bluuebunny/crossref_metadata_2025 huggingface dataset:
Koopman operator theory for enhanced Pacific SST forecasting
Authors: Lorenzo Sánchez Paula , Newman Matt , Navarra Antonio , Albers John , Subramanian Aneesh
Published: March 2024

El Niño-Southern Oscillation (ENSO) is a complex climatic phenomenon with significant impacts on global weather patterns and ecosystems. Improving ENSO predictability is therefore an issue of high societal value. However, Global Circulation Models present severe biases when predicting ENSO, and their skill remains comparable to that of vastly simpler empirical models such as Linear Inverse Models (LIMs). LIMs, however, rely on linear dynamics, and they have inherent limitations in capturing the behavior of non-linear phenomena. In this context, Koopman operator theory has emerged as a powerful mathematical framework, offering a novel perspective for analyzing complex non-linear systems, such as ENSO. In this study, we investigate the potential of Koopman operator theory to enhance ENSO forecasting accuracy. Leveraging 2000 years of tropical SST pre-industrial CESM data, we have assessed the skill of the Niño 3.4 index forecasts using the Koopman framework, and compared it to the benchmark set by LIMs. Our analysis includes sensitivity testing of both methods across various parameters, such as retained variability and data length used for operator computations. Our findings reveal nuances in the robustness of Koopman Operator estimates, particularly evident when using shorter training periods, contrasting with more stable LIM counterparts. However, a notable breakthrough emerges as we demonstrate the higher skill of Koopman multimodel ensembles, showcasing consistent improvements over linear models. The comparative analysis highlights the potential of Koopman operator theory in advancing ENSO forecasting beyond linear models. The utilization of Koopman multimodel ensembles emerges as a promising strategy, demonstrating enhanced forecasting capabilities. Yet, challenges in robustness persist, particularly in shorter data spans, signaling avenues for further refinement. Overall, these findings underscore the significance of the Koopman framework and lay the groundwork for future research aimed at refining methodologies for more accurate predictions in complex climatic systems.
A novel multivariate drought severity index: study of short-term hydrological signals within Amazon river basin
Authors: Lenczuk Artur , Ndehedehe Christopher , Klos Anna , Bogusz Janusz
Published: March 2024

The pace of Earth’s climate warming obviously sped up, especially after 2000s. Droughts are increasingly becoming  frequent, longer and more severe, with lasting impacts on ecosystems, communities and people. Thus, addressing the problem of monitoring global (or regional) climate trends and  water storage changes is crucial. We propose a novel Multivariate Drought Severity Index (MDSI) estimated through the concept of Frank copulas that is based on DSIs determined from satellite-based geodetic data. The new multivariate approach is based on data provided by the Global Positioning System (GPS) and the Gravity Recovery and Climate Experiment (GRACE).In this study, we analyze short-term (
Assessing the Ecotoxicological Risks of Heavy Metals in Contaminated Sites Using the Life Cycle Impact Assessment Method
Authors: Jeong Seung-Woo , Gautam Prakash , Kim Songhee , An Youn-Joo , Hyun Seunghun , Hong Sunhee
Published: March 2024

Heavy metal pollution has a detrimental impact on both the ecosystem and human health. In order to accurately assess the risk of contamination at a site, it is necessary to conduct sampling and ecological investigations on site, followed by laboratory analysis of contamination concentrations and toxicity. This process also requires the use of various experimental equipment and materials for ecological risk assessment. This study proposes a method for assessing ecological risks at metal-contaminated sites using life cycle impact assessment (LCIA) approaches. LCIA quantifies environmental impacts by multiplying mass-environmental loads with impact characterization factors (CF). This study aimed to develop exposure and effect factors in order to obtain site-specific CFs for metal soil contamination. The ecological risks at two mine sites were then estimated solely based on soil metal concentrations. These estimated risks were compared between sites and with detailed ecological risk results obtained using the TRIAD method. The estimated results were found to be in good agreement with the actual experimental results. This method has the potential to save time, resources, and effort in assessing the ecological risks of metal-contaminated sites. (This work was supported by the Korea Environmental Industry and Technology Institute (KEITI) funded by the Korea Ministry of Environment (No. 2022002450002)).
Vertical transport of ultrafine particles and turbulence evolution impact on new particle formation based on tower observation
Authors: Wu Hao
Published: March 2024

