bluuebunny/crossref_metadata_2025 huggingface dataset:
Geochronological, petrological and tectonic implications of the Proterozoic massif-type anorthosite intrusions and related rocks from the northern Oaxacan Complex, southern Mexico
Authors: Elizondo Pacheco Luis Alejandro , Solari Luigi , He Hailong , Ramírez Fernández Juan Alonso , Maldonado Roberto
Published: March 2024

Massif-type anorthosite intrusions are enigmatic and significant crustal components widespread worldwide. They occur either as individual massifs or accompanied by mangerite, charnockite, and granite (AMCG suite). This Proterozoic phenomenon has been studied in numerous complexes, generating long-lasting discussions regarding the magmatic source and the tectonic setting where these rocks form. This controversy is still a matter of debate after decades of scientific research. In this sense, Mexico represents a unique and new opportunity to explore such petrological issues because its exposures of massive anorthosite and associated lithologies are mainly unstudied. These rocks are better exposed in the Oaxacan Complex, the most extensive Mexican inlier of Grenvillian rocks. This work is focused on its northern portion. This area is characterized by 1.4-1.1 Ga metamorphic rocks from the El Catrín and El Marquez units that were later intruded by anorthosite, gabbro, leucogabbro, oxide-apatite gabbronorites (OAGN), and granite bodies from the Huitzo suite. New LA-ICP-MS U-Pb zircon data revealed similar crystallization age ranges in the gabbro-anorthositic (1013-960 Ma) and granitic (1012-964 Ma) rocks. Their zircon Hf-O isotopic composition was compared with previous and new data from the older units of the area to assess the possible interaction between mantle- and crustal-derived melts during their generation. The intrusions of massive anorthosite and gabbro exhibit εHf(t) values of -2.54-4.79 and δ18O = 6.84-8.03‰. The granitic rocks have εHf(t) values of -0.79-2.87 and δ18O = 7.80-8.42‰. The lack of mantle-like εHf(t) and δ18O values suggests the participation of high-δ18O supracrustal material with more radiogenic Hf signatures during their generation. Simple binary mixing modeling indicates that the gabbro-anorthositic intrusions incorporated ~20-30% of metasedimentary country rocks, supporting a mantle-dominated origin. A slightly higher crustal component is recognized in the studied granitic intrusion. We also propose that these rocks permit an alternative model where Oaxaquia is paleogeographical relocated close to the eastern margin of Laurentia during the final stages of Rodinia amalgamation due to the resemblance in age to the late- to post-Grenvillian AMCG rocks (1016-956 Ma) outcropping there (e.g., Roseland, Mattawa, Labrieville, and Vieux Fort). This new tectonic view challenges the classical Amazonia-Oaxaquia-Baltica connection.
First results from the radiation belt monitors onboard the 6U CubeSat X-Ray Observatory NinjaSat
Authors: Kato Yo ,   NinjaSat Team
Published: March 2024

NinjaSat, a 6U CubeSat-sized (30 cm x 20 cm x 10 cm) X-ray observation satellite, was launched into a low Earth orbit at an altitude of 550 km in November 2023. NinjaSat is equipped with two 1U CubeSat-sized (10 cm x 10 cm x 10 cm) gas X-ray detectors (GMC) as primary detectors for astronomical observations of bright X-ray sources such as neutron stars and black holes. Initial operations of NinjaSat have been underway since January 2024.NinjaSat is also equipped with two radiation belt monitors (RBM) as sub-detectors to protect the GMCs from discharges in the gas cells potentially caused by excessive amount of incident charged particles. NinjaSat RBM uses a 9 mm x 9 mm Si-PIN photodiode to detect any increase in the count rate of either protons or electrons by exploiting the difference in the sensor's response to protons and electrons, and sends alert signals to GMCs which help ramping down high voltage applied to gas cells in the region of high charged particle rates. NinjaSat RBM is approximately 6% of the size of a 1U CubeSat in volume and weighs only 70 grams. Because NinjaSat RBM uses inexpensive, commercially available sensors and operates on an internal board independent of the primary detectors, it can be installed on other small satellites which need to monitor surrounding charged particle environment with relatively few development resources.Since NinjaSat will operate in a sun-synchronous orbit, a global map of charged particles can be obtained. We will present the development of NinjaSat RBM and the first results of charged particle maps in the radiation belt obtained during the initial operational period of NinjaSat.
Towards closing the Australian vertical land movement budget
Authors: King Matt , Ludwigsen Carsten Ankjær , Watson Christopher
Published: March 2024

GPS analysis of Australian vertical land motion (VLM) consistently suggests widespread subsidence of Australia of about 1-1.5mm/yr since ~2000, in contrast to most models of Glacial Isostatic Adjustment which predict motion closer to zero or slightly positive. These GPS findings have been corroborated by estimates from altimeter-minus-tide gauge measurements, suggesting they are robust within their terrestrial reference frame. Here we revisit the potential causes for this misfit, exploring a new reconstruction of global ice-loading changes and its impact on vertical land motion. We show this likely produces a subsidence of Australia of about 0.5mm/yr. We explore this in combination with estimates of hydrological, atmospheric and non-tidal ocean loading displacements. The residual signal is discussed within the context of different GIA model predictions, reference frame errors, and the possible impact of far-field postseismic signal.
Soil nitrogen cycling in dry lands: Precipitation legacy effects on microbial N loss pathways
Authors: Homyak Peter
Published: March 2024

