bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of velocity and thermal structure in the construction of asymmetric rifted margins
Authors: dos Santos Souza Sara , Salazar-Mora Claudio Alejandro , Sacek Victor
Published: March 2024

The development of asymmetric conjugate rifted margins has been explained by processes such as rift migration and sequential faulting (Brune et al., 2014; Ranero & Pérez-Gussinyé, 2010), and by the effects of lithospheric strength and strain-softening (Svartman Dias et al., 2015; Huismans & Beaumont, 2003) during rifting. Briefly, rift migration consists of sequential faulting of the upper crust that moves oceanward and is associated with lower crustal flow. Nonetheless, there are other thermal and dynamic parameters that might either facilitate or hinder the construction of an asymmetric margin, also depending on the coupling degree between the continental and mantle lithosphere. Since there are a considerable number of asymmetric margins around the world, mostly associated to petroleum fields, and more recently emerging as green hydrogen reservoirs, there is a need to understand which and how much the parameters influence the construction of asymmetric margins during the rifting phase. For that reason, this work aims to contribute to the understanding of this subject through thermo-mechanical numerical models. Velocity and thermal structure were the principal factors considered in the context of a decoupled lithosphere. Our models show that rift velocity is the principal parameter that controls width and margin asymmetry, being followed by thermal structure. High rift velocities (~5 cm/year) developed wide and asymmetric margins, while a thick upper crust is shown to be crucial to develop the distal domain in the late stages of rifting. When both parameters are combined, the generated margins can reach about 360 km long. In some scenarios, the margin width is up to 550 km, with a distal domain which exceeds 130 km long.Funded by Petrobras Project 2022/00157-6. Brune, S. et al. Rift migration explains continental margin asymmetry and crustal hyper-extension. Nature communications, v. 5, n. 1, p. 4014, 2014.Huismans, R. S. & Beaumont, C. Symmetric and asymmetric lithospheric extension: Relative effects of frictional-plastic and viscous strain softening. Journal of Geophysical Research: Solid Earth, v. 108, n. B10, 2003.Ranero, C. R. & Pérez-Gussinyé, M. Sequential faulting explains the asymmetry and extension discrepancy of conjugate margins. Nature, v. 468, n. 7321, p. 294-299, 2010.Svartman Dias, A. E. et al. Conjugate rifted margins width and asymmetry: The interplay between lithospheric strength and thermomechanical processes. Journal of Geophysical Research: Solid Earth, v. 120, n. 12, p. 8672-8700, 2015.
Horizontally Explicit Vertically Implicit (HEVI) Time-Integrators for a Non-Hydrostatic Whole Atmosphere Models
Authors: Kelly James F. , Giraldo Francis X. , Reinecke P. Alex , Alves Felipe , Barton Cory A. , Eckermann Stephen D.
Published: March 2024

The U.S. Navy is building a coupled thermosphere-ionosphere prediction system.  As part of this project, we are developing a new dynamical core (DyCore) extending from the ground to the exobase (~500 km).  The DyCore must be able to handle large variations in both temperature and composition, which motivates a new Horizontally Explicit Vertically Implicit (HEVI) time integrator.  Unlike traditional linear Implicit-EXplicit (IMEX) methods commonly used in numerical weather prediction (NWP), HEVI does not require a fixed reference state.  Our DyCore combines HEVI with a Specific Internal Energy Equation (SIEE) and a Spectral Element Method (SEM) spatial discretization to form a robust, whole-atmosphere model for the neutral atmosphere.  We present results for two test cases using the proposed DyCore: an idealized heating/cooling test extending into the middle thermosphere and a perturbation experiment yielding nonhydrostatic baroclinic instability. The idealized heating/cooling test, which is compared to corresponding results from the hydrostatic Navy Global Environmental Model (NAVGEM), demonstrates that HEVI is more robust than traditional linear IMEX methods.  The baroclinic instability test shows that HEVI, when combined with a banded lower-upper (LU) direct solve, is efficient and allows a large timestep.  These numerical results suggest that our HEVI-enabled DyCore is a good candidate for the proposed thermosphere-ionosphere prediction system.This work was funded by the Office of Naval Research Marine Meteorology and Space Weather program.
Do Faults Localize as They Mature? Insight From 17 Continental Strike-slip Surface Rupturing Earthquakes (Mw > 6.1) Measured by Optical and Radar Pixel Tracking Data.
Authors: Milliner Chris , Avouac Jean-Philippe , Aati Saif , Dolan James , Hollingsworth James
Published: March 2024