Ultrafine particles (UFPs) are ubiquitously distributed throughout the global atmosphere. Their dimensions, often less than 100 nm, vary significantly from the surface. New particle formation (NPF) is a key process occurring in the planetary boundary layer (PBL). Newly formed particles are an important source of aerosols and cloud condensation nuclei (CCN) that influence clouds and climate, while the distribution of these new particles at different altitudes has rarely been studied. In-situ measurements of ultrafine particles (UFP) and New particle formation (NPF) observed at the ground and at the top of the Canton Tower (454 m) and Shenzhen tower located in southern China,both were analyzed using the measurements of multiple meteorological and physicochemical quantities, as both observed during a field campaign and simulated with the WRF-chem model. We found that turbulence and NPF characters vary considerably with heights, with UFP concentration diminishing by half from the surface to the tower top. This indicates the UFP transports upward from the ground in the lower boundary layer. A consistent relationship is established between the occurrences of NPF and the evolution of turbulence. The correlation between the exchange ratio at the tower top has correlated well with nucleation growth, suggesting that turbulence can play an important role in the episodes of NPF growth, whose growth rate is closely related to the turbulence exchange ratio, effectively dictating the ultrafine particle concentration before and during the lockdown period. A new mechanism is thus hypothesized: NPF happens eailer near the surface and grows faster at the upper PBL, attributed to condensable vapors being transported by turbulent vertical mixing in the boundary layer. Model simulations using the WRF-Chem model reveal that the exchange ratio changed the NPF parameters, supporting the proposed mechanism that the evolution of the PBL variation has a significant impact on NPF, which should not be omitted in the NPF research, since this physical factor could be a dominant one in the NPF mechanism.
Revealing 3D Variations in Forest Fuel Structures in Subtropical Forests through Backpack Laser Scanning 
Authors: Li Shun , Wu Zhiwei , Huang Chao
Published: March 2024

Wildfire hazard is a prominent issue in subtropical forests as climate change and extreme drought events increase in frequency. Stand-level fuel load and forest structure are determinants of forest fire occurrence and spread. However, the current fuel management often lacks the detailed vertical fuel distribution, limiting accurate fire risk assessment and effective fuel policy implementation. In this study, backpack laser scanning (BLS) is used to estimate several 3D structural parameters, including canopy height, crown base height, canopy volume, stand density, vegetation area index (VAI) and vegetation coverage, to characterize the fuel structure characteristics and the vertical density distribution variation in different stands of subtropical forests in China. Through standard measurement by BLS point cloud data, we found that canopy height, crown base height, stand density, and VAI in the lower and middle height strata differed significantly among stand types. Comapre to vegetation coverage, LiDAR derived VAI can better show significant stratified changes in fuel density in the vertical direction among stand types. Among the stand types, conifer-broadleaf mixed forest and C. lanceolata had higher VAI in surface strata than other stand types, while P. massoniana and conifer-broadleaf mixed forests were particularly unique in having higher VAI in the lower and middle height strata, corresponding to the higher surface fuel and ladder fuel in the stand respectively. To provide more informative support for forest fuel management, BLS LiDAR data combined with other remote sensing data was advocated to facilitates the visualization of fuel density distribution and the development of fire risk assessment. 
Assessing the Impact of Enhanced Rock Weathering on Soil Biological Interactions with Comprehensive Carbon Dioxide Removal Index
Authors: Ok Yejee , Hyun Junge , Park Ye Lim , Yoo Gayoung
Published: March 2024

