bluuebunny/crossref_metadata_2025 huggingface dataset:
Responses of Phytoplankton Communities to Internal Waves inOligotrophic Oceans
Authors: xiao wupeng , ma lingqi , bai xiaolin , Laws Edward , guo cui , liu xin , Chiang Kuo-Ping , gao kunshan , huang bangqin
Published: March 2024

Understanding the potential impacts of internal waves on phytoplankton communities in oligotrophic oceans remains an important research challenge. In this study, we elucidated the impact of internal waves on phytoplankton communities through a comprehensive 154-hr time-series of observations in the South China Sea (SCS). We identified distinctive variations in phytoplankton pigment biomass and composition across the upper, middle, and lower layers of the euphotic zone, which we attributed to the perturbations triggered by internal waves. Phytoplankton other than Prochlorococcus in the lower, nutrient-replete layer likely benefitted from allochthonous nutrients introduced by internal waves, but their growth rates were constrained by light limitation, and their pigment biomass was held in check by microzooplankton grazing. In contrast, in the upper, nutrient-depleted layer, the relative abundance of Prochlorococcus increased, likely because of the ammonium regenerated by zooplankton. The middle layer, characterized as the deep chlorophyll maximum layer, exhibited a dynamic equilibrium characterized by nutrient and light co-limitation. This equilibrium resulted in high nitrate assimilation and growth by phytoplankton. The balancing of those rates by significant grazing losses maintained total chlorophyll a concentrations at a high level. Based on these findings, we proposed a three-layer euphotic zone structure characterized by distinct physiological conditions, nutrient-light dynamics, grazing pressure, and phytoplankton responses to internal waves. This three-layer paradigm elucidated the intricate interplay between internal waves and phytoplankton communities and provided insights into the mechanisms that govern primary production and carbon cycling in oligotrophic oceanic ecosystems.
Optimization of geothermal energy production from fracture-controlled reservoirs via 3D numerical modeling and simulation
Authors: Partl Ondrej , Rioseco Ernesto Meneses
Published: March 2024

We develop a computation framework from scratch that allows us to conduct 3D numerical simulations of groundwater flow and heat transport in hot fractured reservoirs to find optimal placements of injection and production wells that sustainably optimize geothermal energy production.We model the reservoirs as geologically consistent randomly generated discrete fracture networks (DFN) in which the fractures are 2D manifolds with polygonal boundary embedded in a 3D porous medium. The wells are modeled as line sources and sinks.The flow and heat transport in the DFN-matrix system are modeled by solving the balance equations for mass, momentum, and energy.The fully developed computational framework combines the finite element method with semi-implicit time-stepping and algebraic flux correction.To perform the optimization, we use various gradient-free algorithms.We present our latest results for several geologically and physically realistic scenarios.
Emplacement and erosion of valley-filling basalt lavas in shifting Quaternary environments of the Garibaldi Volcanic Belt, British Columbia, Canada
Authors: Borch Annie , Russell James Kelly , Barendregt Rene , Friele Pierre
Published: March 2024

The Cheakamus basalts are a set of ~31 km long, 1.65 km3 valley-filling olivine basalts which erupted into the glaciated Callaghan-Cheakamus Valley system of the Garibaldi Volcanic Belt (GVB), British Columbia. Combined paleomagnetic and radiometric (40Ar/39Ar) analysis dates the lavas as a short-lived (< 2 ka duration) eruption at 15.95 ± 7.9 ka (2σ); additional field evidence, including well-glaciated lava flow surfaces overlain by till, indicate the eruption coincided with the early stages of the Fraser Glaciation (LGM) at ~20-18 ka. The lavas preserve features indicative of a landscape hosting diverse and dynamic paleoenvironments. Subaerial eruption of basalt lava filled an ice-free Callaghan Creek drainage system before inundating and damming of the paleo-Cheakamus River, creating an upstream rising body of water. Periodic overtopping of the lava dam resulted in syn-eruptive intermittent flooding and overtopping of lavas expressed by discontinuous lenses of interflow sediment and well-developed entablatures in the upper portions of lava flows. Rare instances of enigmatic cooling columns indicate localized ice contact with glaciers that partially filled the Cheakamus Valley. Emplacement features and morphologies in the Cheakamus Valley have been heavily altered by the erosional overprinting of a glacial lake outburst flood (GLOF) that preliminary 10Be analysis dates at the close of the LGM (11-10 ka). Lavas in the Callaghan valley remain untouched by the GLOF. Their aerial extent and distribution, especially at high elevations in tributary valley mouths suggest bottlenecking and backing-up of lavas due to narrowing in valley topography. Current work combines field mapping and analogue modelling and aims to provide insight into the emplacement dynamics of effusive lavas in the steep, confined terrain of the BC Coast Mountains. Despite, and in part because of, their heavily modified morphology, the Cheakamus basalts act as an excellent recorder of both effusive volcanic processes and the paleoenvironments into which they erupted. Their thorough and accurate analysis is especially pertinent temporally, as they erupted during a time of glacial flux and can provide additional evidence for the timing and location of the advancing Cordilleran ice sheet. Spatially, the Cheakamus basalts are proximal to population centers and transport infrastructure and thus have implications for potential volcanic hazards and attendant risks, as any future effusive, valley-filling basaltic eruption from the GVB will likely share similar emplacement characteristics and processes.
Exploring the landscape heterogeneity and the hydrological diversity in three contrasted observatories of the French critical zone research infrastructure OZCAR
Authors: Ackerer Julien , Kuppel Sylvain , Braud Isabelle , Pasquet Sylvain , Fovet Ophélie , Probst Anne , Pierret Marie Claire , Ruiz Laurent , Tallec Tiphaine , Lesparre Nolwen , Weill Sylvain , Flechard Christophe , Probst Jean Luc , Marçais Jean , Riviere Agnes , Habets Florence , Anquetin Sandrine , Gaillardet Jerome
Published: March 2024