The transition from dry-to-wet soils is often characterized by an acceleration of the nitrogen (N) cycle, representing a period of interest to biogeochemists studying future N cycling responses to global changes. In particular, wetting dry soils can produce large emission pulses of nitric oxide (NO; an air pollutant at high concentrations) and nitrous oxide (N2O; a powerful greenhouse gas), but the mechanisms governing the N losses remain unresolved. The asynchronous timing of when N becomes bioavailable and when ecosystem N sinks activate (e.g., plant N uptake) post wetting has often been used to explain why N is lost when dry soils wet up. However, other factors directly affecting nitrifying communities may also contribute to the emissions. For instance, ammonia oxidizing bacteria (AOB) may be favored over ammonia oxidizing archaea (AOA) in NH4+-rich environments that are typically observed in dry soils. Because AOB may process N less efficiently than AOA, shifts in nitrifier activity may help promote gaseous N losses. To better understand mechanisms for gaseous N loss, we studied drylands in southern California that can experience >6 months without rain, as well as other drylands where we added or excluded precipitation during the dry summer or wet winter seasons. We also selectively inhibited AOA and AOB communities to measure their contributions to soil N emissions. Excluding precipitation during the winter prior to collecting soils did not affect NO emissions, but either adding or excluding precipitation during the summer did; NO emissions after adding extra rainfall (95 ± 6 µg NO g soil-1; p = 0.01) or excluding rainfall (105 ± 22 µg NO g soil-1; p = 0.006) were significantly higher than the control (41 ± 6 µg NO g soil-1), with over 50% of the emissions controlled by AOB. While most of the effects of manipulating precipitation were observed on NO emissions, N2O increased only when we excluded precipitation in the winter wet season, averaging 0.58 ± 0.40 µg N-N2O g soil-1. Using isotopologues of N2O coupled with chloroform fumigations to slow microbial activity, we found that N retention and loss trade off as dry conditions intensify. Altogether, our measurements suggest that that shifts in precipitation patterns can favor AOB-derived NO emissions when dry soils are wetted at the end of the dry season, suggesting that shifts in nitrifier activity from the legacies of past precipitation can also help explain why N is lost when dry soils are wetted.
Comparison and understanding of sparse magnetization vector inversion
Authors: Ou Yang , Zhang Jie , Jia Dingyu , Li Yang , Yang Yi
Published: March 2024

Magnetization vector inversion (MVI) is an effective method for interpreting magnetic data without knowing the magnetization directions. Nevertheless, the serious nonuniqueness problem makes it difficult to obtain satisfactory results without proper constraints. Several constrained methods have been applied to the magnetization vector inversion to produce reliable results. To better understand these issues and provide some improvements, we compared and evaluated different forms of magnetization vector inversion: (1) magnetization vector inversion in Cartesian coordinates (MVI-C); (2) magnetization vector inversion in spherical coordinates (MVI-S); and (3) compact magnetization vector inversion with magnitude constraints. Magnetization vector inversion incorporates prior information or assumptions about subsurface geological structures into the model objective function and solves the optimal problem with respect to the data and the model objective function to recover the desired features. We first analyze different model objective functions and then test these methods against synthetic and real datasets. Theoretical analysis and tests reveal that the linear relationship in the rectangular coordinate system simplifies the calculation process, but it is difficult to apply reasonable constraints, which results in a lack of correlation in the direction of magnetization; moreover, the distribution is not concentrated. It is easy to constrain the magnetization magnitude and direction in the spherical coordinate system, and better results can be obtained. However, due to the nonlinear relationship, the calculation complexity increases, and the inversion results are heavily dependent on the initial model. The method based on the modulus constraint establishes the relation between components in the Cartesian coordinate system, but the direction cannot be constrained. Therefore, we believe that the magnitude and direction of magnetization should be constrained simultaneously in the rectangular coordinate system to obtain a fast, stable, and accurate inversion method.
The role of magma intrusions on faulting mechanisms during pre-eruptive seismic swarms in the Reykjanes Peninsula
Authors: Rodriguez Cardozo Felix Rodrigo , Braunmiller Jochen , Sadeghi Chorsi Taha , Mendo Pérez Gerardo , Hjörleifsdóttir Vala , Jónsdóttir Kristín , Cubuk Sabuncu Yesim , Thompson Glenn , McNutt Stephen , Dixon Jacqueline , Dixon Timothy , Malservisi Rocco
Published: March 2024

In March 2021, a fissure eruption in Fagradalsfjall marked the onset of the first volcanic activity in over 800 years on the Reykjanes Peninsula, Iceland. Since then, three more fissure eruptions occurred in August 2022, July 2023, and December 2023. Intense seismic swarms that included Mw≥ 4.0  earthquakes preceded all eruptions. Concurrently with swarm activity, large surface deformations related to magma intrusions were observed by Interferometric Synthetic Aperture Radar (InSAR), and Global Navigation Satellite System (GNSS) data. Ground displacements exceeded the deformation expected from earthquakes by far, suggesting the intrusion process was primarily aseismic. However, the intrusions may have influenced the prevalent earthquake faulting style in the pre-eruptive swarms. For instance, seismic moment tensors before and during the early 2021 swarm indicate that right-lateral bookshelf faulting along roughly north-south trending strike-slip faults dominated seismic deformation. This changed to more northeast-southwest oriented oblique-normal to normal faulting mechanisms for the later swarms consistent with graben formation after a dyke intrusion. Seismic moment release during the 2021 seismic swarm, which included ten relatively large Mw 5+ earthquakes, was larger than for subsequent swarms, where only a few events reached Mw 5. This may indicate that the 2021 intrusion, which marked a reawakening of volcanic activity, may have triggered bookshelf faults close to failure that might have otherwise ruptured in the near term due to the underlying oblique rifting.  The transition of source mechanisms toward oblique and normal faulting during the later swarms, though, may reflect an active role of the intrusion processes on fault orientation of triggered seismicity rather than simply inducing seismicity on pre-existing faults. 
Upland Hillslope Groundwater Subsidy Affects Low-Flow Storage–Discharge Relationship
Authors: Ameli Ali , Li Hongyi
Published: March 2024

