Feed aggregator

Nature Geoscience, Published online: 11 February 2025; doi:10.1038/s41561-024-01633-9

Rhabdophane contains high concentrations of the rare earth elements, yet Tobias Bamforth argues that it remains underappreciated as a significant host of these critical metals.

Nature Geoscience, Published online: 11 February 2025; doi:10.1038/s41561-025-01651-1

Sustained monitoring is essential for assessing volcanic hazards. Integration with igneous petrology is key to linking monitoring data to underlying magmatic processes.

The triggering mechanism of the substorm onset has been a major issue in magnetospheric research. Various models have been proposed so far. To understand the causal relationship of magnetotail processes associ...

Abstract

The geodetic community commonly challenges the composite hypotheses in the statistical testing of mathematical models. Since the composite hypotheses are not specified as opposed to their simple counterparts, they require a prior estimation of the model parameters. However, if the mathematical models are ill-conditioned, the regularized estimation is often applied for the parameters of interest. Due to the biased property, the regularized estimation does not rigorously originate in the principle of maximum likelihood (ML) estimation, which was the base for developing the theory of the generalized likelihood ratio (GLR) test. Since the regularized estimator of the parameters of interest is consequently inconsistent with the ML one, one cannot construct the GLR test, which is the uniformly most powerful invariant (UMPI) test. So far, only the bias correction approach has been suggested to solve this problem. In this contribution, an implicit representation of the regularized mathematical model is proposed. It eliminates the complete impact of regularized estimation on a mathematical model and delivers the misclosures analytically free from the influence of regularization. Thus, one can construct the GLR test, which belongs to the UMPI family, and then formulate the test statistic in terms of misclosures.

Abstract

This short article highlights unsolved problems of magnetic reconnection in collisionless plasma. Advanced in-situ plasma measurements and simulations have enabled scientists to gain a novel understanding of magnetic reconnection. Nevertheless, outstanding questions remain concerning the complex dynamics and structures in the diffusion region, cross-scale and regional couplings, the onset of magnetic reconnection, and the details of particle energization. We discuss future directions for magnetic reconnection research, including new observations, new simulations, and interdisciplinary approaches.

Nature Geoscience, Published online: 10 February 2025; doi:10.1038/s41561-025-01647-x

The rigid-body motion of Earth’s wandering inner core has now been reliably tracked over the past 20 years. With this knowledge, we can compare seismic recordings obtained when the inner core returns to the same position after moving for several years. More is changing than just the inner core position; the soft outermost inner core probably deforms.

Nature Geoscience, Published online: 10 February 2025; doi:10.1038/s41561-025-01642-2

Earth’s inner core has both changed its relative rotation rate and deformed in the past few decades, according to an analysis of seismic waves recorded when the inner core occupied the same relative location owing to its changing rotation rate.

Abstract

The seismo-electromagnetic studies have been in progress since 1998 at Agra station. In the present paper, ionospheric GPS-TEC, ground-based ULF/VLF measurements were investigated in light of four strong earthquakes (M ≥ 6.8) that occurred around the Indian subcontinent in different periods. These three datasets are processed by using advanced signal-processing techniques in time and frequency domains. To analyze these datasets, a period of 16 days (including the day of the earthquake) was considered. For each day, only one minute of data was taken into account, with the time of the earthquake being the midpoint of that minute. The precursors are obtained in all the datasets considered before the occurrence of earthquakes. In TEC, ULF, and VLF data, significant changes are observed 2 to 15, 2 to 7, and 5 to 13 days before earthquakes, respectively. Significant results are obtained in time and frequency domains and the variations of solar and magnetic storm activities have also been examined thoroughly to check the validity of these variations. Further, these variations are interpreted in terms of lithosphere-atmosphere-ionosphere coupling mechanisms available in the literature.

Abstract

This study investigates Pc5 pulsations during the St. Patrick’s Day geomagnetic storm of March 17, 2015, using ground-based magnetic data from the SER station in Chile (29.827° S, 71.261° W), satellite observations, and geomagnetic indices. Pc5 pulsations, with frequencies of 1.67–6.67 mHz, are influenced by various factors, including the Kelvin–Helmholtz instability, field line resonance effects, and solar wind dynamics. During this storm ignificant variations in solar wind parameters were observed, with positive correlations between Pc5 pulsations and parameters like temperature, density, speed, and pressure, especially during the main and recovery phases Pc5 pulsations exhibited large amplitudes during the storm, potentially driven by magnetospheric MHD waveguide/cavity mode and induced by the substantial compression of the geomagnetic field from the solar wind. Our results show the appearance of Pc5 pulsations at low latitudes and strong correlations between solar wind parameters and Pc5 signals during all storm phases, with maximum correlation coefficients of 0.98.