The French OZCAR critical zone network offers the opportunity to conduct multi-site studies and to explore the critical zone functioning under contrasted climate, geology, vegetation and land use. In this study, an integrated modeling of the water cycle is performed with the ecohydrological model EcH2O-iso in three long-term observatories: (1) the Naizin watershed characterized by an oceanic climate, a metamorphic bedrock and an intensive agriculture (north-west of France, AgrHyS observatory); (2) the Aurade watershed, a watershed with a warmer semi-continental oceanic climate, a sedimentary geological substratum and a crop cover with a wheat-sunflower rotation (south-west of France, Aurade observatory) and; (3) the Strengbach watershed characterized by a mountain climate, a granitic bedrock, and a beech-spruce forest cover (north-east of France, OHGE observatory).Modeling robustness is evaluated by taking advantage of the large database for critical zone sciences including stream flow, water level in piezometers, and evapotranspiration fluxes measured from climatological stations and flux-towers located in the watersheds. Our comparative study brings these general outcomes: (1) the long term CZ evolution controlling the regolith thickness strongly impacts the total water storage in watersheds; (2) the Quaternary geomorphological evolution influences the current hydrological partitioning and the separation of hydrologically active and inactive water storage; (3) Both internal watershed characteristics and external forcings, such as current atmospheric forcing and recent land use need to be considered to infer stream persistence and to understand hydrological diversity; and (4) the observed hydrological diversity cannot be fully understood without considering a continuum of time scales in CZ evolution. Overall, this work illustrates the strength of critical zone networks, allowing a new level of multi-site and comparative studies that are crossing several observatories and encompassing a wide diversity of geology and climate. 
A Two-dimensional Model for the Gas Transport in the Unsaturated Zone with the Soil Aeration
Authors: Lo Jui-Hsiang , Smits Kathleen , Zimmerle Daniel
Published: March 2024

To develop methods based on integrating the two-phase (liquid and gas) flow and free flow in the porous media to optimize the operation of subsurface gas venting, we developed a two-dimension soil aeration model based on the coupling of two-phase flow (liquid and gas) in the porous media with the single-phase flow (methane, CH4) in the free-flow domain under homogeneous, isotropic, and isothermal conditions. The dissolution, bioreaction, and thermal diffusion of CH4 are not included in the model. Numerical experiments were conducted with diverse near-surface meteorological conditions, soil properties (e.g., porosity, soil layering, air permeability, and soil moisture), and the deployment of venting bar holes to study the effects of environmental conditions and venting system designs on the gas flow in the subsurface. Simulation results not only demonstrated the capability of the soil aeration model on the prediction of the migration of the residual CH4 concentration in the subsurface due to the venting but also highlighted the influence of soil permeability, deployment of venting bar holes, and the venting pressure on the change in residual gas concentration in the unsaturated zone. During the soil aeration, the low soil permeability impacted the migration of advective air flow by venting in the soil and prolonged the operation time of the soil aeration. Furthermore, the Peclet number of the gas migration significantly decreased from the center of the venting bar hole with the decrease in soil permeability and venting pressure. The variation of venting pressure is more sensitive to the development of venting flow rates than that of the number of venting bar holes. The proposed 2D soil aeration model and approaches of evaluation of soil aeration in this study provide insights to investigate the multiphase flow in the subsurface due to soil aeration operation under various environmental conditions and venting strategies.
Full Moon Phase: Lunar Surface Charging in Plasma Sheet - PIC Simulation
Authors: Baraka Suleiman , Hosseini Sona , Gronoff Guillaume , Rankin Robert
Published: March 2024

Understanding lunar surface charging mechanisms is pivotal for unravelling the complexities of the lunar environment. This research utilizes particle-in-cell (PIC) code simulations to investigate the breakdown of plasma sheet quasi-neutrality upon encountering the lunar surface. Our simulation demonstrates that this disruption in the correlation between ion and electron densities instigates significant charging phenomena on the lunar surface. These simulations provide a detailed perspective on the intricate relationship between the plasma sheet and lunar surface charging dynamics, offering crucial insights into lunar environmental dynamics. Additionally, this study explores ion and electron dynamics in the lunar wake, extending up to several lunar radii. The findings contribute valuable knowledge to space weather studies and facilitate a better understanding of lunar surface interactions crucial for space exploration endeavours.
 