Large-scale cross-site scientific synthesis on low-flow storage–discharge relation can promote developing transferable hypotheses on the interactions among critical zone attributes and on how such interactions affect catchments’ water vulnerabilities. This study leverages cross-site empirical and theoretical analyses and develops a similarity index, based on the interactions among critical zone attributes, to help determine the less-explored influence of upland hillslope groundwater subsidy on storage–discharge relation. We show that an increase in the relative extent of upland hillslope groundwater subsidy to low-flow discharge, occurring through deep slow low-moving (e.g., bedrock) storage unit, leads to (a) an increase in the nonlinearity of low-flow discharge sensitivity to storage (β1) and (b) an increase in the convexity of low-flow storage–discharge relation. Our findings also raise new hypotheses on the applicability of Boussinesq-based hydraulic groundwater theory at low-flow condition. Empirical results show that in a portion of our study catchments, particularly in those with a relatively small extent of upland hillslope groundwater subsidy, the theory’s proposed range of nonlinearity sufficiently explains the nonlinearity of low-flow storage–discharge relation. However, in catchments with a strong influence of upland hillslope groundwater subsidy through deep slow-moving storage unit, the current state of hydraulic groundwater theory, using one single (non)linear representative storage unit, may not be sufficient to explain the large nonlinearity and convexity of low-flow storage–discharge relation (or the long tail of hydrograph late recession). Considering β1 informs the low-flow vulnerability of catchments, the findings of this study deepen and generalize our understanding of where low-flow discharge is vulnerable to storage’s change.
Differentiable modeling for soil moisture retrieval by unifying deep neural networks and water cloud model
Authors: Li Zhenghao , Yuan Qiangqiang
Published: March 2024

Machine learning has been widely used in surface soil moisture (SSM) retrieval studies, but in recent years, this purely data-driven retrieval method has been controversial due to its lack of physical interpretability and generalization ability. Physical retrieval models based on the theory of radiative transfer equations respect physical laws, but their retrieval accuracy is generally lower than that of machine learning retrieval methods. In order to explore the retrieval method of unifying these two types of models to maximize the advantages of integrating machine learning models and physical models in the retrieval process, this study took high-resolution soil moisture retrieval as an example, and constructed a differentiable model (DM), which was based on the differentiability of neural networks, and united the water cloud model (WCM) and neural networks by implementing differentiable programming of the WCM in a machine learning platform. The differentiable soil moisture retrieval model took the WCM as the skeleton, and realized SSM retrieval with 10 m resolution based on synthetic aperture radar data, optical data and other auxiliary data. Relying on the DM, we have successfully transformed the problem of physical model parameter calibration into a neural network training problem, which made the retrieval model physically interpretable while allowing the model to be trained using gradient descent for more accurate retrieval results. In addition, the model was comparatively evaluated from multiple perspectives to demonstrate its advantages over machine learning retrieval models and physical retrieval models. This study provides new ideas for the combination of machine learning and physical knowledge in other retrieval studies, and provide new cases for physical knowledge-guided machine learning research in earth sciences.
Propagation Process of Long Ocean Wave from the Yellow Sea to the Korea Strait in Spring 2019
Authors: Kwon Kyungman , Myoung Sung-Gwan , Choi Byoung-Ju , Jeong Kwang-Young
Published: March 2024

Meteotsunami, which cause fluctuations on the sea surface, occur due to atmospheric pressure jumps and atmospheric gravity waves. This is a long ocean wave with almost the same spatio-temporal scale as regular tsunamis, causing significant damage to coastal areas. To understand the relationship between meteotsunami and climate change in Korea, research on the genesis and development processes of meteotsunami is necessary. This study examines the generation and propagation process of a meteotsunami that occurred in the Korea Strait on April 7, 2019, using observational data and numerical models. Coastal tidal observation stations detected a meteotsunami in the Korea Strait, characterized by oceanic long waves with heights ranging from 0.2 to 0.9 meters and a period of about 60 minutes. Atmospheric pressure jumps, starting in the Yellow Sea and moving into the Korea Strait, propagated in succession, observed to range from 2 to 4 jumps with magnitudes of 1.5 to 3.9 hPa. Analysis of meteorological data showed that the isobars of the atmospheric pressure jumps were oriented eastward in a counterclockwise direction at angles of 75 to 83 degrees, moving at speeds of 26.5 to 31.0 m/s. The Regional Ocean Model System (ROMS) was used to reproduce this meteotsunami's generation and propagation process. Numerical model results indicated that long ocean waves were amplified in the southwestern part of the Yellow Sea with depths greater than 75 m due to Proudman resonance. This long ocean wave refracts towards the coast in shallow areas north of the Korea Strait, with refraction and reflection by offshore islands influencing the wave heights at the coast. In particular, the high maximum amplitude of long ocean wave in Masan Bay is mainly due to refraction and reflection by nearby islands, increasing the amplitude by approximately 72.7%. Sensitivity experiments were conducted to examine the relationship between the height changes of long ocean wave on the coast and the speed and angle of the atmospheric pressure jumps moving from west to east across the Korea Strait. In the numerical model experiments, atmospheric pressure jumps moving at angles of 80 to 118 degrees and speeds of 27 to 30 m/s significantly increased the amplitude of the ocean long waves. Regionally, Seogwipo and Goheung showed increased amplitudes at speeds of 24 to 30 m/s and were relatively less affected by the angle. In Masan, the maximum amplitude of sea surface oscillation occurred when the atmospheric pressure jump moved at angles of 85 to 100 degrees at a speed of 30 m/s.
Observing a Volatile Organic Compound from a Geostationary Infrared Sounder: HCOOH from FengYun-4B/GIIRS
Authors: Zeng Zhao-Cheng , Franco Bruno , Clarisse Lieven , Lee Lu , Qi Chengli , Lu Feng
Published: March 2024

