bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancing Radar-Based Ensemble Nowcasting with CSGD: A UK Study
Authors: Lin Hung-Ming , Wang Li-Pen
Published: March 2024

Probabilistic radar-based precipitation nowcasting is increasingly vital for real-time hydrological applications because not only it produces timely rainfall input but also the informative ensemble nowcasts may facilitate decision making. There are two primary sources uncertainty while using radar-based nowcasts for hydrological applications. The first one lies in nowcasting algorithm itself; for example, inaccurately predicted rainfall magnitudes and rainfield advection displacement errors, both exacerbated as the lead time increases. The second one is the ‘measurement’ error. There is a notable discrepancy between radar-derived precipitation estimates and measurements from rain gauges, underscoring the inherent uncertainties, including systematic and random errors, in radar data. This discrepancy necessitates aligning indirect radar measurements with actual ground-level precipitation for practical hydrological applications and analyses.In this study, we focus on tackling the ‘measurement’ uncertainty, such that the applicability of ensemble nowcasts to hydrological practices can be improved. In the proposed method, rain gauge observations are treated as the ground truth. The Censored and Shifted Gamma Distribution (CSGD) model is then constructed using these gauge data and the co-located radar rainfall estimates. The use of CSGD model lies in its ability to not only condition actual rainfall estimates on radar data values but also account for precipitation climatology at gauge locations. Based on the CSGD parameters at know locations, we can further interpolate parameters for any locations within our study domain. We then employed the STEPS (Short-Term Ensemble Prediction System) to generate radar-based ensemble nowcasts, which are then adjusted at each radar pixel locations using CSGD model with the corresponding parameters. This leads to CSGD-enhanced ensemble nowcasts.The United Kingdom, with its comprehensive weather data, served as the experimental area for this study. The 1-km UK C-band radar composite from the Met Office Nimrod System and the Met Office Integrated Data Archive System (MIDAS) gauge data were utilised. By aggregating these datasets into hourly scales, climatological and conditional CSGD parameters from 2015 to 2020 were estimated. The evaluation involved two stage. Initially, about 10% of rain gauges were excluded from the CSGD model fitting, with parameters estimated via Kriging interpolation. This is to ensure the quality of interpolated CSGD parameters. Then, a total of 30 storm events from 2021 to 2023 were selected to test the proposed method. Preliminary results show that the CSGD-enhanced ensemble nowcasts show a higher agreement with rain gauge observations as compared to the original nowcasts.The proposed method is of great practical potential to provide not only timely but also enhanced precipitation nowcasts to critical hydrological applications, such as landslide or flooding warnings.
Daily growth rate variation in Tridacna shells as a record of tropical cyclones in the South China Sea: Palaeoecological implications
Authors: Zhao Nanyu , Yan Hong , Luo Fan , Yang Yuanjian , Liu Shan , Zhou Pengchao , Liu Chengcheng , Dodson John
Published: March 2024

Tropical cyclones (TC) are one of the most destructive weather phenomena on Earth. However, the short duration of instrumental weather records means that little is known of the frequency of TCs through geological time. Here we analyse a Tridacna squamosa shell with a life span about 6 years (from 12 May 2013 to 18 December 2018) from the northern South China Sea. Studies of daily growth rate variations (DGRV) were correlated with coeval environmental changes to develop a proxy for TC. Results reveal that the frequency and variation of extreme DGRV were conspicuously different between the typhoon-affected season (July to October) and the relatively stable growth season (March to June). During the typhoon-affected season, the frequency of sudden onset of decreased sea surface temperature, attenuated solar radiation and heavy precipitation can result in more days for extreme decreases of DGRV. On interannual timescale, the frequency of extreme DGRV was significantly correlated with TC influence days. Our findings indicate that the frequency of extreme DGRV profile in Tridacna squamosa shells has potential to be a novel recorder for past TC activity. We conclude that fossil shells in different geological eras offer the potential to extend modern instrumental datasets and provide opportunities for investigating TC activity in response to past and future global change.
Seasonality in northern South China Sea during the late Holocene
Authors: Liu Chengcheng , Yan Hong , Zhou Pengchao , Wang Guozhen , Zhao Nanyu , Han Tao
Published: March 2024

The annual temperature cycle is an important component of the Earth’s climate system. Here, the multiple snapshots sea surface temperature (SST) seasonality during past ~1600 years of northern South China Sea were reconstructed using monthly resolved δ18O and Sr/Ca profiles of fossil Tridacna and  coral skeletons. The results showed SST seasonality in northern SCS was contrary to temperature of China mainland and West Pacific Warm Pool, with a large seasonality during cold period (Little Ice Age, Dark Ages Cold period) and a small seasonality during warm period (Medieval Climate Anomaly). During Little Ice Age and Dark Ages Cold periods, strong East Asia Winter Monsoon (EAWM) and La Niña-like state of tropical Pacific Ocean promote a cold winter, and thus induce a large SST seasonality of northern SCS. During the Medieval Climate Anomaly, weak East Asia Winter Monsoon (EAWM) and El Niño-like state of tropical Pacific Ocean promote a warm winter, and thus induce a small SST seasonality of northern SCS.
Stable isotopes and palaeo-hydrological implications of Tunisian laminar calcretes during the late Pliocene - early Pleistocene
Authors: Jarraya Farah , Mauz Barbara , Rogerson Mike , Kallel Nejib , Elmejdoub Nouredidne , Sghari Abdeljalil
Published: March 2024