Enhanced Rock Weathering (ERW) is emerging as a promising Carbon Dioxide Removal (CDR) strategy. While existing research predominantly measures dissolved inorganic carbon (DIC) and soil inorganic carbon (SIC) to evaluate CDR effects, the significance of plants and their influence on soil organic carbon (SOC) within the ERW process remains underexplored. Our study aims to investigate the impact of ERW amendments on SOC sequestration when applied to soils with planted vegetation. The variation in SOC sequestration due to ERW depends on factors such as the composition of ERW materials, soil conditions, and the presence of plants and microorganisms. Under these interactions, stable SOC storage for at least several decades needs to be considered a CDR effect, although the increase in plant growth may not be considered a CDR effect due to the short carbon storage time. Additionally, we propose the inclusion of non-CO2 greenhouse gas emissions, particularly N2O emissions resulting from microbial activity changes, in our comprehensive CDR Index. Here, we suggest a comprehensive CDR Index for ERW, encompassing direct effects on SIC and DIC, indirect impacts on SOC, and N2O fluxes. To thoroughly investigate the CDR impact of ERW materials, we assessed the CDR Index for two distinct ERW materials: natural rock and industrial by-product silicate. Our four-month pot experiment involved control and two ERW amendments(olivine and blast furnace slag) alongside two planting scenarios(with alfalfa and without plants). We hypothesize that the CDR effect calculated using our comprehensive CDR Index will differ from that calculated using only DIC or SIC measurements. We anticipate significant increases in SIC and DIC for treatments, particularly with blast furnace slag due to its composition. In the plant-involved treatments, we anticipate both higher SIC, as plants accelerate weathering with their acidic exudates, and increased SOC, indicating improved plant growth and subsequent carbon sequestration. Variations in N2O fluxes are also anticipated with different ERW amendments. Initial data from three weeks shows significant DIC increases with blast furnace slag and modest increases with olivine. Greater plant biomass was observed in treatments compared to control, suggesting varied biological impacts. Throughout the remaining four-month experiment, we aim to document changes in SIC, DIC, SOC, and differences in N2O fluxes. These results are anticipated to vary based on the type of amendment and the planting options. This research is expected to underscore the significance of the biological effect in a comprehensive CDR assessment and contribute to identifying the most effective conditions for CDR with ERW when considering biological impacts. The findings are expected to guide future research and the implementation of ERW strategies, contributing to global climate change mitigation efforts.
Identifying crop heat stress with MODIS and FLUXNET data
Authors: Lai Peiyu , Marshall Michael , Darvishzadeh Roshanak , Tu Kevin , Nelson Andrew
Published: March 2024

Stress caused by high temperatures is a critical limiting factor of crop growth and development. Accurately identifying heat stress is crucial to assess and mitigate the negative impact of high temperatures on crop growth. However, isolating the independent effects of heat stress from other factors, such as moisture stress, poses a challenge in field conditions. This study developed an innovative approach to distinguish crop heat stress periods from normal growth conditions, disentangling them from moisture stress and light limitation in croplands. Utilizing FLUXNET data, including air temperature, gross primary productivity, soil water content, and shortwave radiation observations, we identified 78 heat periods and corresponding normal growth conditions. The identified heat and normal periods were further related with remote sensing to extend the identification process to a large scale. Single bands and spectral vegetation indices (VIs) derived from MODIS were employed to evaluate the capability of multispectral data in detecting heat stressed crops from healthy crops. The analysis revealed a significant increase in the reflectance of red band during heat stress. VIs, in general, enhanced the visibility of heat-induced spectral variations and exhibited sufficient capability in distinguishing crops at heat and normal conditions. Visible bands-based indices (EVRI, GLI, and NGRDI) exhibited the highest distinguishability (p-value < 0.01 in the Mann–Whitney U test). These findings underscore the significance of visible bands, especially the red band, in advancing large-scale crop heat stress detection, agricultural monitoring, and crop modeling considering heat stress.
Intraseasonal Variability of Anticyclonic Rossby Wave Breaking and Its Impact on Tropical Cyclone Activity over the Western North Pacific
Authors: Qian Yitian , Hsu Pang-chi , Murakami Hiroyuki , Zhang Gan , Wang Huijun , Duan Mingkeng
Published: March 2024

The intraseasonal variations in anticyclonic Rossby wave breaking (AWB) events, which are characterized by synoptic-scale irreversible meridional overturning of potential vorticity over the North Pacific, and their modulations on tropical cyclone (TC) activity over the western North Pacific (WNP), were investigated in this study. Spectral analysis of the AWB frequency shows significant variability within a period of 7–40 days, closely linked to the subseasonal variability of the jet stream intensity. When the jet stream weakens at its exit region over the North Pacific, the AWB occurs along with an equatorward Rossby wave flux. This AWB is preceded by an intensified Rossby wave train across Eurasia 12 days earlier. Simultaneously, a high potential vorticity intrusion is advected in the upper troposphere from the North Pacific toward the WNP, and suppressed TC activities are observed over the WNP open ocean where decreased moisture and temperature, subsidence, and increased vertical wind shear prevail. In contrast, anomalously enhanced convection, positive relative vorticity, and ascending motion are found in the southwestern quadrant of the AWB, facilitating enhanced TC activities over the South China Sea (SCS). Further analysis indicates that the impact of the AWB on TC activities over the WNP is robust and independent of the tropical intraseasonal convection over the tropical Indian Ocean and SCS, even though it accompanies the increased AWB frequency.
Quantifying spatiotemporal variations of cropland phosphorus runoff loss in China with machine learning algorithms
Authors: Pan Zheqi
Published: March 2024