This illustration depicts the breakdown of plasma quasi-neutrality at the lunar surface, resulting in a positively charged lit side and a negatively charged dark side. It's important to note that despite the dominance of positive and negative charges, the total number densities remain equivalent on both lunar surfaces.
Human influences on spatially compounding flooding and heatwave events in China and future increasing risks
Authors: Qian Cheng , Ye Yangbo , Bevacqua Emanuele , Zscheischler Jakob
Published: March 2024

Attribution of high-impact weather events to anthropogenic climate change is important for disentangling long-term trends from natural variability and estimating potential future impacts. Up to this point, most attribution studies have focused on univariate drivers, despite the fact that many impacts are related to multiple compounding weather and climate drivers. For instance, co-occurring climate extremes in neighbouring regions can lead to very large combined impacts. Yet, attribution of spatially compounding events with different hazards poses a great challenge. Here, we present a comprehensive framework for compound event attribution to disentangle the effects of natural variability and anthropogenic climate change on the event. Taking the 2020 spatially compounding heavy precipitation and heatwave event in China as a showcase, we find that the respective dynamic and thermodynamic contributions to the intensity of this event are 51% (35–67%) and 39% (18–59%), and anthropogenic climate change has increased the occurrence probability of similar events at least 10-fold. We estimate that compared to the current climate, such events will become 10 times and 14 times more likely until the middle and end of the 21st century, respectively, under a high-emissions scenario. This increase in likelihood can be substantially reduced (to seven times more likely) under a low-emissions scenario. Our study demonstrates the effect of anthropogenic climate change on high-impact compound extreme events and highlights the urgent need to reduce greenhouse gas emissions.
Occurrence and Distribution of Per- and Polyfluoroalkyl Substances (PFAS) in the Coastal Groundwater of Eastern Saudi Arabia
Authors: Benaafi Mohammed , Tawabini Bassam , M. Al-Areeq Ahmed , Aljundi Isam
Published: March 2024

PFAS (per- and polyfluoroalkyl compounds) have emerged as prevalent pollutants in groundwater due to their vast past utilization in consumer products and industrial applications, coupled with their remarkable persistence. The current research investigated 17 PFAS chemicals in 10 groundwater samples from coastal multi-layered aquifer systems in Eastern Saudi Arabia, with seven samples from shallow aquifers (2-30 m) and three samples from deep aquifers (>70 m). The analysis utilized solid phase extraction and liquid chromatography-tandem mass spectrometry (LC-MS/MS) in accordance with EPA Method 537 and ISO 25101, with a detection limit of 10 ng/L. The results show that four PFAS substances were detected with values above the detection limits in shallow groundwater samples: perfluorobutane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorooctanoic acid (PFBA), and perfluorobutane sulfonic acid (PFBS). In contrast, no PFAS compound was found in the deep wells. PFOS was found in 29% of the samples (2 out of 7) with a maximum value of 23.6 ng/L. PFBA and PFBS were found in 14% of samples at 11 and 53 ng/L, respectively. PFOA was found to have a concentration of 10.9 ng/L and a detection frequency of 14%. The occurrence of PFAS, although currently at minimal levels, suggests potential pollution of the coastal aquifer that requires continuous monitoring and assessment to determine the source, the extent of the contamination, and its potential impact on human health and the environment. Additionally, while the highest PFOS concentration remained below the EPA's lifetime health advisory of 70 ng/L, it exceeded Vermont's PFOS drinking water standard of 20 ng/L. Recent research has linked PFOS exposure through drinking water to immune effects in infants at levels as low as ten ng/L. Further research is needed to investigate the potential spreading of PFAS plumes, identify potential sources of contamination, assess the extent of environmental and human health impacts, and develop effective remediation strategies. The findings add to the global contribution of PFAS contamination, underscoring the importance of having a proactive approach to monitoring and managing these persistent environmental pollutants.
Dynamic Slip Rupture at a Layer-Half-space Interface: A Hybrid Finite Difference and Spectral Boundary Integral Equation Method for Numerical Simulation
Authors: Painuly Abhishek , Kunnath Ranjith
Published: March 2024