During the late Pliocene-early Pleistocene Tunisian calcretes were formed in a soil environment. Fabrics at the macro and micro scale show that these deposits are similar to rhizogenic modern analogue systems forming in Spain. We infer that a similar climate prevailed in Tunisia in the past, specifically winter-season rainfall and a dry summer with annual rainfall close to 430 mm/year in the center of Tunisia. Here, we provide further constraints on the climate under which the Tunisian calcrete formed by looking at vegetation structure, water advection and amount of seasonal rainfall.To investigate (1) the palaeo-vegetation type(s) if they are C3 or C4 plants and (2) the source(s) of meteoric water of Tunisian calcretes during that era, stable isotopes of C and O were analysed in 25 samples taken from 5 horizontal laminar calcretes cores, from 3 sites: North (N36º.43.713; E10º.06.681’), Center (N35º.07.077’; E10º.14.545’), South (N33º.28.898’; E10º.23.602’). Results are expressed relative to the VPDB reference.In the North, the δ18O samples show values varying from – 4.78 ‰ to -6.91 ‰. Likewise, central site cores are characterised by δ18O values ranging from -5.32 ‰ to -6.97 ‰. In contrast, the δ18O values from the South are more depleted (-8.82 ‰ to -7.20 ‰). Concerning the carbon isotope results, both central and southern sites show similarly enriched δ13C values with an average of -6 ‰, while the North site shows more depleted values (-11.3 ‰ to -9.6 ‰). The δ18O values are similar to those determined in the last deglaciation/early Holocene speleothem carbonates from caves in the Tunisian Atlas Mountains, indicating a North Atlantic source. The north-to-south difference in both isotope systems reveals a decoupling between precipitation δ18O and vegetation effects. The southern site shows more depleted water isotopes (a consequence of internal water recycling effects) and more enriched δ13C, consistent with C4 vegetation and/or lower soil respiration. The central site shows low water recycling, but southern-like dryland vegetation. The northern site shows low water recycling and C3 vegetation and/ or higher soil respiration. Consequently, although there is enhanced humidity in all three sites, the sites do not record the same amount of rainfall and the same response of the landscape to form calcretes.
A small coil transient electromagnetic system for quick subsurface mapping 
Authors: Maurya Pradip , Auken Esben , Bording Thue
Published: March 2024

Transient Electromagnetic (TEM) methods are widely used in near-surface geophysical exploration. Traditional ground-based TEM systems utilize large transmitter loops (25x25 to 50x50 m²) to investigate depths between 200 and 300 meters, yielding 15-20 soundings per day. To enhance efficiency in shallower investigations (0 - 100 m), we introduce a compact TEM system with a small coil setup for rapid deployment and mobility, increasing data collection rates along extensive transects. The novel system comprises a 3x3 m transmitter loop with two turns and an equivalently sized offset receiver loop with four turns, separated by 10 m to minimize coil coupling and ensure unbiased signals. Operating as a single-moment setup, it achieves a peak current of 5 Amp or 10 Amp, turning off in approximately 7 µs. Unbiased measurement begins at 10 µs post turn-off, extending to a late gate of 3 ms. Both transmitter and receiver are integrated into a portable unit powered by lightweight lithium-ion batteries. A dedicated mobile application for Android and iOS devices controls the system, facilitating real-time monitoring of data curves and system parameters like current and temperature.With this system, two people can collect a 400 m profile in under 60 minutes, significantly faster than Electrical Resistivity Tomography (ERT) methods. The presentation will cover the system's layout, operational methodology, depth capabilities, and validation against the Danish National TEM Test Site. Comparative analyses will underscore its efficiency and effectiveness in aquifer layer mapping, offering a compelling alternative to traditional ground-based systems.
Forecasting the evolution of volcanic unrest
Authors: Ferrara Salvatore , Marzocchi Warner , Selva Jacopo , Sandri Laura
Published: March 2024