As faults accumulate displacement, they are thought to mature from disorganized and distributed fracture networks to more simplified throughgoing fault structures with a more localized zone of inelastic strain. Understanding the degree of inelastic strain localization holds importance for seismic hazard, as smoother faults are thought to host faster rupture velocities and have different seismic shaking intensities from ruptures along rougher, less mature faults. However, quantifying this evolutionary process of strain localization along major fault systems has been difficult due to a lack of near-field coseismic measurements. Here we test if such an evolutionary process exists by measuring the near-field surface deformation pattern of 17 large (6.0 < Mw < 7.9) continental strike-slip surface ruptures. To do this we use a range of geodetic imaging techniques including, a new 3D optical pixel tracking method, and pixel tracking of radar amplitude data acquired by satellite and UAVSAR platforms. With these geodetic imaging data we measure the total coseismic offset across the surface rupture and difference them from the displacements recorded by field surveys, which we assume captures the on-fault, discrete component of deformation. This differencing allows us to obtain an average magnitude of off-fault deformation for each surface rupturing event, which we compare to a number of known source parameters to test the notion of progressive fault localization. Our results show that progressively smaller amounts of off-fault strain occur along fault systems with higher cumulative displacements, supporting the notion that faults systems localize as they mature. We also find strong correlations of off-fault deformation with the long-term fault slip-rate and the geometrical complexity of the mapped surface rupture, and a moderate correlation with rupture velocity. However, we find a weak-no correlation of off-fault deformation with the fault initiation age and the moment-scaled radiated energy. We also present comparisons of off-fault strain with other known seismic source parameters.
Satellite-based water surface slope in small mountain river
Authors: Lyu Haoyang , Tian Fuqiang
Published: March 2024

Satellite altimetry has emerged as a key alternative for inland water level measurement in addition to ground observations. Water surface slope (WSS) is one of the basic parameters of river morphology for discharge calculation. Estimation of WSS can also avoid systematic bias in satellite water levels relative to gauged data. A range of satellite data products are available to provide accurate river water level measurements and estimates of river WSS on a worldwide scale. Nonetheless, satellite-based observation of river water surface remains challenging in small rivers, such as the mountainous river reaches with narrow water surfaces. In this study, we examined the accuracy of the ICESat-2 ATL03 photon height data in estimating WSS over the mountainous river reach of Yongding River flowing across Hebei Province and Beijing City in northern China. With minimum along-track sampling interval of 0.7m, the ICESat-2 ATL03 data provided reliable estimation of WSS over narrow river reaches which are 50 to 100m wide. Satellite virtual stations were located mainly with a histogram-based statistical method, seeking for photon height that corresponds to the peak frequency. The twelve groups of satellite virtual stations chosen for river WSS estimation finally show an overall correlation coefficient of 0.96 in validation. Relative error of WSS estimation ranges from 0.13% to 14.51%. Findings of this study provide further implications for satellite-based river water surface measurement in small mountain river basins that lack of ground observation conditions, bringing in reliable estimation of key hydrological parameters based on satellite observation.
Assessment of Surface Water Dynamics between 1984-2021 in Madhya Pradesh, Central India, using Remotely Sensed Dataset
Authors: Swarnkar Somil , Surjibhai Asari Sushma , Nath Roshan , Singh Shobhit , Patra Biswajit
Published: March 2024

The measurement of surface water bodies plays a vital role in assessing the magnitude of floods and droughts despite their relatively little contribution to the overall hydrosphere on Earth's surface. The distribution and accessibility of water resources have been greatly impacted by global climate change and unsustainable human activities. These factors have resulted in heightened strain on surface water supplies, causing shortages that hinder both human consumption and socioeconomic progress. Therefore, the mapping and identification of surface water reserves are essential for achieving optimal utilization and sustainable management. Madhya Pradesh, henceforth referred to as MP, possesses a highly diverse range of geographical features within the Central Indian area. According to prior research, a total of thirty-six out of fifty-one districts within the state of Madhya Pradesh have seen significant hydrological drought conditions in recent years, mostly attributed to the scarcity of surface water resources. Despite the challenges faced in the MP area, there remains a lack of sufficient understanding of the long-term and seasonal variations in surface water dynamics within districts, as well as the overall availability and accessibility of surface water resources. Field-based observations of surface water bodies in regions with vast expanses, such as Madhya Pradesh (MP), pose considerable obstacles. However, the comprehension of spatiotemporal fluctuations in surface water can be enhanced with the utilization of remote sensing datasets for observations. Hence, to gain an understanding of the long-term fluctuations in surface water patterns in different regions of Madhya Pradesh, India, over a span of 38 years, we employed a publicly accessible global surface water dataset provided by the Joint Research Centre (JRC) of the European Commission. This dataset covers the time period from 1984 to 2021. Based on the results of our investigation, it is apparent that a disparity exists in the per capita accessibility of permanent water resources in the majority of MP districts, notably during periods of low precipitation, as well as in the per capita availability of seasonal water resources, particularly during months characterized by high levels of rainfall. While the monsoon period generally results in increased surface water availability, the Bundelkhand and Malwa Plateau regions experience severe shortages of surface water during dry periods, which, therefore, leads to the over-exploitation of groundwater resources. The implications of these findings are significant for the management of freshwater bodies in the Madhya Pradesh area, particularly in light of their depletion caused by climate change and human activities. Furthermore, these findings have broader implications for promoting sustainable development in the region.
Substantial increase in daytime-nighttime compound heat waves and associated population exposure in China 
Authors: Xie Wenxin
Published: March 2024