The propagation of rupture at the interface between a layer and a half-space, arising from their relative slipping, is commonly observed in geophysics and in technological materials. Fault ruptures develop as a consequence of ongoing aseismic interfacial movement caused by geological forces; and accumulation of stress over time ultimately leads to a sudden stress release resulting in seismic phenomena. In mathematical terms, it is a highly nonlinear and multiscale phenomenon that necessitates the accurate solution of elastodynamic equations and interfacial fault friction across an extensive domain over an extended time period. The most numerically efficient algorithm for simulating this process is the Boundary Integral Equation Method (BIEM). It computes field quantities at the fracture plane and reduces domain dimensionality of the problem by one, but its current applicability is mostly limited to planar interfaces and to unbounded geometries. BIEM computes elastodynamic fields at the fracture plane from a space-time traction history by utilizing suitable convolution kernels (dependent on the geometry and the material/bi-material characteristics across the interface). Applying BIEM to a geometry involving a layer over a half space presents significant challenges, particularly due to the difficulty in analytically deriving convolution kernels for finite geometry and in-plane deformations. Here, we develop an integrated approach, combining the traction formulation of BIEM (Ranjith, 2015) with the Finite Difference Method (FDM), to overcome these challenges. A hybrid FDM-BIEM has previously been used by Hajarolasvadi and Elbanna (2017) using the velocity formulation of BIEM (Geubelle and Rice, 1995) for unbounded geometries. In the present work, a fourth-order staggered-grid FDM is employed to model dynamic rupturing in a layer. The layer is adjoined by an elastic half-space. The elastodynamic equations in the half-space are handled using a BIEM. The FDM region incorporates a slip-weakening friction law at the fault interface using a thick fault zone model consisting of two grid rows (Madariaga, Olsen and Archuleta, 1998). By applying traction boundary conditions, it computes updated velocities in the domain, and passes them to BIEM. BIEM, in turn, responds with updated tractions at the boundary, utilizing convolution kernels derived by Ranjith (2015). We utilized the hybrid FDM-BIEM numerical algorithm to study the effect of finite layer thickness on rupture propagation, considering both homogeneous and bi-material fault interfaces. The results suggest that the present method has the capacity to effectively deal with a wide array of problems in finite domains often countered in both geophysics and technological domains.
Verifications of Week-1 to Week-4 Tropical Cyclone Forecasts in the Western North Pacific from the ECMWF 46-Day Ensemble
Authors: Tsai Hsiao-Chung , Hsu Han-Yu , Lo Tzu-Ting , Chen Meng-Shih
Published: March 2024

This study uses the ECMWF 46-day ensemble to evaluate the subseasonal forecasts of tropical cyclones (TCs) in the western North Pacific, including TC formations, tracks, intensity, and precipitation forecasts. TC formations and the subsequent tracks are objectively detected in both real-time forecasts and also the 20-year ECMWF reforecasts. Additionally, a spatial-temporal track clustering technique is utilized to group similar vortex tracks in the 101-member real-time forecasts for operational application. The forecast verification focuses on evaluating the influence of large-scale environmental factors on TC forecast skills during weeks 1-4, such as the Western North Pacific Summer Monsoon (WNPSM), Madden Julian Oscillation (MJO), and Boreal Summer Intraseasonal Oscillation (BSISO). The Precision-Recall (PR) curve is used to represent the imbalanced TC data instead of the Receiver Operating Characteristic (ROC) curve. Better TC forecast skills are observed if model initialized on MJO Phases 6 and 7 for the week-1 forecasts, and on MJO Phases 4 and 5 for the weeks 2 and 3 forecasts. Also, TC forecast skills are better if the cumulative percentage of the WNPSM index (Wang et al. 2001) is larger than 60%. This study also investigats the TC precipitation forecast skill around Taiwan area.The evaluation results obtained from this study has been integrated into the TC Tracker 2.0 system developed by Central Weather Administration (CWA). The system can generate a "Subseasonal TC Threat Potential Forecast" product to assist in disaster mitigation and water resources management for the Water Resources Agency. More details about the subseasonal TC forecast verifications and applications will be presented in the meeting
AFTERSLIP of 6 FEBRUARY 2023 KAHRAMANMARAS EARTHQUAKE SEQUENCE : PRELIMINARY RESULTS
Authors: Ayruk Efe T. , Turğut Muhammed , Farımaz İlay , Köküm Mehmet , Bilham Roger , Doğan Uğur
Published: March 2024

The Mw 7.8 earthquake of 2023 ruptured the southern (main) branch of the East Anatolian Fault (EAF), followed by the Mw 7.6 earthquake on the northern (Çardak Fault) branch of the EAF nine hours later. In March, we installed ten carbon-rod extensometers across segments of the main and northern branches of the ruptured faults, where potential slip deficits were considered possible, to investigate if afterslip continues. It is important to measure afterslip to understand the behaviour of a fault, if any, resulting from stresses associated with local coseismic slip deficits.  Seven of these extensometers recorded less than a few millimetres of slip since March. In Göksun near the western end of the Çardak fault, we recorded more than a 25 mm of accelerating afterslip preceding local aftershocks of magnitude ≤Mw5.1.The Mw 6.8 Elazığ-Sivrice earthquake of January 24, 2020, and the Mw 7.8 Kahramanmaraş earthquake of February 6, 2023, stopped in the Pütürge region, where it is named as Pütürge Gap. To understand why these two earthquakes terminated there, an array of five extensometers were ultimately deployed. One of the extensometers, which is 52 m long, shows that slip > 3.8 mm/yr continues at depth. Extensometers spaced 45 km apart recorded an eastward propagating subsurface creep event in September 2023. Four cGPS stations recording at 5 Hz were installed in an array to better investigate the subsurface evolution of aseismic slip on the Pütürge Fault in the village of Taşmış.
Investigating the effects of initial concentration and population distribution on the transport of aggregating nanoparticles in porous media
Authors: Katzourakis Vasileios , Chrysikopoulos Constantinos
Published: March 2024

