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Abstract

Determining the mechanisms responsible for intraplate volcanism - such as slab devolatilization melting versus active mantle plumes - remains a challenge. The greater South China Sea (SCS) region has experienced extensive intraplate Cenozoic volcanism across areas including Hainan, Southeast Indochina, northern Borneo, the northern SCS, and the post-spreading SCS basin. The prevalence of volcanism distributed widely across this region prompts fundamental questions about the key geodynamic processes driving such diverse magmatic activities. In this study, we elucidate the mantle transition zone (MTZ) discontinuities in this region using SS precursors, which helps to overcome the sparse seismic coverage due to its predominantly oceanic setting. We collected over 16,000 high-quality seismograms that sample the upper mantle and MTZ beneath this region from global earthquakes and stations. After correcting for the effects of shallow crustal variations and upper mantle heterogeneity on traveltimes of SS phases and their precursors, we unveil lateral variations in the MTZ boundaries (d410 and d660) and intricate features of the mid-MTZ reflectors (S520S). Significant MTZ thinning and normal S520S waveforms beneath Hainan provide compelling evidence for mantle upwelling through the MTZ. Conversely, the evident splitting of S520S beneath the northern SCS, Southeast Indochina, and northern Borneo, all characterized by stagnant subducted slabs, indicates that the volcanism in these regions likely originated from a mechanism distinct from the active upwelling beneath Hainan. Dehydration melting attributed to devolatilizing stagnant slabs in the MTZ is a potential cause for Cenozoic volcanism in these regions.

Author(s): Zhengfeng Fan, Chengxin Yu, Cong-Zhang Gao, Xuefeng Xu, Cunbo Zhang, Binbing Wu, Jie Liu, Pei Wang, and Shaoping Zhu

Modeling the nonequilibrium process between ions and electrons is of great importance in laboratory fusion ignition, laser-plasma interaction, and astrophysics. For hot and dense plasmas, theoretical descriptions of Coulomb collisions remain complicated due to quantum effect at short distances and s…

[Phys. Rev. E 110, 025202] Published Tue Aug 06, 2024

Author(s): Jaemin Seo

Reconstructing the past of observed fluids has been known as an ill-posed problem due to both numerical and physical challenges, especially when observations are distorted by inevitable noise, resolution limits, or unknown factors. When employing traditional differencing schemes to reconstruct the p…

[Phys. Rev. E 110, 025302] Published Tue Aug 06, 2024

Abstract

Utilizing multistatic specular meteor radar (MSMR) observations, this study delves into global aspects of wind perturbations in the mesosphere and lower thermosphere (MLT) from the unprecedented 2022 eruption of the Hunga Tonga-Hunga Ha'apai (HTHH) submarine volcano. The combination of MSMR observations from different viewing angles over South America and Europe, and the decomposition of the horizontal wind in components along and transversal to the HTHH eruption's epicenter direction allow an unambiguous detection and identification of MLT perturbations related to the eruption. The performance of this decomposition is evaluated using Whole Atmosphere Community Climate Model with thermosphere/ionosphere extension (WACCM-X) simulations of the event. The approach shows that indeed the HTHH eruption signals are clearly identified, and other signals can be easily discarded. The winds in this decomposition display dominant Eastward soliton-like perturbations observed as far as 25,000 km from HTHH, and propagating at 242 m/s. A weaker perturbation observed only over Europe propagates faster (but slower than 300 m/s) in the Westward direction. These results suggest that we might be observing the so-called Pekeris mode, also consistent with the L 1 pseudomode, reproduced by WACCM-X simulations at MLT altitudes. They also rule out the previous hypothesis connecting the observations in South America to the Tsunami associated with the eruption because these perturbations are observed over Europe as well. Despite the progress, the L 0 pseudomode in the MLT reproduced by WACCM-X remains elusive to observations.