Daytime-nighttime compound heat waves (HWs) (i.e. concurrent occurrence of HWs both in daytime and nighttime) were documented to amplify the damages of high temperatures during daytime or nighttime. Nevertheless, the future change in compound HWs remains an open issue. This research presents the projected changes in compound HWs and associated population exposure in China under the shared socioeconomic pathway (SSP)2-4.5 and SSP5-8.5 scenarios based on the Coupled Model Intercomparison Project phase 6 simulations. The results generally indicate an aggravated risk of compound HWs in China in the future under warmer scenarios. Compound HWs in China are projected to increase significantly toward the end of the 21st century, with larger increase under SSP5-8.5 than that under SSP2-4.5. The greatest changes occur in northwestern China and southern China. Compared with the daytime HWs (i.e. occurring only in daytime) or nighttime HWs (i.e. occurring only in nighttime), the projected increase in compound HWs is the greatest. Accordingly, the proportion of compound HWs to the total HW events tends to increase and that of daytime HWs tends to decrease toward the end of the 21st century. Due to substantial increases in compound HWs, the population exposure to compound HWs will increase significantly across the entire country. The projected increase of nationally averaged population exposure is 12.2-fold (7.9-fold) of the current in the mid-century (2046–2065) and further enhances to 16.3-fold (12.4-fold) in the end-century (2081–2100) under SSP5-8.5 (SSP2-4.5). The largest increases are distributed in western China and southern China. These findings raise the necessity and urgency for policy-makers and the public to develop measurements to address compound HW risks.
Superionic Iron Hydride originated Ultra-low Velocity Zones at Earth’s Core Mantle Boundary
Authors: Zhang Yu , Wang Wenzhong , Wu Zhongqing
Published: March 2024

The origins of ultra-low velocity zones (ULVZs) detected at Earth’s core-mantle boundary, potentially linked to large low shear velocity provinces (LLSVPs), have been a subject of ongoing debate. Recent experiments have demonstrated the formation of iron hydride through a water-iron reaction under lowermost-mantle conditions; however, the stability of this compound has been inadequately constrained. By integrating first-principles molecular dynamic simulations with a machine learning approach, we have determined the stability and elastic properties of iron hydride under core-mantle boundary conditions.Our results reveal that iron hydride is a stable superionic phase, in which hydrogen diffuses akin to a liquid while iron vibrates at lattice sites. Significantly, this phase exhibits markedly slower velocities and a higher density compared to the ambient mantle under lowermost-mantle conditions. The accumulation of iron hydride, through either water-iron reaction or the solidification of core material, provides a plausible explanation for seismic observations of ULVZs, particularly those associated with subduction. This work underscores the substantial role of water in generating seismic heterogeneities at the core-mantle boundary.
Estimating reliable Probable Maximum Precipitation at data-sparse locations 
Authors: Bhatt Jaya , Srinivas Vemavarapu Venkata
Published: March 2024

Flood estimates corresponding to probable maximum precipitation (PMP) are desirable for planning, designing and risk assessment of large hydraulic structures, such as spillways of large dams, whose failure may have catastrophic consequences on ecology, economy, and the environment. In practice, PMP estimates are obtained using hydrometeorological or/and statistical methods as per the recommendations of the World Meteorological Organization. In regions where data of hydrometeorological variables (e.g., precipitation, temperature, relative humidity) are limited or unavailable, practitioners often resort to various statistical methods which require only precipitation records to estimate PMP. Among statistical methods, the Hershfield method is widely used when records from several sites in a region are available whereas conventional probabilistic approach is preferred for at-site analysis. However, arriving at reliable PMP estimates at data-sparse locations is still a challenge. Thus, there is a growing need to improve the existing statistical methods and develop/explore alternate methods. Against this backdrop, this study proposes a new variant of Bethlahmy method, which is a non-parametric method, to facilitate the estimation of PMP at locations with sparse records of extreme precipitation.The proposed Bethlahmy variant involves (i) mapping of datapoints and corresponding ranks of target site’s annual maximum precipitation series to a non-dimensional space (NDS), (ii) using the mapped information to arrive at a surrogate estimate for PMP in the NDS, and (iii) mapping the surrogate estimate to PMP in the original space. The efficacy of the proposed Bethlahmy variant over various existing statistical techniques is demonstrated through Monte Carlo Simulation experiments and a case study on 37,872 stations from a global precipitation database. The existing techniques include the original Bethlahmy and Hershfield methods, conventional probabilistic approach, and relevant variant(s). Results revealed that the proposed Bethlahmy variant outperforms other methods/variants across samples varying in size and extreme precipitation characteristics, making it a promising statistical alternative for PMP estimation.
Future change of hydrological regulation function of glaciers in the cold region basins of western China 
Authors: Yang Jianping , He Qingshan
Published: March 2024