The management of volcanic unrest near densely inhabited areas requires collaboration between scientists, who are required to provide near real-time information, and decision makers. The ambiguity of pre-eruptive patterns and the inaccessibility and the complexity of the system lead to large uncertainties, suggesting the preference for probabilistic approaches over deterministic ones. The divergence of scientists' opinions regarding pre-eruptive phenomena can lead to extreme confusion, which inevitably translates into the difficulty of reaching an agreement for the optimal management of an emergency. Expert elicitation is a procedure for extracting a collective opinion in a relatively short time despite the incomplete knowledge of the problem and is therefore an effective tool for managing forecasts during volcanic crises in near real-time. In this work we present the results of the latest elicitation sessions at the Campi Flegrei caldera, represented by a list of weighted parameters with their respective thresholds that define the anomalous values and their interpretation, to calibrate BET_EF eruption forecasting model. Our aim is to re-calibrate it using the most recent scientific evidence linked to the increase of the activity of Campi Flegrei which has been observed in the last few years, evaluating the probability that the mechanism underlying the current unrest is a rise of magma, and the probability that this could lead to an eruption. Finally, we demonstrate a practical application showing the variation of the probability of magmatic unrest and eruption as a function of the variation of the values of the monitoring parameters ​​obtained through the elicitation.
Development of artificial intelligence based computational pathology to assess the histopathological toxicity of antibiotics to marine mussels
Authors: Xu Jianzhou , Zhao Ruoxuan , Liu Ao , Li Liya , Li Shuimei , Wu Kaijie , Di Yanan
Published: March 2024

Antibiotics are emerging contaminants of concern worldwide, especially in coastal areas. However, no conclusion can confirm their ecotoxic effects based on popular employed biomarkers. Based on our previous exploration on the histopathological changes on marine model organism-marine mussels, convincing results indicated sulfamethoxazole (SMX) can induce tissue damage but the examination procedure was labor- and time-consuming. In this study, a systematic working flow of histopathological assessment was developed, including qualitative, semi-quantitative, quantitative and artificial intelligence (AI)-based quantitative methods, forming the computational pathology on functional tissues in marine mussels. The exposure of mussels to a serial concentration of SMX was conducted, gill and digestive gland of mussels were stained by H&E to perform the developed working flow. The results confirmed that SMX exposure indeed cause significant histopathological alterations in both tissues. The manual semi-quantitative, quantitative and AI-based quantitative indicators all showed a well dose-response relationship with SMX exposure. In particular, AI-based quantitative methods can identify and segment biological pathological images, and screen quantitative pathological indicators and significantly reduce the time-cost. This study confirmed the valuable application of quantitative and AI-based quantitative histopathological indicators in marine ecotoxicology, and promotes the study of computational pathology of marine organisms in emerging marine pollutants.
Degradation pathways and mechanisms of oilwell cement exposed to H2S under high temperatures
Authors: Zhang Liwei , Yin Yue , Mei kaiyuan , Cheng Xiaowei , Wang Yan , Wang Hanwen
Published: March 2024

The extraction of geothermal energy faces the hazard of H2S, a highly toxic and strongly corrosive gas. H2S exposure can lead to the failure of oilwell cement, decreased extraction efficiency, and even pose serious risks to operational personnels near the wellsite. High temperature is a prominent environmental feature in geothermal resource extraction. However, current research works primarily focus on the corrosion effects of H2S on cement at moderate to low temperatures. This study utilizes Class G oilwell cement to conduct corrosion experiments of cement by H2S under high temperature in a H2S-rich reaction vessel. The impact of H2S on the structure, chemical composition, and mechanical strength of oilwell cement is analyzed via SEM-EDS, XRD, nanoindentation tests, and unconfined compressive strength tests. The results indicate a reduction in compressive strength for cement samples corroded by H2S. The surface nano-hardness and elastic modulus of cement samples decrease while the internal values of nano-hardness and elastic modulus significantly increase. Under the corrosion of H2S, the structure of cement is characterized by a yellow and black surface layer and stratified cracks. The external surface of the cement exhibits a yellow color due to the formation of pyrite (FeS2), while internally, pyrrhotite (FeS) and gypsum (CaSO4.2H2O) are generated.
Recent advances in flint provenance studies in Israel developed by combining geochemical and statistical perspectives
Authors: Ben Dor Yoav , Finkel Meir , Sharon Gonen , Tirosh Ofir , Bar Oded , Ben-Yosef Erez
Published: March 2024

Provenance studies of flint artefacts provide important means for interpreting raw material procurement strategies, which testify to the level of expertise and environmental knowledge of prehistoric people. Due to its importance, different approaches and methods have been used in order to address this topic, which often makes it difficult to compare different studies. During the recent years we have been exploring the potential of bulk rock composition of flint measured using inductively coupled mass-spectrometry (ICP-MS) for provenance studies. Through the systematic sampling of flint from all across Israel (now archived at the Geological Survey of Israel, as part of the developing national flint collection) and the investigation of a large suite of trace elements, we have been developing a robust approach for determining the provenance of flint. By sampling several specimens from each locality and measuring a large array of elements, we additionally address the variability of compositional data in natural rock sources, and develop a statistical framework for evaluating the uncertainty involved in the provenancing of flint. These developments have been applied in recent case studies in key archaeological sites, and shed new light on the old question of flint provenance in prehistory.
The links between high heat producing granites and large-scale W-Sn deposits: insight from numerical modeling
Authors: Liu Xiang-Chong , Zhang De-Hui
Published: March 2024

