large volumes of melt can persist at shallow depth through eruption cycles, according to systematic seismic imaging.

An efficient decoupled 3-D axial anisotropic resistivity inversion for magnetotelluric data with OpenMP parallelization

Earth,Planets and Space - Thu, 01/23/2025 - 00:00

We have developed two novel axial anisotropic inversion codes for magnetotelluric (MT) data: a full axial inversion and a decoupled axial inversion. Both codes are based on the data space Gauss–Newton inversio...