         In order to investigate the migration of nanoparticles in porous media, the model developed by Katzourakis and Chrysikopoulos (2021) is applied  to simulate the transport of aggregating nanoparticles under various initial conditions. In the aforementioned model, nanoparticles may collide with each other and form larger particle structures with different mobility and reactivity characteristics. Individual particles as well as aggregates can be found suspended in aqueous phase or attached, reversibly and/or irreversibly, on the solid matrix. The aggregation process modelled after the Smoluchowski population balanced equation (PBE), is coupled with the conventional advection-dispersion-attachment (ADA) equation to form a system of coupled equations that govern the transport of aggregating nanoparticles. Particle collisions are expected to increase exponentially with increasing initial number of injected particles (N0). Therefore, substantially pronounced aggregation is expected when N0 is increased. Similarly, the initial particle diameter distribution of the injected particles is expected to affect the average size of aggregates and in turn influence their mobility in a porous medium. Several model simulations were performed with different N0 and particle diameter distributions. The results indicated the strong importance of taking into account the initial particle concentration and realistic particle diameter population distribution into consideration.
Intermittent Generation of Nonlinear Internal Waves on Continental Shelf
Authors: Bai Xiaolin
Published: March 2024

Internal waves have a wide range of scales but are typically unresolved in climate or global models. With an unprecedented capability of observing and simulating these processes, they are becoming increasingly important to quantify the upscale effect of these processes. As the largest marginal sea in the western Pacific, the South China Sea has the most energetic and frequent internal waves around the world. These waves are also affected by multiscale processes, climate changes, and anthropogenic impacts. There have been considerable advances in exploring the generation and propagation of internal waves in recent years. However, the understanding of the formation and fate of internal solitary-like waves on the continental shelf is still very limited. It is widely accepted that these internal waves generally originate from the Luzon Strait. They usually have regular occurrence and are phase-locked to tidal forcing in the Luzon Strait. However, we present field measurements showing an irregular occurrence of nonlinear internal waves on the northern shelf of the South China Sea. This irregular occurrence is in striking contrast to the prominent predictability of internal waves originating from the Luzon Strait. We reveal that the intermittent nature of the occurrence is due to the local generation of nonlinear internal waves on the continental shelf, in addition to the fission of shoaling internal waves. The results reported here are expected to apply to other shelf regions of the world's oceans.
Low-frequency variability of upper-ocean temperature in the Central Pacific Subantarctic Mode Water formation region since the 1980s
Authors: Jing Wandi , Luo Yiyong , Zhang Ronghua
Published: March 2024

Subantarctic Mode Water is a water mass with nearly vertically homogeneous physical properties in the Southern Ocean, which exhibits variability at various time scales. This study investigates the low-frequency variability of upper-ocean temperature in the Central Pacific Subantarctic Mode Water (CPSAMW) formation region since the 1980s using an eddy-resolving ocean model and two observation-based products. It is found that the CPSAMW core layer temperature has significant low-frequency variability, with an unusually cold period around 2000 and warm periods around 2005 and 2015, respectively. This low-frequency variability is closely related to the change in local mixed layer temperature, which in turn is mainly attributed to the change in surface latent heat flux resulting from the change in wind speed. Further analysis indicates that the low-frequency variability of wind speed in the CPSAMW formation region is dominated mainly by the Interdecadal Pacific Oscillation (IPO) and to a lesser extent by the Southern Annular Mode (SAM). This study reveals the relationship in the low-frequency variability of CPSAMW temperature with the IPO and SAM, and provides insight into the remote influence of Pacific decadal variability on SAMW variability.
Spatial scales of kinetic energy and its transfer across large-meso scales in the Arctic Ocean
Authors: Liu Caili , Wang Qiang , Danilov Sergey , Koldunov Nikolay , Mueller Vasco , Li Xinyue , Sidorenko Dmitry , Zhang Shaoqing
Published: March 2024

Despite the importance of the Arctic Ocean for the large-scale circulation and climate, there is still a knowledge gap in our understanding of the spatial characteristics of the Arctic Ocean circulation, especially for the mesoscale. This research diagoses the kinetic energy (KE) and its transfer features of a rich-eddy Arctic Ocean from eddy-resolved sea-ice model FESOM (Finite-Element/volumE Sea ice-Ocean Model)  at about 1km in horizontal resolution, revealing the KE spectra at spatial scales and the seasonality. There are two peaks in the kinetic energy spectral density, one at the gyre scale of the Arctic boundary currents (centered at 1700-2000km), and the other associated with the mesoscale (centered at 60km), both of which exhibit a power-law scaling typical for large circulation and ocean eddies, respectively. Energy transfer diagnosis shows that there is inverse-cascade KE pathway at a hundred of kilometers to several killometers, of which the KE transfer value from larger scales to smaller scales is negative. The seasonality of the eddy KE spectrum and energy transfer in upper ocean is found to be highly consistent to sea ice loss trend, while eddy KE in deep ocean shows not significant seasonal variations. 
Extreme precipitation detection ability of four high-resolution precipitation products dataset in Nepal
Authors: Subba Sunil , Ma Yaoming , Ma Weiqiang , Han Cunbo
Published: March 2024