Formic acid (HCOOH) is one of the most abundant volatile organic compounds (VOCs) in Earth’s atmosphere and an important source of atmospheric acidity. Satellite observations play an indispensable role in improving our understanding of global HCOOH sources and sinks. However, existing polar-orbiting satellites that are sensitive to tropospheric HCOOH provide only two daily overpasses over the same location, one during the day and the other at night. The diurnal changes of tropospheric HCOOH are therefore under-constrained, limiting our ability to monitor its evolution and transport throughout the troposphere. The Geostationary Interferometric Infrared Sounder (GIIRS) onboard China’s FengYun-4 satellite series is the world’s first geostationary hyperspectral infrared sounder. Here, we present the first retrieval of HCOOH from GIIRS onboard FengYun-4B. Results from July 2022 to June 2023 highlight the seasonal variation of the HCOOH distribution in Asia driven by biomass burning emissions and biogenic sources. Sensitivity to HCOOH peaks during daytime and decreases at night, following diurnal changes of thermal contrast between the surface and the atmosphere. FY-4B/GIIRS in the geostationary orbit will offer important information with its high temporal resolution to improve our understanding of the production, evolution, and loss processes of HCOOH in the atmosphere. Furthermore, cross-validation with IASI HCOOH data shows good agreement, indicating that observations from FY-4B/GIIRS have comparable sensitivity to IASI.
Modelling of sedimentation-regulated methane ebullition from reservoirs
Authors: Ma Enze , Liang Xiuyu , Zhuang Qianlai , Li Zhe , Feng Lian , Chen Kewei , Zhang Jiangwei , Zhang You-kuan
Published: March 2024

Ebullition is a primary pathway of CH4 emission from water reservoirs, which is poorly constrained due to its episodic nature, especially in large reservoirs. Here, by inducing the intrinsic link between sedimentation and CH4 production, and hence ebullition, a novel mechanistic reservoir CH4 model is developed for quantifying CH4 emissions from reservoirs. The model is first validated and applied in the Saar River reservoirs, effectively reproducing the seasonal patterns of ebullitive fluxes and the enhanced effects of sedimentation on ebullition. Through analyzing modelling CH4 production, bubble formation, dissolved CH4 concentration in sediments, and their interplay at different sedimentation rates, the regulatory mechanisms of sedimentation on ebullition are investigated. The results indicate that the increase in sedimentation rate augments sediment CH4 production. Excessive CH4 production beyond diffusive transport in the sediment is required to induce porewater CH4 super-saturation and trigger bubble generation. Under porewater super-saturation, the majority of the increased sediment CH4 production, resulting from an elevated sedimentation rate, is released via ebullition. Thus, sedimentation can regulate reservoir CH4 bubble formation and ebullition by influencing CH4 production. Then, the proposed model is applied to estimating CH4 emissions from the Three Gorges Reservoir (TGR). The TGR have trapped 80% sediments derived from the upstream Yangtze River since dam closure, potentially fueling CH4 production and ebullition, which has not been quantified yet. We find that the CH4 flux of the TGR is 6.71 (4.12-11.41) mg CH4-C m-2d-1 with 3.07 (0.90-6.06) mg CH4-C m-2d-1 via ebullition and 3.64 (1.88-5.35) mg CH4-C m-2d-1 via diffusion. This flux is 36% larger than other estimates in the literature. By trapping most of the sediments from upstream, the TGR experiences a surge in CH4 emission from 0.17 to 1.38 Gg CH4-C yr-1 after impoundment, mainly via ebullition (0.63 Gg CH4-C yr-1). Ebullition is highly related to the sedimentation along the channel. The proposed model provides a mechanistic approach for estimating reservoirs ebullition and introduces a new aspect for the effects of reservoir sedimentation on river carbon budget.
Emergence of scaling properties in momentum-scalar coupling turbulence: Exploring interplay of multiphysics mechanisms
Authors: Zhao Wei
Published: March 2024