The granites associated with large-scale W and Sn deposits generally have high concentrations of U, Th, and K, including but not limited to the Cornubian Batholith in Southwest England, the Krušné hory/Erzgebirge Batholith in Central Europe, the Sardinian Batholith in Italy, and the Gejiu Batholith and the Qianlishan granitic complex in South China. These granites can be classified as high heat producing (HHP) granites (>5 μW m-3) because of high radiogenic heat production. However, how long radiogenic heat can prolong the suprasolidus lifetime of magmas and whether radiogenic heat exerts an influence on later W and Sn mineralization is poorly understood.To answer these questions, finite element numerical modeling was established to link magma cooling by heat conduction with diffusion of W, Sn, and H2O from silicate melts to coexisting aqueous fluids before the solidus is reached. The magma size (vertical thickness of 4–5 km and horizontal length of 20 km) is constrained by the granites associated with large-scale W and Sn deposits. The modeling results suggest that the suprasolidus lifetimes of HHP magmas are positively correlated with the heat production and magma thickness and negatively correlated with the solidus temperatures and the thermal conductivity of host rocks. Average radiogenic heat of 5–10 μW m-3, together with decreased solidus temperatures due to magmatic differentiation and a moderate thermal conductivity of host rocks, can prolong the suprasolidus lifetime of HHP magmas by 49–427 ka (1 Ma = 1000 ka), corresponding to 11–85 % of the suprasolidus lifetime of equally sized magmas with normal radiogenic heat (2 μW m-3). From the available gravity modeling data, over half of the granites associated with large-scale W and Sn deposits are at least 1 km thicker than the values calculated from the empirical power–law equation, and the modeling results indicate that an increase of 500–1000 m in magma thickness prolongs the suprasolidus lifetimes of HHP magmas (5 μW m-3) by 50–74 %. During magma cooling before solidus is reached, the diffusion of W and Sn is at least several orders of magnitude slower than that of H2O in hydrous melts; thus, the equilibrium partitioning of these two metals between silicate melts and coexisting aqueous fluids is not reached, and the metal diffusion from melts is a rate-limiting step. The prolongation of the suprasolidus lifetimes by radiogenic heat and decreased solidus temperatures can allow extraction of 17–95 % more W and Sn from silicate melts before the solidus is reached and increase the possibility of producing W and Sn mineralization at later stages. Therefore, the coexistence of HHP granites and large-scale W and Sn deposits is not accidental.
Understanding and disentangling of flood generation mechanisms
Authors: Meresa Hadush , Griffin Adam , Kay Alison
Published: March 2024

Extreme rainfalls and floods have caused severe socio-economic and environmental losses in most parts of the world and are predicted to exacerbate due to the changing climate. Highly saturated soil, extreme rainfall, and heavy snowmelt are the most common flood triggers. However, the relative contributions of extreme, long rainfall, antecedent soil moisture, and snowmelt and how they are vary with time and change from catchment to catchment are not fully understood. This information is critical for a better understanding of flood generation mechanisms and can improve flood risk management plans and strategies. We examined precipitation, streamflow, and estimated anticipated soil moisture (anticipated precipitation index) from more than 146 hydrological stations across the UK. Our main objectives were: creating flood type classes according to hydrometeorological characteristics, identifying the contribution of independent variables (soil moisture, snow, rainfall) and understanding the spatial and temporal variability of mutual information.A simple empirical relationship between the peak flow and precipitation was used to estimate the anticipated precipitation index, used as a proxy for antecedent soil moisture. The relative importance of each variable and its respective flood-generating processes were identified using multilinear regression and decision tree approaches. Based on catchment average rainfall, gauged streamflow, and estimated anticipated soil moisture data across the UK, we confirm that most of peak flows are strongly associated with both the extreme rainfall and antecedent soil moisture conditions above the 90th percentile. There is a clear difference in flood magnitude and their respective generating mechanisms between regions, and regions with an expected decrease in anticipated soil moisture into the future were highly statistically correlated with a decrease in annual average peak flood magnitude. The role of extreme rainfall is the most dominant factor across the UK; however, seasonal total rainfall is not a strong influencing factor of peak floods in the southern UK. Extreme rainfall and peak floods are positively corrected with catchment drainage area. This linkage between drainage area and the most common flood generation mechanisms is crucial to quantifying the magnitude and level of flood risk in ungauged catchments.
Observations of destratification events in a highly stratified bay in the Ebro Delta
Authors: Peñas-Torramilans Raquel , Grifoll Manel , Espino Manuel , Fernández Margarita , Balsells F-Pedrera Marta , Chen Yang , Sospedra Joaquim , Sánchez-Arcilla Agustín
Published: March 2024