As a solid reservoir, glaciers play a significant role in regulating the variation of runoff abundance and dieback in the form of “peak-cutting and valley-filling”. The hydrological regulation function of glaciers is very important in cold regions, especially in the arid regions of Northwest China. The runoff estimation data from 2014 to 2100 were simulated by the VIC-CAS model in the cold region of western China. With perspectives of combinations of trend and fluctuation characteristics, glacier hydrological regulation index (Glacier R) was constructed based on the runoff variation coefficient method to analyze the stability of glacier runoff in 9 cold region basins of western China. The changes of the hydrological regulation function of glaciers in these basins are analyzed in detail during the historical period (1971–2010) and in the future to the end of the 21st century. The results show that: In the historical period and under the RCP2. 6 and RCP4. 5 scenarios, except for the Yangtze River basin, the decrease time node of glacier runoff in other basins of the Tibetan Plateau is 2020s, and that in the northwest inland basins is 2010s. In historical period and under the global emission scenarios of RCP2. 6 and RCP4. 5 to the end of the 21st century, although the glacier runoff in most of cold region basins in western China showed a decreasing trend, the fluctuation range decreased or had no obvious change, and the stability of glacier runoff increased or had no change. Overall, hydrological regulation function of glaciers is high in the northwest inland river basins, while function is low in the basins of the Qinghai-Tibet Plateau. Under the global emission scenarios of RCP2. 6 and RCP4. 5, to the end of the 21st century, the hydrological regulation function of glaciers showed a weakening trend in all cold region basins of western China, and the weakening was more significant in the inland river basins of Northwest China. Under the global emission scenario of RCP4. 5,the hydrological regulation function of glaciers in the Muzati River decreased by 25. 4%, and all the basins of the Qinghai-Tibet Plateau remained at a low level. With the perspective of decadal variation, the hydrological regulation function of glaciers in the cold region basins of western China was strong during the period of 1970s–2010s, especially in the 1980s and 2000s. Under the global emission scenarios of RCP2. 6 and RCP4. 5, the hydrological function of glaciers showed a weakening trend obviously in the future to the end of 21st century. The earliest time node in the cold region basins is 1970s, and the latest is 2020s.
Retrieving climatic and temporal information from the last glacial maximum using an invert glacier model
Authors: Lleshi Kejdi , Jouvet Guillaume , Herman Frédéric , Cook Samuel
Published: March 2024

Understanding past natural climate variations during the Quaternary period is crucial for understanding the ongoing climate change. Glaciation events during the Quaternary have left visible footprints in today's landscape, such as moraines and trimlines, that could be used to reconstruct paleo glacier extent. Reconstructed glacier extent offers great potential to retrieve paleo-climate information during the coldest episodes of the Quaternary by inverting a glacier evolution model. However, current inversion methods are computationally expensive and their forward model relies on simplified physics. Fundamentally, they all assume glaciers are in a stationary state, which is simplistic and fails to capture essential transient features linking climate to glacier response.Here, we develop a new Machine-Learning (ML)-based inversion technique that overcomes the previously-mentioned limitations to reconstruct the glacier equilibrium line altitude (ELA), a proxy for temperature and precipitation, during a glacial maximum from reconstructed glacier extent. Our forward model consists of  a deep-learning emulator that learns the physical processes of a glacier from climate forcing to the glacier response. This approach has the advantage of being computationally highly-efficient, as well as allowing for automatic (thanks to the automatic differentiation) inversion of reconstructed glacier extent to retrieve a realistic ELA field that informs us about paleoclimates.When applying our method to the Last Glacial Maximum in the European Alps, our reconstructed ELA fields show  a clear separation between the northern and southern Alps, with northern ELAs being considerably lower as shown in Fig 1. Our results are supported by the glacier footprints reconstructed from geomorphological observations in the northern Alps, which suggest the presence of large glacier lobes. In contrast, the glacial lobes in the southern Alps were noticeably smaller.Our method is applicable in any formerly glaciated areas, and therefore has a high potential for paleoclimate reconstruction of the Earth’s coldest episodes.Figure1. The resulting ELA field from inverting the ‘observed’ glacier footprint. There is a visible difference in the climate between the north and the south.
A method of dynamic diagnosis for regional drought degree
Authors: Zhao Ruxin , Sun Hongquan , Xing Lisong
Published: March 2024

In view of the difficulty in quantifying the severity of regional drought, this study proposes a method that can quantify and dynamically diagnose the severity of regional drought events, and consider the cumulative superposition effect of drought in the process of spatial and temporal development and evolution. Starting from the site drought index, the method firstly establishes a regional drought index to determine whether drought occurs in the study area in the same month; secondly, it constructs a two-dimensional Copula joint probability model by counting the cumulative duration and cumulative severity of droughts; and finally, it uses the percentile method to classify the joint probability of two-dimensional cumulative drought characteristics into four degree levels of regional drought: light, moderate, severe, and extreme. In the study, the SPEI drought index from 1961 to 2022 was used as the basic data, and the drought centers of China, such as North China Plain, Yangtze River Basin, and Yunnan Province, were selected as the case validation zones, and the results showed that this method can effectively identify the historical drought events in the study area and dynamically diagnose the development process of severe and extreme droughts therein. 
Fiber-optic gyroscopes with enhanced temperature adaptability for geophysical rotational sensing
Authors: Chen Yanjun , Zhu Lanxin , Wang Wenbo , Huang Huimin , Cao Xinyu , Li Zhengbin
Published: March 2024