Momentum-scalar coupling turbulence, such as buoyancy-driven turbulence and electrohydrodynamic (EHD) turbulence, involves the transportation of multicomponent scalars under the strong interplay of multiphysics. For instance, in the atmosphere, the temperature gradient can induce buoyancy, driving the flow to form thermal convection. At the same time, electric body force can be generated on droplets, dust, and moisture gradients through spatial electric fields, resulting in air flow into EHD turbulence. Additionally, charged species move and create electric current, leading to Lorentz force due to the magnetic field of the earth, which may induce magnetohydrodynamic (MHD) turbulence. These physical mechanisms generate the diverse phenomena on our beautiful planet. This study theoretically explores how multiphysical mechanisms interplay, governing the cascades of turbulent kinetic energy and multicomponent scalars. Some new scaling properties, which differ from those predicted in buoyancy-driven turbulence, EHD, and MHD, emerge when two mechanisms and scalar components exist simultaneously. The quad-cascade processes of such turbulent systems are again validated. Unfortunately, when three or more mechanisms are taken into account at the same time, the problem becomes unattainable to close. This research endeavors to shed light on the diverse observation in momentum-scalar coupling turbulence across various scenarios.
Modeling regional nitrogen cycle in the atmosphere: present situation and its response to the future emissions control strategy
Authors: Shen Ao , Liu Yiming , Fan Qi
Published: March 2024

Reactive nitrogen (Nr) cycle in the atmosphere has an important affection on terrestrial ecosystems, which has not been fully understood and its response to the future emissions control strategy is not clear. Taking the Yangtze River Delta (YRD) as an example, we explored the regional Nr cycle (emissions, concentrations, and depositions) and its source apportionment in the atmosphere in January (winter) and July (summer) 2015 and projected its changes under emissions control by 2030 using the CMAQ model. We examined the characteristics of Nr cycle and found that Nr suspends in the air mainly as NO, NO2, and NH3 gases and deposits to the earth’s surface mainly as HNO3, NH3, NO3-, and NH4+. Due to the higher NOx than NH3 emissions, oxidized nitrogen (OXN) but not reduced nitrogen (RDN) is the major component in Nr concentration and deposition, especially in January. Nr concentration and deposition show an inverse correlation, with a high concentration in January and low in July but the opposite for deposition. We further apportioned the regional Nr sources for both concentration and deposition using the Integrated Source Apportionment Method (ISAM) incorporated in the CMAQ model. It shows that local emissions are the major contributors and this characteristic is more significant in concentration than deposition, for RDN than OXN species, and in July than in January. The contribution from North China (NC) is important for Nr in YRD, especially in January. In addition, we revealed the response of Nr concentration and deposition to the emission control to achieve the target of carbon peak in the year 2030. After the emission reduction, the relative responses of OXN concentration and deposition are generally about 100% to the reduction of NOx emissions (~50%), while the relative responses of RDN concentration are higher than 100% and the relative responses of RDN deposition are significantly lower than 100% to the reduction of NH3 emissions (~22%). Consequently, RDN will become the major component in Nr deposition. The smaller reduction of RDN wet deposition than sulfur wet deposition and OXN wet deposition will raise the pH of precipitation and help alleviate the acid rain problem, especially in July.
Spatiotemporal fusion of multi-source Chinese Gaofen remote sensing data for mapping costal wetland using stacking ensemble classification method
Authors: Liu Yitong , Bao Nisha , Qian Huiya , Meng Dantong
Published: March 2024

The precise mapping of coastal wetlands holds great significance in the context of monitoring carbon sequestration and storage within coastal ecosystems, particularly in light of climate change and human-induced activities. Time series and multi-source remote sensing data offers distinct advantage in the spatial and temporal mapping of land use, particularly in wetland systems, encompassing various types of vegetation. The primary aim of this study was to delineate the spatial distribution of land use within the Liao River Delta (LRD) wetland. This was achieved by employing a stacking ensemble model that integrated time series GaoFen-1 (GF-1) optical imagery, GaoFen-3 (GF-3) synthetic aperture radar (SAR) imagery, and Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) imagery. The first step involved the application of the enhanced spatial and temporal adaptive reflectance fusion model (ESTARFM) to fuse the GF-1 NDVI and MODIS NDVI datasets, resulting in the production of time series NDVI data. Subsequently, the parameters pertaining to vegetation phenology were obtained by employing the threshold method on time series NDVI data. We compiled feature datasets that encompassed GF-1 spectral bands, spectral indices, phenological parameters, and GF-3 SAR features. In order to mitigate data redundancy, the Recursive Feature Elimination and Cross-Validation (RFECV) model was employed to identify and select significant features. Finally, the stacking ensemble model was constructed by combining five base models [K-Nearest Neighbors (KNN), Random Forest (RF), Adaptive Boosting (AdaBoost), Extreme Gradient Boosting (XGBoost), and Light Gradient Boosting Machine (LightGBM)] to perform wetland classification. The findings showed the following: (1) ESTARFM was able to successfully fuse GF-1 NDVI and MODIS NDVI data, resulting in a spatiotemporal fusion with a coefficient of determination (R2) of 0.85 and a root mean square error (RMSE) of 0.07. (2) In the process of wetland classification, the RFECV algorithm was employed to select relevant features. Specifically, 75 spectral band features, 89 spectral index features, 13 SAR features, and 7 phenological parameters were identified as significant for this task. (3) A stacking ensemble model was constructed using the aforementioned multi-source features. This model exhibited a robust and consistent performance in wetland classification, achieving the highest overall accuracy of 94.33%. Notably, this accuracy improvement ranged from approximately 0.09% to 10.02% when compared to the individual base models. Thus, the present study has the potential to be utilized in the context of fine-scale wetland monitoring, thereby offering valuable assistance to the field of wetland environmental research.
Preliminary Results of Material Transport Model of Rigid Block Extrusion Driven by Crustal Flow Beneath the SE Tibetan Plateau: insights from high-resolution 3-D Magnetotelluric Imaging
Authors: Ye Gaofeng , Sang Wenbo , Wei Wenbo , Jin Sheng , Lei Qing , Dong Hao
Published: March 2024