Coastal environments are regions characterized by complex hydrodynamics with high temporal variability in water circulation due to environmental drivers such as local wind, freshwater inflow, or tidal variations. This research investigates the hydrodynamics of destratification events in a highly stratified micro-tidal coastal estuary, such as is the Fangar Bay (Ebro Delta, NW Mediterranean). The bay's hydrodynamics are mainly driven by local wind events and modulated by water column stratification, which is dominant and controlled by freshwater inputs and oscillatory motions. The study here presented is based on the time-series analysis of two ADV (Acoustic Doppler Velocimeter), combined with temperature and salinity profiles, deployed within the bay during the Spring of 2023. Results show a clear destratification of the water column after intense wind episodes, mostly from the northwest, which alter the response of the velocity field and re-distribute the constituents of the water column through mixing and dispersion. The high-frequency analysis of the recorded velocities suggests a differential pattern between upper (fresher) and lower (saline) layers of the water column, with significant implications for aquaculture and water quality.Keywords: destratification, estuary, hydrodynamics, mixing, measurementsFunding: This work has been funded by the R+D+I project ECO-BAYS (PID2020-115924RB-I00) financed by MCIN/AEI/10.13039/501100011033.  Acknowledgements: To project REST-COAST (H2020-101037097-REST-COAST) from the European Union’s Horizon 2020 program.
Effects of cryospheric hydrological processes on future flood inundation and the subsequent socioeconomic exposures in Central Asia
Authors: Wang Ning , Sun Fubao , Wang Hong , Liu Wenbin
Published: March 2024

Floods and their subsequent socioeconomic exposures are increasing in most parts of the world due to global warming. However, less attention is given in the arid Central Asia (CA), in which floods usually occur in data-scarce high-mountainous regions with complex cryospheric hydrological processes (CHP). In this study, an improved hydrologic-hydrodynamic model coupled with a glacier mass balance module was developed to enhance flood simulations in CA. The effects of the CHP on future flood inundation and the subsequent socioeconomic exposures were also investigated. We found that the simulations of daily streamflow and flood magnitudes improved significantly over the selected hydrological stations after considering the glacier mass balance. Our estimations indicated that the flood inundation and its dynamic evolution generally agreed with satellite observations. Moreover, CHP-induced (rainfall-induced) flood inundation plays a significant role in China’s Xinjiang and Tajikistan (other regions of CA). The CHP would amplify the effects of future flood on socioeconomics in CA, with population (Gross Domestic Productivity, GDP) exposure up to 2.25 million persons/year (150 billion $ PPP/year) for 2071 – 2100. These findings could provide scientific evidence to improve the understanding of CHP effects on future floods and the subsequent exposures, informing the prioritization and design of flood mitigation strategies in CA.
Three-dimensional deformation over Shuguang oilfield in Liaohe River Delta, China, from multi-track InSAR and its impacts on ﬂood inundation
Authors: Tang Wei
Published: March 2024

Land subsidence has a great impact on coastal plains near sea level, leading to permanent inundation. The Shuguang oilfield, located in Liaohe River Delta (LRD), northeastern China, is one of the most significant subsidence areas as a direct consequence of oil production. We studied the production-induced deformation in the LRD region by Sentinel-1 radar images. Images from two ascending and two descending tracks are processed by an Interferometric Synthetic Aperture Radar (InSAR) time series analysis over the 2017 to 2021 period, providing deformation rate maps and time series in the radar line-of-sight (LOS) direction.Previous researches carried out in this area assumed the oil production-induced deformation corresponds only to vertical deformation. Here, we proposed a method to retrieve the three-dimensional (3D) displacement field over the oilfield. We retrieved the vertical and east-west deformation components by combining the multiple InSAR geometries LOS observations and retrieved the north-south component based on the assumption of a physical relationship between the horizontal and vertical displacement.The derived 3D displacement fields over Shuguang oilfield exhibit a circular subsidence bowl with a maximum subsiding rate reaching 212 mm/year, accompanied by a centripetal pattern of horizontal displacements with maximum rates up to 50-60 mm/year moving towards the subsidence center. The retrieved-3D displacements are in good agreement with predictions from the geomechanical modeling by assuming a disk-shaped reservoir subject to a uniform reduction in pore fluid pressure. Finally, we show the importance of knowing both the vertical and horizontal displacement in characterizing the lateral boundary of the subsurface reservoir.The Liaohe River Delta region is often affected by heavy rainfall and storm surge in flood season, and flood disasters occur frequently in this low-lying coastal area. This deltaic region is vulnerable to floods not only from the extreme heavy rainfall, but also the land subsidence related to oil production. By spatial overlay analysis of the land subsidence distribution and the inundation extent of a flood event in August 2022, we reveal the impacts of land subsidence on flood inundation in this region. Our findings provide scientific support for oil production-related subsidence control and flood planning and designing in this deltaic region.
Recent changes in the morphodynamic of the Ebro river mouth (NW Mediterranean Sea)
Authors: Calvillo Melero Benjamí , Grifoll Colls Manel , Gracia García Vicente
Published: March 2024