Abstract

The occurrence of geomagnetic storms and the variation in the geomagnetic storm indices during the ascending phase of solar cycle 24 has been examined. The parameters considered for this study includes; IMF Bz (nT), solar wind speed ( \({{{v}}_{x}}\) , in km/s), Dst index (nT), Aurora Electroject (AE, AU and AL indices in nT), and sunspot number. The datasets span from 2010 to 2012. Results of the study reveals that; the frequency of occurrence of geomagnetic storms increases with the increase in solar activity. Six (6) geomagnetic storms were recorded in 2010 (with sunspot number, Rz = 16.5), 13 storms in 2012 (with sunspot number Rz = 55.7), and 17 storms occurred in 2012 (with sunspot number, Rz = 57.5) giving a total of 36 geomagnetic storm events for the entire period. The performed study demonstrates that an increase in the speed and density of the solar wind coincided with the decrease in the Dst index in 58% cases (in 21 out of 36 geomagnetic storms). However, in some cases, there was a sharp simultaneous increase in both the speed and density of the solar wind that fell on the recovery phase of the storm. This also in most cases coincided with the sharp north-south fluctuations in the IMF Bz. These variations cannot be unconnected with the nature of the drivers of such geomagnetic storms. It is evident that the behavior of the solar wind speed during geomagnetic storm events can provide meaningful insight on the underlying mechanisms and processes that drive the geomagnetic storm.

Nature Geoscience, Published online: 10 February 2025; doi:10.1038/s41561-024-01629-5

Diverse lithospheric rocks show nanoporosity that changes the geochemistry of fluids and rock reactivity during fluid–rock interactions, according to a study including electron microscopy, molecular dynamics and thermodynamic modelling.

Nature Geoscience, Published online: 10 February 2025; doi:10.1038/s41561-025-01649-9

Ocean pH probably rose rapidly in the Hadean and early Archaean due to elevated rates of seafloor and continental weathering, according to a model integrating global carbon cycling and ocean geochemistry with continental growth and mantle thermal evolution.

Abstract

Magnetic reconnection is a ubiquitous plasma process that transforms magnetic energy into particle energy during eruptive events throughout the universe. Reconnection not only converts energy during solar flares and geomagnetic substorms that drive space weather near Earth, but it may also play critical roles in the high energy emissions from the magnetospheres of neutron stars and black holes. In this review article, we focus on collisionless plasmas that are most relevant to reconnection in many space and astrophysical plasmas. Guided by first-principles kinetic simulations and spaceborne in-situ observations, we highlight the most recent progress in understanding this fundamental plasma process. We start by discussing the non-ideal electric field in the generalized Ohm’s law that breaks the frozen-in flux condition in ideal magnetohydrodynamics and allows magnetic reconnection to occur. We point out that this same reconnection electric field also plays an important role in sustaining the current and pressure in the current sheet and then discuss the determination of its magnitude (i.e., the reconnection rate), based on force balance and energy conservation. This approach to determining the reconnection rate is applied to kinetic current sheets with a wide variety of magnetic geometries, parameters, and background conditions. We also briefly review the key diagnostics and modeling of energy conversion around the reconnection diffusion region, seeking insights from recently developed theories. Finally, future prospects and open questions are discussed.

Abstract

A 6-year cycle has long been recognized to influence the Earth’s rotation, the internal magnetic field and motions in the fluid Earth’s core. Recent observations have revealed that a 6-year cycle also affects the angular momentum of the atmosphere and several climatic parameters, including global mean sea level rise, precipitation, land hydrology, Arctic surface temperature, ocean heat content and natural climate modes. In this review, we first present observational evidences supporting the existence of a 6-year cycle in the Earth system, from its deep interior to the climate system. We then explore potential links between the Earth’s core, mantle and atmosphere that might explain the observations, and investigate various mechanisms that could drive the observed 6-year oscillation throughout the whole Earth system.

Abstract

As a critical parameter in meteorological monitoring, precipitable water vapor (PWV) is widely used in short-term extreme weather forecasting and long-term climate change research. However, as PWV exhibits significant vertical attenuation, especially within 2 km, achieving accurate vertical interpolation is essential for comparisons and fusion across different measurement techniques, such as sampling water vapor at different heights. PWV vertical adjustment relies only on the empirical or time-varying lapse rate models (e.g., GPWV-H). The non-uniform vertical distribution of PWV and the uncertain variation trend in the low-latitude region still limit the accuracy. To address these issues, we propose the Spatially enhanced Vertical Adjustment Model for PWV (SPWV-H), taking into account the non-uniform distribution in the vertical direction based on the fifth-generation European Centre for Medium-Range Weather Forecasts Atmospheric Reanalysis (ERA5) products. The assessment, validated against the ERA5 benchmark, highlights the SPWV-H model’s superior performance with an RMSE of 1 mm and a bias of 0.03 mm, especially pronounced in the low-latitude region. Compared to global radiosonde datasets, the SPWV-H model achieves notable reductions in RMSE of 12%, 11%, and 18% when evaluated against the EPWV-H, GPWV-H, and GPT3-1 models, respectively. In spatial interpolation, the SPWV-H model achieves an RMSE of 1.22 mm, indicating an improvement of 10%, 9%, and 14% compared to the EPWV-H, GPWV-H, and GPT3-1 models, respectively. Therefore, the SPWV-H model can provide a reliable service for multi-source PWV fusion and real-time PWV monitoring by GNSS.