     The collision between the Indian and Eurasian plates in the Cenozoic eras resulted in the formation of the world's largest and highest plateau. The intensive collision, subduction, and related deep dynamic processes led to significant crustal shortening, uplifting, and expansion of the Plateau, accompanied by eastward extrusion of plateau materials. The southeastern Tibetan Plateau (SETP) is one of the most important channels for escaping plateau materials. The widespread existence of crustal weak material flow in the SETP has become widely accepted. However, previous research has mostly been limited to two-dimensional profiles or spaced data measurement points. Therefore, obtaining reliable and high-resolution geophysical models of the lithosphere is crucial for understanding the deformation mechanisms of the plateau.    Our three-dimensional resistivity model shows unprecedented resolution of the Simao Block of the Indochina Block, offering new insights into the material transport and deformation mechanisms of the SETP. Two consecutive large-scale high-conductivity anomalies observed in the middle-lower crust are speculated to be partial melting associated with crustal flow. The rigid lithosphere separated by significant strike-slip faults on the SETP may be pulled by ductile materials flow, where plastic flows in the middle-lower crust drive the rigid blocks to extrude and escape along the boundary faults, thus dominating the deformation of the lithosphere. The large-scale delamination of the continental lithosphere leads to upwelling of the asthenosphere along mechanically weak areas. Upwelling hot materials continue to heat the entire crust, and the expanding and diffusing lower crust further accelerates partial melting and plastic flow in the middle-lower crust.
Variation Martian proton aurora in different timescales
Authors: Wu Jingyi , He Fei , Wei Yong , Hughes Andrea
Published: March 2024

The aurorae on Mars are divided into diffuse aurora, discrete aurora and proton aurora. Proton aurora is the most common type of aurora on Mars. The proton aurora on Mars is formed when protons in the solar wind pass through the Martian hydrogen corona and undergo charge exchange to form energetic neutral atoms, which deposit energy in the Martian atmosphere. Previous research results showed that the main external factors that affect the occurrence rate, emission enhancement, intensity and peak height of proton aurora are the solar wind particle flux and velocity, solar zenith angle and solar longitude. Here, we extend the previous proton aurora database compiled by Hughes et al. [2019], which was in the descending phase of the last solar cycle between 2014-2018, to present with similar algorithm. Using this new database covering almost one solar cycle, we investigated the long-term variations of the proton aurora on Mars in three timescales, including the solar rotation cycle, Martian season, and solar cycle. The results will help us understand the solar wind-Mars interactions.
Nitrogen Stimulation of Plant Biomass Growth Mediated by Foliar Magnesium and Calcium Worldwide 
Authors: Xu Xia
Published: March 2024

Liebig’s Law of the Minimum underscores the need for balanced nutrition for optimal plant growth; any deficiency in essential nutrients can influence plant growth and subsequent biomass accumulation. Anthropogenic nitrogen (N) deposition can alleviate the prevailing N limitation and stimulate plant growth in many terrestrial ecosystems, thereby helping to mitigate climate change. However, the N stimulation effects may diminish under conditions where plant growth is limited by soil cation availability that is susceptible to N-induced soil acidification. How variation in soil cations influences N stimulation of plant growth is unresolved. Here, we synthesized data from 282 field experiments and found that in agreement with the optimal allocation theory, N addition asymmetrically increased plant biomass aboveground (42.5 ± 7.4%) and belowground (20.8 ± 10.1%). The increment in aboveground biomass was soil pH dependent, shifting from neutral in low pH (pH ≤ 4.5) to positive in medium (4.5 < pH ≤ 7.5) and high pH (pH > 7.5) soils. In contrast, changes in belowground biomass were independent of soil pH. The variations in biomass increments across different soil pH ranges were mediated by the levels of foliar magnesium (Mg) and calcium (Ca), with the responses exhibiting a shift from negative in low pH soils to neutral in medium and high pH soils. These findings suggest that reduction in foliar Mg and Ca levels diminishes the N stimulation of plant biomass despite the enhancement of root growth in low pH soils. Given the widespread stimulation of plant biomass through N addition, the extent of this effect is soil pH dependent and mediated by the foliar cation status of plants.
Hydrogeochemical Characteristics and Genetic Mechanisms of Geothermal Fields in the Xi'an Depression of the Weihe Basin
Authors: Liu Jian , Ren Zhanli , Yu Qiang , Yan Xinyun , Qi Kai , Wang Zhen , Guo Sasa , Lan Huaping , Jia Mingxing , Liu Yanzhao
Published: March 2024