The Ebro River Delta, as one of the largest river deltas in the NW Mediterranean region, is a lobate fluvial-wave dominated delta with a principal freshwater discharge channel (order of 102 m3/s of regular conditions). The lowest part of the delta and the river mouth has suffered natural-induced shifting configuration in the last century. Recent morphologic changes on the Ebro River mouth has lead to a formation of an island and tomobolo with a consequent deviation of the main channel of the freshwater discharge southwards. Field survey carried out of November 2023 has suggested a shifting of the preferential freshwater discharge from North mouth to an incipient North-East mouth. This investigation pursue to identify the main reason of this morphological changes and discern the eventual perpetuity of the new configuration. The analyses combine the use of satellite images to identify the shoreline modifications, jointly with “in situ” data of bathymetry, waves and currents. Likely the island formation and subsequent tombolo is due to the recent absence of NE storms combined with extremely low river discharge (including regulated floods) due to the drought conditions that is suffering the Ebro river basin during the last years.
Synergistic effect of land-atmosphere coupling and climate change on flash droughts
Authors: Yuan Xing
Published: March 2024

The land-atmosphere coupling is responsible for flash droughts as the reduced soil moisture increases sensible heat and consequently the lifting condensation level, which ultimately reduces convective precipitation. Meanwhile, the decrease in atmospheric humidity increases the evaporation demand, facilitates the drying of the land surface, and triggers flash droughts with rapid onset and devastating impact. However, whether the role of the land-atmosphere coupling is enhanced or weakened under climate change remains elusive, as previous studies are usually based on unconditional analysis without discriminating dry or wet extremes. Here, we start the investigation from a mega-flash drought occurred over the Yangtze River basin in southern China during the summer of 2022. Both the offline high-resolution land surface model simulations and the CMIP6 climate model data are used for the analysis. It is found that high temperature aggravates the 2022 flash drought onset speed and intensity, highlighting the importance of climate warming. Even under natural climate forcings, the land-atmosphere coupling increases the risks of flash drought intensity and onset speed. The synergy of coupling and anthropogenic climate change would further increase the risks. The synergistic effect on the long-term trends of flash droughts is also being explored, shedding light on the mechanism of flash droughts in a changing climate.
Development of a Distributed Physics-informed Deep Learning Hydrological Model for Data-scarce Regions
Authors: Zhong Liangjin , Lei Huimin , Yang JIngjing
Published: March 2024

Climate change has exacerbated water stress and water-related disasters, necessitating more precise runoff simulations. However, in the majority of global regions, a deficiency of runoff data constitutes a significant constraint on modeling endeavors. Traditional distributed hydrological models and regionalization approaches have shown suboptimal performance. While current data-driven models trained on large datasets excel in spatial extrapolation, the direct applicability of these models in certain regions with unique hydrological processes may be challenging due to the limited representativeness within the training dataset. Furthermore, transfer learning deep learning models pre-trained on large datasets still necessitate local data for retraining, thereby constraining their applicability. To address these challenges, we present a physics-informed deep learning model based on a distributed framework. It involves spatial discretization and the establishment of differentiable hydrological models for discrete sub-basins, coupled with a differentiable Muskingum method for channel routing. By introducing upstream-downstream relationships, model errors in sub-basins propagate through the river network to the watershed outlet, enabling the optimization using limited downstream runoff data, thereby achieving spatial simulation of ungauged internal sub-basins. The model, when trained solely on the downstream-most station, outperforms the distributed hydrological model in runoff simulation at both the training station and upstream stations, as well as evapotranspiration spatial patterns. Compared to transfer learning, our model requires less training data, yet achieves higher precision in simulating runoff on spatially hold-out stations and provides more accurate estimates of spatial evapotranspiration. Consequently, this model offers a novel approach to hydrological simulation in data-scarce regions with unique processes.
Paleomagnetic Dating Constraints on the Genesis of the Leqingla Pb-Zn Deposit, South Tibet, China
Authors: Xing Longyun , Cheng Xin , Wu Hanning
Published: March 2024

The Leqingla deposit serves as a representative skarn-type Pb-Zn deposit in the Gangdese polymetallic belt, South Tibet, China. Although numerous studies have been conducted on this deposit, there is no consensus about its specific genesis, particularly concerning the timing of mineralization. Recent studies indicate that paleomagnetic dating techniques, employed on newly formed magnetic carrier associated with mineralized fluids, permit precise determination of mineralization timing. Hence, a systematic paleomagnetic and petrologic investigation was conducted on the host rock of the Leqingla deposit, which is characterized by the middle Permian Luobadui Formation sandstone. The results reveal that the dominant magnetic carrier in the host rock is hydrothermal authigenic pyrrhotite. The stable characteristic remanent components display maximum clustering when flattened to -5.5% ± 13.5% after tilt corrected. The obtained paleomagnetic pole (Plat = 74.5°N, Plong = 222.5°E, at N = 8, A95 = 2.9°) is consistent with that of the Pana Formation volcanic rock in the same area. Further combined with the chronological and geological evidences, we refer that the hydrothermal authigenic pyrrhotite in the host rock may record chemical remagnetization information acquired between 54-47 Ma. The magmatic activity (54-47 Ma) induced by the India-Asia collision is closely related to remagnetization and the formation of the Leqingla deposit.
Are there any links between geomagnetic field variations and hydrological cycles in the South China Sea since the Late Pleistocene
Authors: Yang Xiaoqiang
Published: March 2024