    Excessive applications of phosphate fertilizers have led to significant phosphorus (P) accumulation in agricultural soils. This surplus P is prone to being lost through surface runoff, thereby threatening downstream water bodies such as aquifers, streams, lakes, and oceans. Indeed, the runoff loss of P has led severe global environmental concerns, including proliferation of harmful algal blooms, onset of eutrophication, and expansion of anoxic dead zones in coastal marine ecosystems. Assessing the spatial distribution of total P (TP) runoff loss from croplands is essential for developing targeted mitigation strategies against the persistent issue of nonpoint source pollution. In this study, we compiled 812 datasets from 114 peer-reviewed papers for cropland P loss across China. We then developed machine learning (ML) approaches to estimate the temporal and spatial variations in P runoff loss across China from 1990 to 2020. Four prevalent ML models were considered, namely, multiple linear regression (MLR), random forest (RF), classification and regression trees (CART), and boosted regression trees (BRT). Among these four models, RF exhibited the highest predictive accuracy for both uplands (calibration: R2 = 0.86, n = 293; validation: R2 = 0.61, n = 96) and paddy fields (calibration: R2 = 0.88, n = 137; validation: R2 = 0.60, n = 44). According to RF, China’s croplands are estimated to have lost an average of 148 ± 27 Gg P yr⁻¹ from 1990 to 2020, with uplands and paddy fields contributing 114 ± 26 Gg P yr⁻¹ and 34 ± 4 Gg P yr⁻¹, respectively. The data showed a significant increase in upland TP runoff loss over the study period (p
Water vapor adsorption and flow dynamics in dry desert soils
Authors: Kool Dilia , Agam Nurit
Published: March 2024

Water vapor adsorption is the least studied form of non-rainfall water inputs but is likely the most common one in arid and hyper-arid areas. It is determined by the magnitude of the downward gradient in water vapor pressure between the atmosphere and the soil; the surface area of the adsorbing soil; and the penetration depth of water vapor adsorption. Water vapor adsorption was measured using micro-lysimeters and profiles of relative humidity (RH) sensors in both loess and sand in the Negev desert, Israel, over the summers of 2021 and 2022. The RH sensor array allowed measurement of detailed changes in water content in the soil profile and provided an unprecedented insight into processes governing water vapor adsorption dynamics under arid conditions in-situ. The RH sensors significantly underestimated total water vapor adsorption, indicating that a finer array is needed to capture the full process. However, even with the current array, extremely small changes in water content were captured. With these measurements we explored the three main factors contributing to water vapor adsorption. The onset of a downward vapor pressure gradient coincided with the arrival of the sea breeze, indicating that the sea breeze is the primary source for water vapor adsorption in the uppermost soil layer. Water vapor adsorption was higher in loess than in sand, due to its finer texture and larger surface area. The most important finding of this research is that the dominant mechanism for water vapor flow under natural arid conditions (relative humidity in the soil (RHs)
Future changes in hydropower energy system in the Yangtze River Basin under different warming levels
Authors: Liu Xinyue , Yuan xing
Published: March 2024