Fiber-optic gyroscopes, as rotational motion sensors, have emerged as powerful candidates for rotational seismology and Earth rotation observation due to their portability and high sensitivity. However, the stability of fiber-optic gyroscopes is degraded by environmental temperature variation that optical fibers are sensitive to. For the suppression of effects of temperature variation, conventional methods include the device level and post-processing level. However, the former has additional device requirements and higher costs, while the latter has a degradation of compensation for a more general environment. In this abstract, we propose a suppression method at the device level. We find that the effect of thermally induced phase fluctuations is significantly lower in the high-frequency band compared to the low-frequency band. Therefore, by upconverting the operating point of the fiber-optic gyroscope at a high-order harmonic of eigenfrequency, the effect of thermally induced phase fluctuations on the output is greatly suppressed. This method is easy to operate without requiring any additional optical or electrical components. To validate this method, we have conducted a time-varying temperature variation experiment using a portable fiber-optic gyroscope equipped with a 20 km long and 0.3 m diameter fiber-optic coil. The implementation of this upconverted frequency modulation technology resulted in a 32-fold reduction in temperature sensitivity for the fiber-optic gyroscope. The results demonstrate that the proposed technology enhances the temperature adaptability of fiber-optic gyroscopes, which is a critical aspect in practical geophysical applications. At the same time, the self-noise is reduced from 3×10-8 rad/s/√Hz to 8×10-9 rad/s/√Hz, further improving its sensitivity to observe geophysical rotation signals. Seismic records will be presented to demonstrate its utility in rotational seismology.
Deglacial circulation changes in the Nordic Seas, a switchboard of changes in AMOC and 'Nordic Heat Pump' 
Authors: Sarnthein Michael , Blaser Patrick
Published: March 2024

Differences in salt content of North Atlantic surface waters drive variations in Nordic Seas' overturning circulation. These form a switchboard for changes in the oceanic heat transport to North European high latitudes, the 'Nordic Heat Pump', and for Atlantic Meridional Overturning Circulation (AMOC). We deduced changes in the Nordic Seas' overturning circulation during the peak last glacial and early deglacial from two high-resolution marine sediment cores with centennial-scale age resolution based on the technique of radiocarbon plateau tuning (22-15 cal. ka). Sediment data suggest that the salinity of surface water, advected from the North Atlantic, started to drop about 18 400 years ago. This drop accompanied a 3°C rise in temperature and a drop in ventilation and radiocarbon ventilation age of Denmark Strait Overflow waters feeding the AMOC. Also, it paralleled a massive rise in the radiocarbon reservoir age of surface waters up to 2000 yr and an abrupt breakdown of Nordic Seas' deep-water convection off Norway. Accordingly, Atlantic waters were replaced by less saline polar waters, marking a breakdown of the Nordic Heat Pump and start of 'Heinrich Stadial 1' as reflected by a coeval cooling documented on top of the Greenland ice sheet, lasting until ~15.1 cal. ka.   
Comparison between non orographic gravity wave drag parameterizations used in QBOi models and Strateole2 constant level balloons                 
Authors: Rani Raj , Lott François , McLandress Charles , Podglagen Aurélien , Bushell Andrew , Bramberger Martina , Lee Hyun-Kyu , Alexander M. Joan , Anstey James , Chun Hye-Yeong , Hertzog Albert , Legras Bernard , Manzini Elisa , Osprey Scott , Plougonven Riwal , Scinocca John , Serrano Javier , Serva Federico , Stockdale Tim , Versick Stefan ,   Strateole 2 and QBOi contributors
Published: March 2024

Gravity Waves (GWs) parameterizations from 14 General Circulation Models (GCMs) participating to the Quasi-Biennial Oscillation initiative (QBOi) are directly compared to Strateole-2 balloon observations made in the lower tropical stratosphere from November 2019 to February 2020 (phase 1) and from October 2021 and January 2022 (phase 2). The parameterizations span the 3 leading edge techniques used in GCMs to represent subgrid scale non-orographic GWs, the two globally spectral techniques developed by Hines (1997) and Warner and McIntyre (1999) respectively and the "multiwaves" approaches following Lindzen (1981). The input meteorological fields necessary to run the parameterizations offline are extracted from the ERA5 reanalysis and correspond to the instantaneous meteorological conditions found underneath the balloons.  In general, the amplitudes are in fair agreement between measurements of the momentum fluxes due to waves with periods less than 1 hr and the parameterizations. The correlation of the daily values between the observations and the results of the parameterization can be around 0.4, which is statistically significant elevated considering that we analyse around 1200 days of data and quite good considering that the parameterizations have not been tuned: the schemes used are just the standard ones that help producing a Quasi-Biennial Oscillation (QBO) in the corresponding model. These correlations nevertheless vary considerably between schemes and depend little on their formulation (globally spectral versus multiwaves for instance). We therefore attribute this agreement to dynamical filtering, which all schemes take good care of, whereas only a few relate gravity waves to their sources. Except for one parameterization, significant correlations are mostly found for eastward propagating waves, which may be due to the fact that during both Strateole 2 phases the QBO phase is easterly at the altitude of the balloon flights. On the other hand, statistical properties, like pdf of momentum fluxes seem better represented in spectral schemes with constant sources than in schemes ("spectral" or "multiwaves") that relate GWs to their convective sources.
Recent Greenland warming in early summer and its link to atmospheric blocking trends in the Northern Atlantic sector
Authors: Filippucci Michele , Bordoni Simona
Published: March 2024