Abstract

Low Earth Orbit (LEO) satellites can augment the traditional GNSS-based positioning, navigation and timing services, which require real-time high-precision LEO satellite clock products. As the complicated systematic effects contained in the LEO satellite clock estimates limit their high-precision mid- to long-term prediction, high-frequency LEO satellite clocks need to be estimated within a Kalman filter, resulting in a short prediction time for real-time applications. Compared to the clock estimation using Batch Least-Squares (BLS) adjustment, filter-based clock estimation experiences a lower precision. Increasing the model strength by introducing external orbital information, thus, de-correlating the orbital and clock parameters, will benefit real-time clock precision. In this contribution, reduced-dynamic LEO satellite orbits are first estimated using BLS adjustment in near real-time and predicted in the short term. The predicted orbits are then constrained during the Kalman-filter-based clock estimation process. The variance–covariance matrix of the introduced orbital errors is tested for different sets of values in the radial, along-track and cross-track directions when constraining orbits of different prediction times. One week of GPS data from the Sentinel-3B satellite in 2018 was used for validation of the proposed method. When weakly constraining high-accuracy predicted orbits within a prediction time of 20 min, i.e., with a standard deviation of the constraint set to 2–3 dm in the radial and cross-track directions, and 4–6 dm in the along-track direction, the estimated clock accuracy can be improved from about 0.27 to 0.23 ns, with a 13.4% improvement. Depending on the prediction period of the introduced orbits, the Signal-In-Space Range Error (SISRE) of the LEO satellite to Earth can also be improved, from about 9.59 cm without constraints, to 7.38–8.07 cm after constraining the predicted orbits, with an improvement of 16–23%. The improvements in the SISRE also indicate a better consistency between the real-time clock and orbital estimates.

Understanding flow behavior in a geothermal reservoir is important for managing sustainable geothermal energy extraction. Fluid flow in geothermal reservoirs generally occurs in complex existing fracture syste...

Abstract

The radio navigation satellite system (RNSS) timing has been widely used in crucial power systems. However, the problem of RNSS service vulnerability to interference and spoofing significantly affects its application. The phasor measurement unit can effectively detect timing spoofing that exceeds the maximum allowable error, but there has been less research on small-offset timing spoofing. We propose a joint timing spoofing detection method of the radio determination satellite system (RDSS) and RNSS in BDS for small-offset timing spoofing. The RDSS service uses an authentication mechanism in the master station, making it challenging to be spoofed, and it has the same time and space references as the RNSS service. We obtain the RNSS and RDSS timing signal counts and performs dynamic time wrapping to measure the similarity metric of two-time series as a detection quantity. Then, the proposed method is verified by actual experiments. The experiment results show that the detection probability of the RDSS-assisted method is significantly higher than that of the method only using the RNSS variance. The detection probability of the proposed method can reach 90% at a false alarm probability of 0.1, which verifies the accuracy and reliability of the proposed method.

Nature Geoscience, Published online: 06 August 2024; doi:10.1038/s41561-024-01502-5

Tracking biodiversity potential is time-sensitive under climate change, especially in the most remote areas. A new analysis fulfils a long-standing need to map the terrestrial vegetation across Antarctica — a crucial step to identify carbon and nutrient cycling hotspots.

Nature Geoscience, Published online: 06 August 2024; doi:10.1038/s41561-024-01486-2

Computational simulations of Venus’s geodynamics show the formation of large tessera plateaus. Matching of the models with spacecraft orbiter data constrains the mechanism that may have formed the topography of Ishtar Terra and other plateaus on Venus, suggesting that these features might have formed by a mechanism similar to that of the early continents on Earth.

Nature Geoscience, Published online: 06 August 2024; doi:10.1038/s41561-024-01492-4

Satellite-based mapping of vegetation shows that photosynthetic life occupies a total area of 44.2 km2 across Antarctica.

Abstract

Accurate surface longwave downward radiation (SLDR) is crucial for understanding mountain climate dynamics. While existing algorithms notably improve the accuracy of clear-sky SLDR, a terrain correction algorithm that can correct remotely sensed and model-simulated all-sky SLDR on a large scale remains largely unexplored. Here, we propose a parameterization scheme for estimating all-sky SLDR in rugged terrain. We primarily improve the estimation of nearby terrain thermal contribution by considering topographic asymmetry and incorporate the effects of ice cloud thermal scattering under low water vapor conditions. We validate the reliability of our model using the Discrete Anisotropic Radiative Transfer (DART) model, demonstrating a good agreement with a bias value of −12.8 W/m2 and a RMSE value of 28.2 W/m2. Further evaluation against the Essential Thermal Infrared Remote Sensing (ELITE) SLDR product at three TIPEX-III in situ sites, located near the bottom of deep valleys with predominantly flat surfaces, indicates significant improvement in our model, reducing the mean bias by 7.4 W/m2 and the mean RMSE by 4.1 W/m2. Post-terrain correction, the ELITE SLDR difference map exhibits a spatial pattern of “small in the northwest and large in the southeast” in the study area, with the maximum differences reaching 67 W/m2 in the daytime and 54 W/m2 at nighttime. Comparison with existing methods reveals similar improvements due to the consideration of terrain effects. Overall, our SLDR correction model shows enormous potential for correcting remotely sensed and model-simulated SLDR products on a large scale.