In comparison to traditional fossil fuels, hydropower has the potential to significantly reduce greenhouse gas emissions and play a crucial role in promoting a low-carbon energy structure transformation. However, the reliability and stability of the hydropower system in the warming future remain unclear. Here, we evaluate the impact of future climate change on hydropower production, regional electricity demand, and energy system supply-demand balance in the Yangtze River Basin (YRB), which is China's largest hydropower production base. We have utilized two indexes, i.e., Energy Production Drought (EPD) and Energy Supply Drought (ESD), to characterize the changes in the hydropower energy system. EPD refers to a series of days with low hydropower production, while ESD refers to a series of days with mismatched production/demand. We utilize 15 global climate models from CMIP6 to force the Conjunctive Surface-Subsurface Process version 2 (CSSPv2) land surface model with consideration of reservoir regulations, to estimate the generation capacity of 86 mainly hydropower plants in YRB. In addition, an empirical electricity demand model considering socio-economic and climate factors is adopted to evaluate the changes in electricity demand in the receiving areas of southern China. Under climate change, the projected hydropower generation in the YRB is expected to increase throughout the 21st century. However, the future electricity demand will also rise due to GDP growth. Climate change will alter the distribution of seasonal electricity demand, resulting in an increasing mismatch between electricity demand and hydropower supply. Therefore, hydropower EPD and ESD are also being investigated, and the study is crucial for understanding future changes in the electricity supply and demand balance, as well as mitigating the impact of global warming.
FLEXPART-11: Advancements in a Lagrangian Atmospheric Model for Enhanced Accuracy, Efficiency, and Flexibility
Authors: Bakels Lucie , Tatsii Daria , Tipka Anne , Dütsch Marina , Blaschek Michael , Bucci Silvia , Plach Andreas , Vojta Martin , Seibert Petra , Pisso Ignacio , Eckhardt Sabine , Cassiani Massimo , Groot Zwaaftink Christine , Mulder Marie , Stohl Andreas
Published: March 2024

Numerical methods and advanced simulation codes play a crucial role in helping us understand complex atmospheric processes. As technology progresses, it's important to develop sophisticated code for accurate and efficient simulations. In this update to FLEXPART, a Lagrangian model used in numerous studies for the past 30 years, we've made significant improvements. This version of FLEXPART shows improvements in accuracy and computational efficiency. By using native ECMWF coordinates, we reduced conservation errors by about 8-10% for semi-conserved quantities like potential vorticity. The shape of aerosol particles are now properly accounted for, greatly improving the accuracy of the deposition of non-spherical particles (e.g. microplastic fibers). Additionally, the incorporation of OpenMP parallelisation makes the model better suited for handling large input data and extended simulation periods. We've also introduced new methods for the input and output of particles in FLEXPART. Users can now run FLEXPART with their own particle input data, making it more adaptable for specific research scenarios.
Lag times and flow pathways of New Zealand's river catchments: Developing robust national scale metrics using stable isotopes  
Authors: Dudley Bruce , Hill Alice , McKenzie Andy , Yang Jing
Published: March 2024

Sub-surface flow pathways and transit times of water to rivers are vital catchment characteristics that determine how climate change and land use affect surface water quality and runoff amounts. These catchment characteristics also determine the appropriateness of catchment scale management decisions to control water quality and runoff.Conservative hydrologic tracers remain reliable, accurate tools to partition river flows among flow pathways, and calculate transit times. For example, hydrogen (H) and oxygen (O) stable isotopes provide the data for robust calculation of the young (less than a few months old) fraction of river flow. H and O isotopes also have the potential to be integrated into the next generation of 'isotope-enabled' hydrological models, which are designed to provide accurate flow-source partitioning and flow estimates outside the range of historical climate conditions.Currently, the use of H and O stable isotopes as hydrologic tracers in large catchment scale hydrology across New Zealand is hindered by the requirement for extensive, non-routine sampling. To lower this hurdle, we have prepared national databases of precipitation and river water isotope data, and developed national-scale, time varying isotope models (isoscapes).      Here, I describe our development of precipitation and river isoscapes for New Zealand, and initial calculations of young water fractions across New Zealand rivers.Database development used a combination of regional government, research and citizen science collections. Our databases now include regular long-term (>18 months) sampling from around 100 rivers, and over 100 precipitation sites nationally.Using these databases, we have developed isoscapes using a range of statistical modelling techniques.  Sinusoidal precipitation isoscape results suggest that strong seasonal cycles of precipitation stable isotope values in some areas of New Zealand (but not others) are conducive to calculation of young water fractions for rivers and may require consideration for interpreting sources of recharge to groundwater and river water. Our machine-learning precipitation isoscape captures much of the non-seasonal temporal variation that dominates in windward areas of New Zealand. These results have wider implications for the application of stable isotopes as hydrological tracers in regions with mixed marine- and continental-type climates.Results indicate that precipitation isoscapes can now be combined with regular river sampling to provide robust comparisons of young water fractions at a regional level.
Towards a coupled crop-climate seasonal prediction system for dry-land wheat grain yield in Israel
Authors: Strobach Ehud , Ben-David Roi , ray Avimanyu , Menachem Yotam
Published: March 2024