Due to Nepal's propensity for extreme precipitation (EP), it is essential to thoroughly research and comprehend the pattern that these occurrences have followed in previous years. However, precise precipitation information for EP research from densely-gauged networks is still difficult to obtain in mountainous countries like Nepal. This will consequently impede the dissemination of knowledge pertaining to the variability of extreme precipitation events in Nepal. The lacking factors in the current research trend could be attributed to the following points: (1) Very few to none studies that utilized the recently released high-resolution precipitation products in Nepal to identify their EP detection ability, (2) Most of the studies focused on the characterization of EP events in Nepal rather than its spatial and temporal variability. In order to address these issues, four high-resolution precipitation product datasets (PPDs) were evaluated for their extreme precipitation detection ability across Nepal from 1985 to 2020, namely, ERA5 Land reanalysis data, satellite-based precipitation data (PERSIANN_CCS_CDR), and merged datasets (CHIRPS_V2.0 and TPHiPr). The Mann-Kendall test trend, Sen's slope estimator, and various statistical and categorical indices were used to assess how well these PPDs performed. TPHiPr merged dataset represented monthly precipitation estimates better than other PPDs. In addition to having the highest CSI and the highest ACC, TPHiPr also has a high POD and a low FAR. As a result, it can be said that TPHiPr is the best PPD for determining whether there is 0.1 mm of precipitation per day across Nepal or not. Since it had fewer representational errors for the majority of the EP indices, TPHiPr was also rated as the best in terms of their temporal representation. TPHiPr dataset and the observed dataset showed stronger correlations for some EP indices, including frequency EP indices (R10mm, R20mm, and R25mm) and intensity EP indices (RX1 day, RX5 day, PRCPTOT, and R99p). Hence, it performed better than other PPDs in accurately capturing the spatial distribution of EP occurrences in Nepal for the period of 1985 to 2020 based on the aforementioned facts. This dataset can be used to improve existing knowledge in Nepalese hydrometeorology and climate research.
Ice-nucleating particles in springtime cold-air outbreaks associated with Arctic haze
Authors: Raif Erin , Barr Sarah , Tarn Mark , McQuaid James , Daily Martin , Abel Steven , Barrett Paul , Bower Keith , Field Paul , Carslaw Kenneth , Murray Benjamin
Published: March 2024

Concentrations of ice-nucleating particles (INPs) were measured in springtime cold-air outbreaks over the Norwegian and Barents Seas using filter samples taken on board the FAAM BAe-146 aircraft. These measurements of INP concentrations were comparable to the highest INP concentrations previously observed in the Arctic and were similar to typical terrestrial midlatitude INP concentrations. This is important because shallow cloud systems such as those in mid- to high-latitude cold-air outbreaks are highly sensitive to INPs and are a highly uncertain contributor to cloud feedbacks. To investigate the types of aerosol responsible for this high INP concentration, we used aerosol-size data from underwing optical probes to derive an active site density of the INP samples. By comparing to laboratory derived active site densities of different aerosol types, this suggested that sea spray was unlikely to be a dominant INP type and that there were likely to be strong biological and dust components to the INP population. Scanning electron microscopy with energy-dispersive spectroscopy used on selected filters revealed that sub-micron particles were dominantly sulphates and carbonaceous, while super-micron particles were dominantly mineral dust.Samples taken above the cloud decks had greater active site densities than those below, and back-trajectory analysis and meteorological conditions suggested a lack of obvious local INP sources. We hypothesise that the high INP concentration is most likely to be associated with aged aerosol that has accumulated over the Arctic (Arctic Haze).  These high INP concentrations imply that these clouds may have a more negative cloud-phase feedback than their Southern Ocean equivalents.
Geological Records of Past Cyclones Preserved in the Beach Ridge Systems on the East Coast of India
Authors: Kumar Rahul , Switzer Adam , Nugraha Abang , Singh Raj , Banerjee Santanu , Rath Sunita , Horton Benjamin , Prizomwala Siddharth , Bristow Charles
Published: March 2024

The Bay of Bengal is a well-known hotspot for cyclone formation. Multiple recent cyclones, such as the Odisha Super Cyclone in 1999 and Cyclone Fani in 2019, along with a series of historical cyclones, have severely impacted the east coast of India, particularly the coastal regions of Odisha and West Bengal States. However, the existing cyclone record from the area is insufficient for multi-decadal recurrence analysis, rarely extending beyond last few decades. Hence, understanding and integrating historical, prehistorical, and geological cyclone records from the area can provide information on the social, economic, and environmental impacts of cyclones. This information will aid in planning response strategies and implementing policies to mitigate cyclone effects. This study investigates the geological record of cyclones buried in the prograded beach systems near Konark in Odisha over the past few hundred years. Shore-normal ground penetrating radar (GPR) reflection profiles were collected using the 250 and 500 MHz antennas of the pulseEKKO PRO GPR system. Sediment cores and excavated faces were analysed along the same GPR lines, and optically stimulated luminescence ages provide a chronological framework over the last 300 years. Processed GPR profiles exhibit a number of high-angle erosional surfaces. These surfaces were likely caused by erosion during severe cyclones in the region, spanning at least the last three centuries. Eight such erosional surfaces were identified from the GPR profile near Konark. Trench and core data from the swales also highlight several distinctive layers rich in heavy minerals, possibly the result of repetitive cyclones in the area. One prominent sand layer gives an interim age of 150 years, likely linked to a late 19th century washover event. The data presented in this study indicate that geological records can be used to build a long-term cyclone record for the area. Given the increasing population density in the region, a comprehensive cyclone record can provide valuable insights into the changes in frequency and intensity over the long term, which can be used to inform decision-making processes for coastal management and development.
Tracing the origin of parental fluids and paleo-temperature distribution in fault zones: case studies from the Carboneras Fault (Spain) and Lemnos Island (Greece)
Authors: Moretto Vincenzo , Del Sole Leonardo , Curzi Manuel , Dallai Luigi , Vignaroli Gianluca , Viola Giulio , Balsamo Fabrizio , Berio Luigi Riccardo , Grathoff Georg , Warr Lurence Noel , Aldega Luca
Published: March 2024