Boundary layer height variations under sunny, rainy, and cloudy weather conditions.

Abstract

The coastal boundary layer height (CBLH/Coastal-BLH) is critical in determining the exchange of heat, momentum, and materials between the land and ocean, thereby regulating the local climate and weather change. However, due to the complexity of geographical characteristics and meteorological conditions, accurate estimation of the CBLH remains challenging. Herein, based on continuous high-resolution measurements of CBL performed from November 2019 to April 2020 in coastal Ningbo city in eastern China, an optimal weighted ensemble model (OWEM) integrating multi-meteorological variables of the ERA5 reanalysis data sets is constructed and validated to estimate the CBLH. The mean absolute percentage error of the derived CBLH by OWEM is as low as 3%–5%, significantly lower than that of 36%–65% of the ERA5 CBLH products. Furthermore, three categories of different weather scenarios, that is, sunny, cloudy, and rainy, are separately discussed, and OWEM shows greater performance and higher accuracies in comparison with the traditional Least Absolute Shrinkage and Selection Operator, Random Forest, Adaboost, LightGBM, and ensemble model, among which, OWEM under fair weather days behave best, with a robust R 2 of 0.97 and a minimum mean absolute error (MAE) of 23 m. Further training results based on wind flow classification, that is, land breeze, sea breeze, and parallel wind, also indicate the outperformance of OWEM than other models, with a relatively large error in parallel wind of 50 m. Subsequent analysis of the Shapley Additive Explanations method strongly correlated with model feature importance, both reveal that thermodynamic factors such as temperature (T2m) and wind velocity (10 m U) are the major factors positively related to estimation accuracy during sunny days. Nevertheless, Relative Humidity dominates on rainy and cloudy days, TP on land breeze days, and dynamic variables like 10 m U and 10 m V on entire types of wind flow weather. In conclusion, the accurate estimation of CBLH from OWEM serves as a feasible and innovative approach, providing technical support for marine meteorology and related engineering applications, for example, onshore wind power, coastal ecological protection, etc.

A team of scientists and engineers at NASA and the U.S. Geological Survey (USGS) has collaborated to see if a small piloted drone, equipped with a specialized payload, could help create detailed maps of how fast water is flowing. Rivers supply fresh water to our communities and farms, provide homes for a variety of creatures, transport people and goods, and generate electricity.

Abstract

The impacts of falling ice radiative effects (FIREs) on land-atmosphere feedback processes were examined, with a focus on the fidelity of land surface properties and their variability as inferred by global climate models (GCMs). We conducted a pair of sensitivity experiments using the National Center for Atmospheric Research (NCAR) Community Earth System Model Version 1 (CESM1) in fully coupled modes with FIREs turned on and off. This allowed us to investigate the seasonal response of land surface properties to changes in radiation fluxes and land surface temperature (LST) associated with FIREs across global land areas. Our findings indicate that during boreal winter, excluding FIREs results in less surface downward longwave and net flux (∼5–15 Wm−2), leading to a colder land surface (∼2–4 K) and air temperatures (∼1–4 K) at mid- and high latitudes. Consequently, the surface frozen soil layer and snow cover persist through spring, delaying snowmelt and thawing until summer. This delay reduces liquid soil moisture, thereby suppressing vegetation productivity in subsequent seasons. Conversely, tropical regions, exhibit contrasting responses, with a warmer land surface (∼0.5 K) and warmer air temperatures (∼0.1–0.5 K) due to increased surface downward shortwave and net flux (∼2–10 Wm−2). This enhancement in radiation fosters increased vegetation productivity throughout the seasonal cycle. These findings illustrate a local response of land surface properties to changes in the surface energy balance and LST, highlighting the significant role that FIREs play in land surface modeling within GCMs.