The geothermal resources in sedimentary basins have high potential for development and utilization, and have become an important research topic worldwide(Olasolo et al.,2016; Pasvanoğlu and Çelik., 2019; Duan et al.,2022). This paper focuses on the genetic mechanism and evolution process of deep geothermal water were explored through the analysis of hydrogeochemical and isotope geochemical data, which can provide technical and theoretical support for the sustainable development of geothermal fields in the Weihe basin. The study indicates that: (1)the hydrochemical type of geothermal water of Dongda geothermal field are predominantly HCO3·SO4-Na type. Meanwhile, the hydrochemical type of geothermal water of the northern Xi'an Depression are mainly SO4·HCO3-Na and SO4·HCO3·Cl-Na types. The ionic fraction is primarily influenced by the dissolution of silicate and evaporite minerals, as well as alternating cation adsorption. (2) Geothermal water is primarily recharged by atmospheric precipitation originating from the Qinling Mountains. The recharge elevation ranges from 677.94 m to 1467.65 m. (3) The Dongda geothermal field has a thermal storage temperature ranging from 50.19℃ to 80.29℃, and a depth of thermal circulation ranging from 1126.32 m to 2129.62m. Meanwhile, the northern Xi'an depression has a thermal storage temperature ranging from 73.17℃ to 109.50℃, and a depth of thermal circulation ranging from 1892.41 m to 3103.22 m. (4) The δ18O of the geothermal water in the northern Xi'an depression is more significantly shifted to the right of the atmospheric precipitation line than that of the Dongda geothermal water, indicating a significant “oxygen drift”.(5) The Dongda geothermal reservoir in the southern Xi'an Depression mainly experiences heat transfer through convection, while the geothermal reservoir in the northern Xi'an depression experiences heat transfer through conduction.References[1]Duan, R., Li, P., Wang, L., He, X., & Zhang, L. (2022). Hydrochemical characteristics, hydrochemical processes and recharge sources of the geothermal systems in Lanzhou City, northwestern China. Urban Climate, 43, 101152.[2]Olasolo, P., Juárez, M. C., Morales, M. P., & Liarte, I. A. (2016). Enhanced geothermal systems (EGS): A review. Renewable and Sustainable Energy Reviews, 56, 133-144.[3]Pasvanoğlu, S., & Çelik, M. (2019). Hydrogeochemical characteristics and conceptual model of Çamlıdere low temperature geothermal prospect, northern Central Anatolia. Geothermics, 79, 82-104.
Significant reduction of unequal population exposure to climate extremes by achieving the carbon neutrality
Authors: Choi Jung , Oh Seok-Geun , Kang Min-Jee , Jeong Sujong , Min Seung-Ki , Yeh Sang-Wook , Kim Yeon-Hee , Son Seok-Woo
Published: March 2024

Climate extremes, such as hot temperature and heavy precipitation events, have devastating effects on human societies. As the planet warms, they have become more intense and more frequent. To avoid irreversible damage from climate extremes, many countries have committed to achieving net-zero anthropogenic carbon emissions, or carbon neutrality, by 2050s. Here, we quantify the impact of carbon neutrality on population exposure to climate extremes using multi-model projections from the Coupled Model Intercomparison Project Phase 6 (CMIP6) based on the Shared Socioeconomic Pathway (SSP)1-1.9 and SSP3-7.0 scenarios. It is found that the increasing exposure of the population to hot-temperature and heavy-precipitation extremes can be substantially reduced by 87–98% in the late 21st century by achieving carbon neutrality. The benefits of carbon neutrality are particularly pronounced in Africa and Asia. The potential benefits of carbon neutrality are also significant in North America, Europe, and Oceania, where a reduction in climate extremes is more than twice as important as population decline in reducing population exposure to climate extremes. These results provide important scientific support for ongoing efforts to achieve net-zero carbon emissions by 2050s to reduce potential climate risk and its inequity across continents.
Influence of Extreme Weather and Climate Events on Crop Yields in China
Authors: Yin Dezhen , Li Fang
Published: March 2024

Extreme weather and climate events, such as extreme temperatures, droughts, and floods, cause significant yield losses and threaten global food security. Their frequency and intensity have increased in recent decades, a trend expected to continue. China is the world's largest grain producer and also a country where extreme events occur frequently. Nevertheless, the influence of extreme weather and climate events on crop yields in China is not yet well understood. This study quantified the impact of heat waves, frost, droughts, and floods on the yields of wheat, maize, rice, and soybean in China from 1970 to 2019, using the superposed epoch analysis (SEA) method, agricultural statistics collected from the National Bureau of Statistics of China, and crop calendar reanalysis dataset. Furthermore, the performance of 13 global gridded crop models (GGCMs) in simulating these impacts is evaluated. The results show that heat waves, frost events, droughts, and floods significantly decrease crop yields by 2.1%, 1.0%, 2.2%, and 1.7% for wheat, maize, rice, and soybean, respectively, accounting for 23.6%, 10.5%, 21.4%, and 18.9% of the interannual variability. Yields of different crop types in China are sensitive to specific extreme weather events. The GGCMs effectively capture the impact of droughts, with nine out of thirteen models detecting a significant effect, yet they struggle to accurately simulate the effects of heat waves, frost events, and floods, with only five, two, and two models detecting these impacts, respectively.
Meso-Neoarchean coupled crust-mantle differentiation followed by gravity-driven lithospheric delamination and subduction initiation in the North China Craton
Authors: Liu Jianhui
Published: March 2024