Multiple episodes of brittle deformation tend to increase the structural complexity of fault zones. This commonly results in the development of juxtaposed and non-coeval distinct Brittle Structural Facies (BSF) formed at different times, depths, and temperature. Indeed, these BSFs are characterized by an irregular distribution of inherited, syn-kinematic, and post-kinematic minerals, whose study provides useful information about the temperature conditions of (de)formation, and the origin of fluids circulating within faults. We combined X-ray diffraction (XRD) analyses and polytype determinations of whole-rock and several grain-size fractions (6-10 μm, 2-6 μm, 0.4-2 μm, 0.1-0.4 μm, and
Glacier variability in the Alps during the Little Ice Age - overview on course, evidences and causes
Authors: Nicolussi Kurt
Published: March 2024

The Little Ice Age (LIA) was originally understood as a period of increased glaciation in the late Holocene. Today, the term is used to describe the multi-centennial glacier advance and maximum level period in the last millennium, but it is also used to refer to the contemporaneous cooler climatic conditions beyond glaciated areas.Glacier dynamics in the Alps during the last centuries of the LIA are especially known from historical documents, i.e., written and pictorial sources, which essentially date from around 1600 CE and cover some well-known glaciers. Today, these data are enhanced in particular by tree-ring analyses on remnants of trees buried during glacial advances, which can provide calendar dates for advances and glacier maxima, also for the early centuries of the LIA. Moreover, our knowledge of the LIA period is increasingly enhanced by regional climate reconstructions and analyses on climate forcings.The LIA in the Alps can be defined as the period between the onset of climate cooling, which led to a first LIA-type maximum of glaciers, and the last LIA maximum level generally observed around the middle of the 1800s, i.e., between 1260 and 1860 CE. The first LIA-type maxima are demonstrable for the 1300s, around 1320 and 1380 CE, and then further, often seven maxima for the period ca. 1600-1860 CE. Accordingly, and taking into account the climatic variability, the LIA can be divided into an early (ca. 1260-1380), intermediate (ca. 1380-1575) and main phase (ca. 1575-1860 CE).Compared to the preceding period of the Medieval Climate Anomaly, reconstructions demonstrate increased climatic variability for the LIA, marked by repeated and pronounced cooling phases that finally triggered the glacier advances. These climatic disturbances correlate remarkably directly with significant volcanic eruptions or phases of increased volcanic activity and, albeit less clearly, with periods of reduced solar insolation, which can be derived from reduced solar activity. Distinctive and historically documented glacier advance phases are often correlated with climatic disturbances following major volcanic eruptions, e.g., the advance period around 1820 CE is following the preceding volcanic events of 1809 and 1815 CE.Today, the LIA is not only the coolest multi-centennial period of the last 10,000 years but also the reference period for assessing the changes from a system of climate and glacier variability largely determined by natural factors to an environmental system clearly shaped by human activities.
Investigation of diurnal/nocturnal and seasonal effect of blue and green features on thermal exposure in Czech cities
Authors: Lehnert Michal , Květoňová Veronika , Koukalová Alena , Jurek Martin , Geletič Jan
Published: March 2024

Increasing intensity, frequency, and duration of hot extremes has been one of the most pronounced aspects of climate change in Central Europe. At the same time cities and towns, where the majority of the population live, are affected by added urban heat load. Such circumstances require effective adaptation of the municipalities to heat extremes. On that account, the influence of blue and green features and various surfaces on thermal exposure, represented by MRT and physiological indices of Universal Thermal Climate Index (UTCI) and Physiological Equivalent Temperature (PET), has been investigated over a period of five years in a set of short-term measurement campaigns in several Czech cities. The results showed that trees in open public areas of Czech cities lead to a substantial decrease of thermal exposure during the daytime whereas it might slightly increase on-site thermal exposure during the night. Maintained turfs in open areas characteristically reduce thermal exposure only slightly, depending on grass height and density and soil properties. Similarly, the cooling or warming effect of blue elements differs with their character. The effect of fountains and misting systems in open areas of thermal exposure is usually hardly detectable; however, ground-based fountains moisturising the pavement seem efficient. Further results from a recently launched measurement winter season campaign are expected soon. 
A comprehensive method based on machine learning schemes in predicting river flow, case study: Po River
Authors: Golmohammadi Golmar , Razdar Babak , Mohammadi Kourosh , Grossi Giovanna , Javadi Saman
Published: March 2024