The story of Greenland keeps getting greener—and scarier. A new study provides the first direct evidence that the center—not just the edges—of Greenland's ice sheet melted away in the recent geological past and the now-ice-covered island was then home to a green, tundra landscape.

Cloud phase estimation and macrophysical properties of low-level clouds using in-situ and radar measurements over the Southern Ocean during the SOCRATES campaign
Anik Das, Baike Xi, Xiaojian Zheng, and Xiquan Dong
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-124,2024
Preprint under review for AMT (discussion: open, 0 comments)
Understanding the cloud phase and macrophysical properties of Southern Ocean clouds is crucial to enhancing our understanding of the region. The cloud radar and in-situ probes during the SOCRATES aircraft campaign are used to develop a new method to determine cloud boundaries and dominant phase. Low clouds (<3km) are found to be the most dominant cloud type (~90%), with liquid being the most dominant phase type, followed by ice and mixed with a greater incidence of drizzle around the cloud base.

The formation of Earth's continents billions of years ago set the stage for life to thrive. But scientists disagree over how those land masses formed and if it was through geological processes we still see today.

Cloud masks and cloud type classification using EarthCARE CPR and ATLID
Hajime Okamoto, Kaori Sato, Tomoaki Nishizawa, Yoshitaka Jin, Shota Ogawa, Hiroshi Ishimoto, Yuichiro Hagihara, EIji Oikawa, Maki Kikuchi, Masaki Satoh, and Wooosub Roh
Atmos. Meas. Tech. Discuss., https://doi.org/10.5194/amt-2024-103,2024
Preprint under review for AMT (discussion: open, 0 comments)
The article gives the descriptions of the Japan Aerospace Exploration Agency (JAXA) level 2 (L2) cloud mask and cloud particle type algorithms for CPR and ATLID onboard Earth Clouds, Aerosols and Radiation Explorer (EarthCARE) satellite. The 355nm-multiple scattering polarization lidar was used to develop ATLID algorithm. Evaluations show the agreements for CPR-only, ATLID-only and CPR-ATLID synergy algorithms to be about 80%, 85% and 80%, respectively on average for about two EarthCARE orbits.

Abstract

The East African Rift System (EARS) provides an opportunity to constrain the relationship between magmatism and plate thinning. During continental rifting, magmatism is often considered a derivative of strain accommodation—as the continental plate thins, decompression melting of the upper mantle occurs. The Turkana Depression preserves among the most extensive Cenozoic magmatic record in the rift. This magmatic record, which comprises distinct basaltic pulses followed by periods of relative magmatic quiescence, is perplexing given the lack of evidence for temporal heterogeneity in the thermo-chemical state of the upper mantle, the nonexistence of lithospheric delamination related fast-wave speed anomalies in the upper mantle, and the absence of evidence for sudden, accelerated divergence of Nubia and Somalia. We focus on the Pliocene Gombe Stratoid Series and show how lithospheric thinning may result in pulsed magma generation from a plume-influenced mantle. By solving the 1D advection-diffusion equation using rates of plate thinning broadly equivalent to those measured geodetically today we show that despite elevated mantle potential temperature, melt generation may not occur and thereby result in extended intervals of quiescence. By contrast, an increase in the rate of plate thinning can generate magma volumes that are on the order of that estimated for the parental magma of the Gombe Stratoid Series. The coincidence of large-volume stratiform basalt events within the East African Rift shortly before the development of axial zones of tectonic-magmatic activity suggests that the plate thinning needed to form these stratiform basalts may herald the onset of the localization of strain.

Flood relief logistics planning for coastal cities: a case study in Shanghai, China
Pujun Liang, Jie Yin, Dandan Wang, Yi Lu, Yuhan Yang, Dan Gao, and Jianfeng Mai
Nat. Hazards Earth Syst. Sci. Discuss., https//doi.org/10.5194/nhess-2024-88,2024
Preprint under review for NHESS (discussion: open, 1 comment)
Addressing coastal city flood risks, this article examines relief logistics planning, employing a GIS-network analysis and optimization model to minimize costs and dissatisfaction. The investigation, grounded in Shanghai's emergency infrastructure and flood relief logistics framework, presents feasible distribution strategies. Meanwhile, the case study indicates that the supply levels of Emergency Flood Shelters and Emergency Reserve Warehouses vary in different coastal flood scenarios.