In recent decades, a more prominent negative phase of summer NAO has been observed (Hanna et al. 2015). While evident in observations, this signal does not emerge in model projections of future climate. Therefore, the attribution of the observed trend to internal variability or to anthropogenic forcing is a topic of growing debate. Improved understanding of the recent NAO shift is urgent, given its several impacts on the climate system, such as temperature extremes at high latitudes and a pronounced acceleration of Greenland ice melting. In this work, we try to achieve a better understanding of the concurrent causes of the observed trend by analyzing Greenland atmospheric blocking, a synoptic phenomenon that strongly anticorrelates with NAO. We choose to focus our analysis on blocking events resulting from the cyclonic breaking of Rossby waves in the Northern Atlantic. For these purposes, we develop an original Lagrangian tracking algorithm for atmospheric blocking detection based on the geopotential height gradient reversal (Davini et al. 2012), which allows us to compute the blocking events number, area, persistence and average displacement. Results confirm how the occurence of Greenland atmospheric blocking is increasing. The frequency trend is attributed to an increased number of blocking events in summer, rather than an increased persistence, suggesting a change in the triggering mechanism. In addition, a diminuished number of blocking events in spring emerges, together with a decreased spring blocking persistence. Moreover, we apply a zonal-blocked flow decomposition to investigate to what extent the emergent mean summer geopotential height anomaly can be attributed to blocking or to mean state differences. The decomposition highlights how the anomaly is strong even in the days not interested by atmospheric blocking and how the increased frequency is rather acting as a positive feedback mechanism of the negative NAO phase.
Assessing wave energy as extreme events propagate near the coast
Authors: Matar Reine , Abcha Nizar , Turki Emma-Imen , Lecoq Nicolas
Published: March 2024

KeywordsPhysical modeling; Wave flume; Extreme waves; Wavelet transform; Machine Learning; MLP modelPhysical modeling, spectral analysis, and artificial intelligence techniques were used to study extreme wave behavior and its evolution in shallow waters. A series of physical tests were conducted in a laboratory wave flume using different wave spectra, including JONSWAP (γ = 7), JONSWAP (γ = 3.3), and Pierson-Moskowitz, varying within a broad range of wave amplitudes. The dispersive focusing technique was used to generate these spectral waves. To account for the varying duration of extreme events, one, three, six, and nine wave trains were generated. A total of fifty-one wave gauges, located between 4 m and 14 m from the wave generator, provided comprehensive monitoring of the wave characteristics and their propagation along the wave flume [1]. The analysis incorporates wavelet transform to identify frequency components and their assigned energy using the Maximal Overlap Discrete Wavelet Transform (MODWT) method. The energy of the dominant frequency components, d5 and d4, which represent the peak frequency (fp = 0.75 Hz) and its first harmonic (2fp = 1.5 Hz), respectively, has significantly decreased. In contrast, the energy of the remaining components has increased. By investigating the energy of each frequency component along the wave flume, potential correlations between the dissipation of dominant frequency components and zones of higher energy dissipation are explored. Moreover, using the Multilayer Perceptron (MLP) machine learning algorithm [2], the study confirmed the repeatability of our findings regarding the energy of the frequency components with an accuracy of 98%. This study demonstrates the effectiveness of the MLP algorithm in improving wave prediction using field experimental data.[1] Zhang, J., Benoit, M., Kimmoun, O., Chabchoub, A., & Hsu, H. C. (2019). Statistics of extreme waves in coastal waters: large scale experiments and advanced numerical simulations. Fluids, 4(2), 99.[2] Abroug, I., Matar, R., & Abcha, N. (2022). Spatial Evolution of Skewness and Kurtosis of Unidirectional Extreme Waves Propagating over a Sloping Beach. Journal of Marine Science and Engineering, 10(10), 1475.
A differentiable, physics-informed ecosystem modeling: investigating the photosynthetic capacity parameterization 
Authors: Aboelyazeed Doaa , Xu Chonggang , M. Hoffman Forrest , Jones Alex W. , Rackauckas Chris , Lawson Kathryn , Liu Jiangtao , Gu Lianhong , Shen Chaopeng
Published: March 2024