A correlation between Earth’s magnetic field and climate change has been debated for over forty years, despite significant ~100- and ~41-kyr periods in both the stacked relative paleointensity and inclination records. In this paper, we construct a master relative intensity curve (SPIS-150) over the past ~150 kyr by stacking the data from one new core (PC27) with published intensity curves for the northern South China Sea. Additionally, we calculate the Dole effect from the sea surface temperature (SST) and d18O of planktonic foraminifera based on two cores, PC83 and PC27, and use it as a precipitation proxy. The results of this study show that geomagnetic field intensity lows are related to rich rainfall. During the ~23 kyr period, the relative intensity shows in-phase variations with simulating 0-30°N terrestrial precipitation, which shows that the superimposed effect of insolation and geomagnetic fields influences low-latitude precipitation. The strong summer monsoon predominated by insolation carries rich water vapor, which forms low cloud cover under one cloud-formation physical process where the geomagnetic field modulates galactic cosmic rays (GCRs) and leads to aerosol-related cloud condensation nuclei (CCN) formation. Deeper cloud cover produces strong rainfall in low-latitude regions.
Non-equilibrated ocean alkalinity enhancement influences nitrogen retention and export 
Authors: Suessle Philipp , Schulz Kai , Riebesell Ulf
Published: March 2024

Ocean alkalinity enhancement (OAE) has been proposed as a carbon dioxide removal technology (CDR) allowing for long-term storage of atmospheric carbon dioxide (CO2) in the ocean. By changing the carbonate speciation in seawater, OAE may alter plankton communities and the particle export they drive. Using mesocosms in the mesotrophic Raunefjord, Bergen (Norway), we employed five different alkalinity levels for each, a lime- and olivine-based OAE scenario. Total alkalinity (TA) was raised in increments of 150 µmol kg-1­ (ΔTAmax = 600 µmol kg-1) using NaOH solutions. Seawater pCO2 was left to equilibrate with the atmosphere, leading to strong (pHmax = 8.80) but transient changes in carbonate chemistry. In concert with TA, CaCl2 (lime-based) or MgCl2 (olivine-based) was added to simulate the respective cation increase during mineral application. Additionally, equal amounts of Na2SiO3 (75 µmol L-1)was added to all olivine-based mesocosms to simulate the release of silicate whilst separating it from TA effects. Here, we provide insights of the two different OAE approaches on the flux and attenuation of sinking particles. After 49 days of non-equilibrated OAE, the community-mediated cumulative export flux of major elements (POC, PON, POP, BSi) was higher in the olivine- compared to the lime-based application. Preferential remineralization of nitrogen over carbon within the export flux decreased with TA, suggesting a potential nitrogen loss to the surface ocean, potentially shortening productive bloom periods and thus decreasing export production of carbon. This potential negative feedback on atmospheric CO2 levels under OAE warrants further investigation, specifically with respect to its dependence on plankton community composition, heterotrophic nitrogen remineralization, and the chosen alkalinity enhancement approach.
D-Vine GAM Copula based Quantile Regression with Application to Ensemble Postprocessing
Authors: Jobst David , Möller Annette , Groß Jürgen
Published: March 2024

Temporal, spatial or spatio-temporal probabilistic models are frequently used for weather forecasting. The D-vine (drawable vine) copula based quantile regression (DVQR) is a powerful tool for this application field, as it incorporates important predictor variables from a large set by a data-driven sequential forward selection procedure and is able to model complex nonlinear relationships among them. However, the current DVQR does not always explicitly and economically allow to account for additional covariate effects, e.g.  temporal or spatio-temporal information. Consequently, we propose an extension of the current DVQR, where we parametrize the bivariate copulas in the D-vine copula through Kendall's Tau which can be linked to additional covariates. The parametrization of the correlation parameter allows generalized additive models (GAMs) and spline smoothing to detect potentially hidden covariate effects. The new method is called GAM-DVQR, and its performance is illustrated in a case study for the postprocessing of 2m surface temperature forecasts. We investigate a constant as well as a time-dependent Kendall's Tau. The GAM-DVQR models are compared to the benchmark method gradient-boosted Ensemble Model Output Statistics (EMOS-GB). The results indicate that the GAM-DVQR models are able to identify time-dependent correlations as well as relevant predictor variables and significantly outperform the state-of-the-art method EMOS-GB. Furthermore, the introduced parameterization allows using a static training period for GAM-DVQR, yielding a more sustainable model estimation in comparison to DVQR using a sliding training window. 
Robust Relationship between Mean State Moisture and Interannual MJO Activity in Observations and CMIP6 Models
Authors: Kang Daehyun , Kim Daehyun , Kang Seon-Yu
Published: March 2024