The geodynamic regime driving formation of Archean felsic continent crust is still an ongoing debated and unsolved fundamental issue. The episodic Archean TTGs and associated granitoids, with emplacement ages of ca. 2.9, 2.7 and 2.5 Ga, occurred in the Jiaobei Terrane, North China Craton (NCC), provide prolonged continuous records of formation processes of Meso-Neoarchean felsic continental crust. To track patterns of crust-mantle differentiation, crustal reworking and recycling, and accordingly, constrain underlying geodynamic regimes associated with formation of the Meso-Neoarchean felsic continental crust, we present comprehensive zircon U-Pb dating, Hf-O isotopes and whole-rock major- and trace-element geochemical data for the episodic Archean TTGs and associated granitoids. The comprehensive dataset decodes the generation of the episodic Archean TTGs over wide-range pressure conditions from amphibolite to eclogite facies and Meso-Neoarchean coupled crust-mantle differentiation, which was likely driven by episodic hot mantle (plume) upwelling. In addition, the ca. 2.9 and 2.7 Ga TTGs shared identical Mesoarchean juvenile crust source and exhibit consistent mantle-like zircon δ18O values, whereas the ca. 2.5 Ga TTGs mainly derived from distinctly younger Neoarchean juvenile crust, implying removal and replacement of the Mesoarchean juvenile lower crust. Importantly, some ca. 2.5 Ga TTGs, granitic gneisses and sanukitoids exhibit significantly higher zircon δ18O values than mantle δ18O values, demonstrating occurrence of Neoarchean supracrustal recycling. Consequently, the combined geochemical dataset with geological evidence allow us to track the geodynamic processes for the formation of the Meso-Neoarchean felsic continent crust in the Jiaobei Terrane, NCC: Episodic hot upwelling mantle (plume)-lithosphere interactions at ca. 2.9, 2.7 and 2.5 Ga resulted in the coupled crust-mantle differentiation over different depths to produce the spatial-temporally coexisted various-pressure-type TTGs, juvenile crust and voluminous dense lower crustal restite, respectively. Subsequently, dense lithospheric delamination triggered by gravitational instability occurred, followed by continental uplifting, subduction of altered oceanic crust, and asthenosphere and mantle-derived mafic melts upwelling, resulting in extensive occurrences of anatexis and metamorphism with anticlockwise P-T paths in the medium-lower crust at ca. 2.5 Ga. Along with large-scale melting and cooling of mantle, thick stable craton lithosphere with strong rigidity and viscosity had likely developed by the end of Neoarchean. The geodynamic processes in Meso-Neoarchean were likely diverse, especially episodic hot upwelling mantle (plume) -lithosphere interaction could be a favored geodynamic regime responsible for formation of Archean felsic continental crust in the Jiaobei Terrane, NCC.
Exploration on the Feasibility and Mode of the Whole River Water and Sediment Regulation in the Yellow River Basin
Authors: Zhang Ling , Wang Yuanjian
Published: March 2024

In the past decades，some progress has been made in the theory and practice of water and sediment regulation of the Yellow River．However，under the current engineering conditions, the feasibility and model of the whole river water and sediment regulation combined with the cascade reservoirs of Long ( Longyangxia) , Liu ( Liujiaxia) , Wan ( Wanjiazhai) , San ( Sanmenxia) and Xiao ( Xiaolangdi) are rarely discussed.  Based on a comprehensive analysis of the adjustable water volume of the Long-Liu cascade reservoirs, interval inflow and diversion water volume of the whole river under the multi-year average condition, this paper demonstrated the feasibility of the whole river water and sediment regulation under the current engineering conditions.  Two modes were put forward including the conventional mode and the unconventional mode, and the effects of two modes were compared and analyzed.  The results show that the sediment discharge of Xiaolangdi Reservoir under the two modes is 145.1 million tons and 191.3 million tons respectively and the sediment deposition of the downstream channel is 11.3 million tons and 22.1 million tons respectively.  No matter which mode of water and sediment regulation is adopted, Xiaolangdi Reservoir can achieve effective erosion in reservoir during the period of discharging before flood, and at the same time, it has little influence to the siltation of river channe.  Therefore, under the premise of strengthening the fine operation of the reservoir and strict interval diversion management, the whole river water and sediment regulation mode under the current engineering conditions is completely feasible.
Contributions of Arctic Sea-ice Loss and East Siberian Atmospheric Blocking to 2020 Record-breaking Meiyu-baiu Rainfall
Authors: Chen Xiaodan , Wen Zhiping , Dai Aiguo
Published: March 2024

Heavy Meiyu-Baiu rainfall occurred over central-east China and Japan in June-July 2020. This study analyzes observational and reanalysis data and performs atmospheric model simulations to investigate its causes. It is found that low Arctic sea ice cover (SIC) in late spring-early summer of 2020 along the Siberian coast was an important factor. The low SIC caused local warming and high pressure, resulted in excessive atmospheric blockings over East Siberia, which caused cold air outbreaks into the Meiyu-Baiu region, stopped the seasonal northward march of the Meiyu-Baiu front, and increased the thermal contrast across the front, leading to record-breaking rainfall in June-July 2020. Our results suggest that the 2020 extreme Meiyu-Baiu was partly caused by the low SIC around the Siberian coast through its impact on East Siberian blockings. Further analysis shows that Indian Ocean warming and the Arctic sea-ice loss has combined effect on the particularly heavy rainfall in July 2020.  Their effects are interdependent rather than additive. Strong IO warming is rarely observed alongside severe Arctic sea-ice loss before 2020 because of their discordant interannual variations. In the future, the combined effects of IO warming and Arctic sea-ice loss on the Meiyu-Baiu rainfall may become more pronounced as their long-term trends continue. 