River flow forecasting has been the focus of many researchers for many years.  The methods evolved from simple statistical methods to highly sophisticated mathematical models.  In recent years, due to the advancement of computers and artificial algorithms, new methods have become increasingly reliable and easier to use.  One of the promising artificial intelligence methods is the Extreme Gradient Boosting (XGBoost) model.  XGBoost is a scalable, distributed gradient-boosting decision tree machine learning library.  It provides parallel tree boosting and is the leading machine learning library for regression, classification, and ranking problems.  Three different algorithms of XGBoost were used in this research and the results were compared.  These algorithms were Random Search, Grid Search, and CatBoost. The proposed models were conducted in a station located Pò River basin which is the longest river in Italy, and it flows from the Cottian Alps and ends at a delta projecting into the Adriatic Sea new Venice.  The data were divided into training and validation sets.  The statistical indicators included mean square error, Nash-Sutcliffe efficiency, and mean absolute error were calculated for each set to compare the efficiency of each algorithm.  These indicators showed that XGBoost using random search algorithm had better performance, although the other algorithms were also acceptable predictions.  In general, the XGBoost model could be used as a reliable tool to forecast the river flow at locations with enough historical data.
Machine learning-based parametric post-processing of solar irradiance ensemble forecasts
Authors: Baran Sándor , Baran Ágnes
Published: March 2024

By the end of 2022, the renewable energy share of the global electricity capacity reached 40.3% and the new installations were dominated by solar energy, showing a global increase of 21.7%. Due to the high volatility of photovoltaic energy sources, their successful integration into the electrical grid requires accurate short-term power forecasts. These forecasts are obtained from the predictions of solar irradiance, where the most advanced method is the probabilistic approach based on ensemble forecasts.  However, ensemble forecasts are often underdispersive and subject to systematic bias. Hence, they require some form of statistical post-processing, where parametric models provide full predictive distributions of the weather variables at hand.We propose a general two-step machine learning-based approach to calibrating ensemble weather forecasts, where, in the first step, improved point forecasts are generated, which then together with various ensemble statistics serve as input features of the neural network estimating the parameters of the predictive distribution [1]. In a case study based on global horizontal irradiance forecasts of the operational ensemble prediction system of the Hungarian Meteorological Service, the predictive performance of this novel method is compared with the forecast skill of the raw ensemble and the state-of-the-art ensemble model output statistics approaches [2]. We show that at least up to 48h, statistical post-processing substantially improves the predictive performance of the raw ensemble for all forecast horizons considered; the maximal gain e.g. in terms of the mean continuous ranked probability score is above 20%. Furthermore, the proposed two-step machine learning-based approach outperforms in skill its competitors.References1.  Baran, Á, Baran, S., A two-step machine-learning approach to statistical post-processing of weather forecasts for power generation.   Q. J. R. Meteorol. Soc. (2023), doi:10.1002/qj.4635.2.  Schulz, B., El Ayari, M., Lerch, S., Baran, S., Post-processing numerical weather prediction ensembles for probabilistic solar irradiance forecasting. Sol. Energy 220 (2021), 1016-1031.*Research is supported by the Hungarian National Research, Development and Innovation Office under grant no. K142849
Quantifying Soil Quality in Dryland Regions as A Key Step in Phosphate Mining Restoration
Authors: Paz-Kagan Tarin , Karnieli Arnon , Ziv Yaron
Published: March 2024

Mining is crucial in driving economic development but entails extensive environmental damage, such as soil degradation and water and air pollution. Mining activity impacts the soil quality, often making it unable to support ecosystem function and structure and reducing its ecological resilience. Soil degradation reduces physical, chemical, and biological (PBC) soil properties. The current study aims to apply the soil quality index (SQI) to quantify soil restoration success in an open-pit phosphate mine in Israel’s hyper-arid environment. In this regard, we evaluated an ecological restoration practice that includes topsoil refilling compared to the adjacent undisturbed natural system. We used transformed and standardized scorings of 11 PBC soil properties that were further statistically integrated into overall SQI values. Our results revealed significant differences between the restoration practice areas and the nearby natural areas, with a higher soil quality value in the latter. It is proposed that the topsoil restoration method is mainly affected by soil biological indicators, such as soil organic matter, soil proteins, and polysaccharides related to biocrust development, and, to a lesser extent, by physical properties (primarily infiltration rate, followed by available water content). The former properties encourage the biocrust establishment, which is essential for soil surface stabilization. This, in turn, affects the water infiltration, nutrient availability, and erosion rates. The chemical indicators showed no significant differences between most sites for the overall soil quality. In conclusion, our results reflect a slow recovery of the SQI in the restored sites, demonstrating that achieving the quality of the natural areas requires a long-term recovery process. Moreover, the physio-biological indicators were more suitable for reliably estimating mining restoration practices in dryland areas. Our approach could have broader implications for evaluating the ecological restoration success in hyper-arid environments.