The Madden-Julian Oscillation (MJO) is the dominant intraseasonal variability of eastward propagating atmospheric disturbances in the tropics. From its vast impacts on the sub-seasonal extreme events and predictability, the mean states controlling the MJO activity have been investigated. For example, the robust relationship between the Quasi-Biennial Oscillation (QBO) and the MJO has been suggested in the past several years. In the easterly QBO winters, the MJO exhibits stronger activity than the westerly QBO winters. Our study suggests another crucial factor that affects the MJO: a meridional humidity gradient of the atmospheric column in the vicinity of the Maritime Continent. With the change in the shape of the column humidity distribution, MJO variance shows a robust interannual modulation regardless of the QBO. The northward (southward) extension of the moisture increases (decreases) the mean state meridional humidity gradient, which leads to MJO development (decay) over the MC with increasing (decreasing) horizontal moisture advection. This robust relationship between mean state humidity and MJO activity is investigated in the CMIP6 models as two aspects: i) interannual variation of MJO and ii) future change in MJO. Both simulated MJO activities are largely affected by the mean state MHG, supporting the robust role of mean state moisture on the MJO shown in the observations. The results of this study provide a further understanding of seasonal MJO activity and sub-seasonal predictability.MJO activity and sub-seasonal predictability.
The impacts of Soil Properties on the water and energy cycles modeling of Noah-mp in China
Authors: qian rui
Published: March 2024

Land surface models are useful tools in investigating water and energy cycle. Soil hydraulic properties (SHP) play a major role in the hydrological and ecological processes crossing scales. However, many land models determine SHP only based on land use and soil types, neglecting the heterogeneity of SHP. We hypnotize that using distributed SHP, both horizontally and vertically, could further improve the physics and performance of land surface models.This study evaluates the performance of Noah-MP land model using distributed SHP. We first perform variance-based Sobol sensitivity analysis to detect the global sensitivity of nine of the Noah-MP parameters to output water and energy variables. Based on the sensitivity analysis, we carry out regional simulation to evaluate the effects of spatial SHP on Noah-MP simulated water and energy cycle, we mainly focus on pore size distribution index, saturated water content, saturate hydraulic conductivity, which can be obtained from various soil datasets. The simulation is configured for the mainland of China and run at 3-hourly 0.1°×0.1°resolution between 1981 and 2018. Results show that, when compared to the lookup table soil parameterization schemes, using distributed SHP not only improves the accuracy of simulated runoff and evapotranspiration, but also enhances Noah-MP in characterizing the reliability of soil moisture spatial pattern in six major river basins of China. In addition, the vertical heterogeneity to the SHP further increases NSE of runoff and lowers RMSE of soil moisture.This study suggests that Noah-MP performance can be improved by using value of distributed and vertical heterogeneity of soil properties as input of soil hydraulic parameters.
Soil warming influences organic carbon composition at the microscale in Blodgett Forest
Authors: Rowley Mike , Pena Jasquelin , Marcus Matthew , Porras Rachel , Pegoraro Elaine , Torn Margaret , Nico Peter
Published: March 2024

The impact of warming on the soil organic carbon (SOC) cycle and its potential positive feedback with increasing atmospheric CO2 concentrations is of global concern. Earth System Models currently predict that warming will increase soil CO2 efflux faster than net primary productivity (Crowther et al., 2016); yet there are still large uncertainties associated with these modelled estimates, which can be reduced by process-based observations from whole-soil warming experiments. To identify the influence of 7.5 years of +4°C whole-soil warming on SOC and its elemental associations at the microscale, we used scanning transmission X-ray spectromicroscopy at the carbon K-edge (STXM C NEXAFS). We focused our analyses on soils collected from three depth intervals (10-20, 40-50, 60-70 cm) at the control and warmed plots from the whole-soil warming project at Blodgett Experimental Forest (granitic Alfisols). Relative to control plots, samples from the warmed plots had elevated aromatic and phenolic C content, and this observation was most pronounced in the 40-50 cm depth samples. This result differed from previous observations at the bulk-soil level (Ofiti et al., 2021), which demonstrated a decrease in the relative abundance of these compound classes with warming, particularly at depth. These contrasting results may be explained by a difference in SOC dynamics at the bulk scale relative to the microscale, with STXM investigating SOC bound in organo-mineral assemblages at the microscale, while bulk soil measurements include larger partulate organic matter. It could also be indicative of the changes in root dynamics with warming that were also recorded in Ofiti et al. (2021). The STXM data also showed that organic carbon was strongly associated with calcium in these acidic soils, which had a more plant-like nature than C associated with iron. This supports similar observations, which were recently made in soils from an acidic grassland soil series at Point Reyes, California that had developed in a different parent material (sandstone; Rowley et al., 2023). This study highlights the importance of investigating how organo-mineral or -metal associations will respond to changing environmental conditions at various analytical scales. ReferencesCrowther et al., 2016. Quantifying global soil carbon losses in response to warming. Nature 540(7631), 104-108.Ofiti, et al., 2021. Warming promotes loss of subsoil carbon through accelerated degradation of plant-derived organic matter. Soil Biology and Biochemistry 156, 108185.Rowley et al., 2023. Association between soil organic carbon and calcium in acidic grassland soils from Point Reyes National Seashore, CA. Biogeochemistry 165, 91-111.