Different parameters serve as key determinants in simulating the photosynthesis process and representing photosynthetic traits as the net photosynthetic rates and the stomatal conductance. Previous methods of calibrating these photosynthetic parameters at individual sites encountered challenges in harnessing large-scale datasets and encountered issues such as overfitting or non-uniqueness of parameters. Moreover, they often relied solely on plant functional types (PFTs) to capture the inherent variability in these parameters or used other empirical values. These ignored the impact of acclimation of these parameters to the prevalent environmental conditions. Here, we utilized a recently developed differentiable ecosystem model—a hybrid, physics-informed machine learning system that can digest large global dataset and output interpretable intermediate variables —to do parameter inversion using PFT along with various environmental factors, including air temperature, radiation, and vapor pressure deficit, both over short-term and long-term durations. We mainly focused on the photosynthetic capacity related parameters represented in the maximum carboxylation rate standardized to 25 ॰C  (Vc,max25), the stomatal conductance parameters, and some temperature response function parameters. To achieve this, we employed different neural network (NN) configurations to explore the dependence of these sets of parameters on environmental conditions while employing a loss function that uses the observations of both net photosynthetic rates (An) and stomatal conductance (gs). Using this framework we were able to have a better understanding of the correlation between physical parameters and the surrounding environment for different PFTs. 
Competitive methane bubble growth in aquatic muds
Authors: Zhou Xiongjie , Katsman Regina
Published: March 2024

Methane (CH4) bubbles developed in shallow aquatic muds present a significant environmental risk. Macroscopic CH4 gas content in the muds is accommodated in discrete bubbles that grow from below the pore scale size to the maximum size defined by muddy sediment mechanical properties. The bubbles force out the water within the pores and distort the structure of the muddy sediment by moving the grains apart at their growth above the pore scale. However, the interaction between growing bubbles was not understood. This study uses a mechanical/reaction-transport numerical model to simulate the interaction of competitive CH4 bubbles paired with fracture-driven growth of varying initial sizes in aquatic muds. It reveals that mechanical and solute transport dynamics play a crucial role at different stages of bubble growth, particularly hindering the development of smaller bubble growth in competition. The stress from the larger bubble impacts the inner pressure and diffusive CH4 flux to the smaller bubble, slowing its initial growth (at t < 40 s). Additionally, the larger bubble later diverts CH4 from the smaller one, further inhibiting its growth expansion. This interaction may cause more horizontally oriented smaller bubbles and significant deformations in the larger bubble, especially as the distance between the bubble pair decreases. Such competitive bubble growth may explain the bubble size distributions observed in lab experiments and in situ, promoting CH4 retention in muddy sediments and the formation of gas domes, which are precursors to pockmarks that can cause abrupt gas releases to the water and potentially the atmosphere. The study provides a foundation for upscaling to different models of gassy muddy sediment acoustic characteristics and models of gas retention evolution, while maintaining single bubble growth metrics. It contributes to better evaluating and potentially reducing long-persisting uncertainties around CH4 emissions from shallow aquatic sediments.
Effect of intermittent drainage on the emission of two greenhouse gases (CO2 and CH4) from three paddies in South Korea
Authors: Hyun Seunghun , Hwang Wonjae , Park Minseok , An Youn-Joo , Hong Sunhee , Jeong Seung-Woo
Published: March 2024

In this field pot study, effect of irrigation practice (continuous flooding (CF) and intermittent drainage (ID) treatment) on greenhouse gas (GHGs, CO2 and CH4) emission was determined from three Korean paddies (BG, MG, and JS series), varying soil properties such as soil texture, labile carbon, and mineral types.  Emission of GHGs was evidently influenced by irrigation practices, to a different extent, depending on paddy’s redox response to flooding events.  The Eh decline upon flooding was slower in JS pot, where pore-water concentration of ferric and sulfate ions is the highest (~ up to 3-fold) among three paddies.  MG pot was 2- to 3-fold percolative than others and the Eh drop during flooding period was the smallest (remaining above -50 mV) among three pots.  By adopting ID, CH4 emission (t CO2-eq ha-1 yr-1) was reduced in a wide range by 5.6 for JS pot, 2.08 for BG pot, and 0.29 for MG pot relative to CF, whereas CO2 emissions (t CO2-eq ha-1 yr-1) was increased by 1.25 for JS pot, 1.07 for BG pot, and 0.48 for MG pot due to the enhanced carbon oxidation upon drainage.  Grain yield and aboveground biomass production from ID were no less than those from CF (p < 0.05).  Consequently, benefit of global warming potential (S GWP) by ID varied as in order of JS (37%) > BG (14%) > MG (~0 %) pots, and negligible effect observed for MG pot was due to the equivalent trade-off between CO2 and CH4. Our findings imply that that the efficacy of drainage on GHG mitigation depends on the redox response of paddies.KeywordClimate Change, Greenhouse gas, Paddy, Intermittent drainage AcknowledgementThis research was in part supported by the Korea Environment Industry & Technology Institute (KEITI), funded by Korea Ministry of Environment (MOE) (No. 2022002450002 (RS-2022-KE002074)) and in part supported by Korea University Grant.
Overwintering and migration of sea turtles in Jeju Island of Korea: lessons from “SEAturtle” PICES special research project (2019-2023) 
Authors: Kim Taewon , Jang Soojin , Kim Mi-Yeon , Kim Byung-Yeob , Jo Kyungsik , Jang Sookjin , Im Jibin , Balazs George , Nishizawa Hideaki , Ka Kan NG Connie , Shillinger George , María Early Capistrán Michelle
Published: March 2024