Abstract

In February 2023, the International Laser Ranging Service started the tracking of additional medium Earth orbit satellites from the global BeiDou navigation satellite system (BDS) constellation, increasing the total number of tracked BDS satellites to 27. As an optical space geodesy technique, the Satellite Laser Ranging (SLR) provides another important measurement for BDS other than the microwave (L-band) one. Based on three years of data from June 2021 to May 2024, the potential benefits of introducing SLR data into BDS processing and analysis are investigated from three key aspects: orbit validation, precise orbit determination, and geodetic parameters estimation. The independent SLR validations of BDS precise orbit products from four analysis centers show that using the a priori box-wing model for solar radiation pressure (SRP) modeling can achieve superior performance than purely empirical models. The results also indicate the existence of SRP modeling deficiencies for some satellites such as C45 and C46 with Search and Rescue payloads. Given a sparse ground network with 5 stations, the introduction of SLR significantly stabilizes the SRP parameter estimates and improves the orbit accuracy by 44.4%. In terms of geodetic parameter estimation, the scatter of the Z-component geocenter motion can be effectively reduced with the inclusion of SLR data, presenting 10.9–15.3% smaller root mean square (RMS) values during February 2023 and May 2024, depending on the SRP models. In addition, the annual amplitudes of the Z-component geocenter motion are reduced by 7.2–48.2%. The improvement is more pronounced with a limited number of microwave stations, due to the greater strength of SLR observations in geocenter motion estimation. On the other hand, since the SLR observations are unhomogeneously distributed in both space and time, the incorporation of SLR does not evidently enhance the accuracy of Earth rotation parameters, and may even to some extent contaminate the results when the number of microwave stations is limited.

Abstract

Traditional ionospheric modeling is inseparable from dense Global Navigation Satellite System (GNSS) reference stations. In this study, based on definite linear variation characteristics of the ionosphere along the longitudinal and latitudinal directions, a regional ionospheric total electron content (TEC) fusion model was proposed using relatively sparse GNSS linear stations beyond 100 km. Compared with the inverse distance weighting model using two adjacent stations with 100 km distance and three surrounding stations with 30 km distance, the accuracy of the proposed model has an improvement by 39.6% and 55.6% respectively, reaching a root-mean-square error of 0.32 TECU (TEC Unit) at mid-latitudes in high solar activity year. In the low solar activity year, the accuracy of the proposed model also achieves a high accuracy of 0.24 TECU at mid-latitudes and 0.86 TECU at low-latitudes. Finally, the proposed model was verified by precise point positioning (PPP). Compared with the traditional PPP, the ionosphere model enhanced PPP can significantly shorten the convergence time from 22.1 to 10.3 min in the magnetic storm period, and from 23.2 to 8.8 min in the quiet period.

Abstract

The SMILE ground segment comprises the Chinese Academy of Sciences (CAS) ground segment and the European Space Agency (ESA) ground segment, which collaborate closely on this mission. The Ground Support System (GSS) and the Science and Application System (SAS) are two important components of the CAS ground segment. Development of these systems began in 2016, focusing on requirements for addressing the significant challenges associated with the SMILE mission. The GSS is primarily responsible for data reception, mission operations, data processing, data management, and data services. It has established an operational platform based on a “common platform + mission-specific plug-ins” model, enabling support for the SMILE mission through the development of tailored plugins. The SAS functions as a dedicated scientific research center for the SMILE mission within CAS, managing science operations, processing scientific data, and conducting scientific data analysis. Its establishment was driven by the unique requirements of the SMILE mission. Additionally, the SAS is tasked with fostering collaboration between CAS and ESA, designing effective frameworks to coordinate scientists in planning SMILE science operations. This paper provides a brief overview of the design of the GSS and SAS, as well as SMILE mission operations. We anticipate that these two systems will effectively support the SMILE mission in the future.

Abstract

NASA’s Europa Clipper mission is the first focused exploration of an ocean world, with the main goal of assessing the habitability of Jupiter’s moon Europa. After entering Jupiter orbit in 2030, the Flight System (spacecraft plus instrument payload) will collect science data while flying past Europa a planned 49 times at typical closest approach distances of 25–100 km. The mission will investigate Europa’s interior, composition, and geology, and will search for and characterize any current activity including possible plumes. The mission’s science objectives will be accomplished with a payload component of the Flight System that includes both remote sensing instruments covering the ultraviolet, visible, infrared, and thermal infrared ranges of the electromagnetic spectrum, as well as an ice-penetrating radar, and in situ instruments, that will be used to study the magnetic field, dust, gas, and plasma surrounding Europa. The spacecraft component of the Flight System is designed to permit all science instruments to operate and gather science data simultaneously. This paper will outline the driving requirements for the overall spacecraft as well as describe the resulting spacecraft design and its key characteristics, including an overview of flight system-level integration and testing.

Nature Geoscience, Published online: 05 February 2025; doi:10.1038/s41561-025-01639-x

Uptake of explainable artificial intelligence (XAI) methods in geoscience is currently limited. We argue that such methods that reveal the decision processes of AI models can foster trust in their results and facilitate the broader adoption of AI.