PICES special research project “SEAturtle” launched in 2019 to understand the ecology of sea turtles around Jeju Island in relation to environmental stressors. Though COVID 19 had interrupted the project, we had quite a successful outcome over the last 5 years. Until now (June 15, 2023), a total of 16 iridium transmitters were deployed on sea turtles (14 on green sea turtles and 2 on loggerhead sea turtles). Among them, we received the signals successfully from 15 sea turtles. We found that quite a proportion of green sea turtles released in Jeju Island (N = 4 out of 12, approx. 40%) overwintered nearby even in the cold sea where the temperature dropped to 15 °C. The diving duration increased to approx. 6 hrs with decreasing temperature. Most of migrating green sea turtles (N = 4) traveled toward southern Japan which suggests a strong link to the population in Japan. Our population genetics result on green sea turtles stranded suggests that a subunit of Jeju population also have an affinity to Japan population. On the other hand, one of our loggerhead sea turtles moved westward but the other moved southward from Jeju Island, suggesting that they may also have connectivity to both Japan and China. Our populations genetics and stable isotope analysis on the commensal barnacles support this. We also have actively worked on the threat of plastics on Jeju populations and found that derelict recreational fishing gears might cause more serious problems than commercial derelict fishing gears. Microplastics are other threats to them too. To conserve the population of sea turtles in Jeju Island, we need further extensive research and should keep up international cooperation.
Photonic Seismology: A New Decade of Distributed Acoustic Sensing in Geophysics from 2012 to 2022
Authors: Cheng Feng , Zhao Ke , Zhao Longfeng , Ajo-Franklin Jonathan
Published: March 2024

This work delivers an in-depth bibliometric analysis of Distributed Acoustic Sensing (DAS) research within the realm of geophysics, covering the period from 2012 to 2022 and drawing on data from the Web of Science. By employing bibliographic and structured network analysis methods, including the use of VOSviewer®, the study highlights the most influential scholars, leading institutions, and pivotal research contributions that have significantly shaped the field of DAS in geophysics. The research delves into key collaborative dynamics, unraveling them through co-authorship network analysis, and delves into thematic developments and trajectories via comprehensive co-citation and keyword co-occurrence network analyses. These analyses elucidate the most robust and prominent areas within DAS research. A critical insight gained from this study is the rise of 'Photonic Seismology' as an emerging interdisciplinary domain, exemplifying the fusion of photonic sensing techniques with seismic science. The paper also discuss certain limitations inherent in the study, and concludes with implications for future research.
Cropland Microplastics in Xinjiang: Unveiling Distribution and Impact of Mulching Film Residues
Authors: Zhang Qingling , Zhang Shan , Dong Wuzhou , Wang Zhipan , Mo Zewen
Published: March 2024

Microplastics, ubiquitous environmental pollutants, pose a significant threat to agricultural ecosystems and food safety. Xinjiang, a critical dryland agricultural region in China, faces a pressing issue with microplastic accumulation due to extensive use of mulching film. This study addresses this challenge by combining feild investigation, lab analysis, and remote sensing observations:
Developing an improved, batch-processed soil microplastics extraction method, optimizing cost and time.
Extracting and analyzing microplastics from typical Xinjiang cropland soil, revealing their distribution patterns and influencing factors.
Establishing a model linking microplastic abundance to cumulative mulching film years, providing a predictive tool.
Combining the model with remote sensing data to unveil the regional distribution of microplastics across Xinjiang croplands.
Our findings provide:
A deeper understanding of microplastic pollution dynamics in mulching film-based agriculture.
A robust method for assessing and predicting microplastic contamination in croplands.
Valuable data for informing mitigation strategies and policy decisions.
This study paves the way for effective microplastic management and for examining their environmental impacts in Xinjiang and beyond, safeguarding agricultural productivity and environmental health. Future study efforts are encouraged to examine local and remote impacts of soil microplastics in Xinjiang and beyond.
Impacts of global change drivers on terrestrial methane emission and uptake
Authors: Zhu Tingting , Zhou Yanlian , Ju Weimin , Yan Ran , Xie Rui , Mao Yu
Published: March 2024

 Methane (CH4) is the second largest greenhouse gas and affects global climate change. In turn, global changes strongly affect CH4 fluxes from the terrestrial biosphere to the atmosphere. However, it is unclear how CH4 fluxes are affected by warming (W), precipitation patterns (P), elevated carbon dioxide (eCO2), and nitrogen (N) addition. Here, we synthesized terrestrial CH4 fluxes data from 1,165 observations performed under changes in W, P, eCO2, and N across different vegetation types over the globe. Results showed N addition significantly reduced CH4 emission and uptake across upland ecosystems (-31% and -14%, P0.05) and wetlands (24%, P