Wheat production accounts for the largest portion of agricultural land in Israel, and it is the 2nd most productive crop worldwide after Maize. Spring wheat which is mostly grown under rain-fed conditions, is highly susceptible to changes in climate conditions. As a result, wheat grain yields (GY) are suffering from high climate-dependent year-to-year variability, particularly under changes in precipitation patterns. This large variability stresses the need for accurate seasonal predictions of wheat yield, which may assist farmers in better agro-system planning, making the right management decisions (crop rotation, sowing dates and application of irrigation), and the right varietal choice. As a widespread crop, wheat also has the potential to impact regional climate conditions through an interactive feedback loop by exchanging heat and water with the land surface and the atmosphere above. Yet, current seasonal crop yield prediction systems do not account for climate-crop feedback, and their prediction skill is lacking.The current study hypothesizes that using a high-resolution regional climate model (WRF) coupled with a crop model (Noah-MP-Crop) may increase seasonal crop yield prediction skill, providing a practical tool for farmers to increase their revenues and increase food security. To confirm this hypothesis, we have adapted the Noah-MP-Crop model for the spring wheat cultivars grown in Israel and conducted coupled simulations using the updated observed crop model parameters. In this presentation, the in-situ calibration process of the crop model to the spring wheat cultivars grown in Israel will be presented together with several simulated results from the calibrated coupled crop-climate model. A focus will be put on the exchange of heat, water, and carbon between the land surface and the lower atmosphere.
An Evaluation of Solar Irradiance Projected by CMIP6 Models Toward Long-Term Projection of Climate Change
Authors: Kim Chang , Kim Hyungoo , Kim Jin Young
Published: March 2024

This study assesses the reliablity of CMIP6 models in projecting solar irradiance, a crucial aspect of climate dynamics. While extensive scrutiny has been given to historical data from 1975 to 2000, our primary focus is directed towards assessing the models' performance from 2010 to 2020 and their predictive efficacy for the future. Through a meticulous methodology involving statistical comparisons, validation against measurements, and consideration of external factors, we found that CMIP6 models commendably aligned with observed solar irradiance during the historical period, showcasing their adeptness in replicating past climate conditions. However, an in-depth analysis of the recent decade unveiled deviations from observed solar irradiance, prompting concerns regarding the models' adaptability to the swift pace of contemporary climate change. Shifting our gaze to the prospective view, we explore the models' robustness in adapting to emerging climatic trends and emphasize the necessity of continuous refinement, incorporation of real-time data, and a comprehensive understanding of external factors to enhance accuracy in future predictions. Rapid climate change introduces uncertainties such as aerosol concentrations, greenhouse gas emissions, and solar variability, posing challenges that necessitate constant model adjustment. The implications for climate change mitigation are significant, as reliable solar irradiance predictions inform decisions on renewable energy adoption, agriculture planning, and climate adaptation measures. In conclusion, this study bridges the gap between historical evaluations and future projections, providing valuable insights for policymakers, researchers, and stakeholders invested in mitigating the impact of climate change. Continuous refinement of CMIP6 models and a holistic approach to understanding external factors are crucial for building a robust foundation in addressing the challenges posed by climate change in the coming decades.
Electron Scale Coherent Structure as Micro Accelerator in the Earth’s Magnetosheath
Authors: Xie Zikang , Zong Qiu-Gang , Yue Chao , Zhou Xu-Zhi , Liu Zhi-Yang , He Jian-Sen , Hao Yi-Xin , Ng Chung-Sang , Zhang Hui , Yao Shu-Tao , Pollock Craig J. , Le Guan , Ergun Robert E. , Lindqvist Per-Arne
Published: March 2024

Turbulent energy dissipation is a fundamental process in plasma physics that has not been settled. It is generally believed that the turbulent energy is dissipated at electron scales leading to electron energization in magnetized plasmas. Here, we propose a micro accelerator which could transform electrons from isotropic distribution to trapped, and then to stream (Strahl) distribution. From the MMS observations of an electron-scale coherent structure in the dayside magnetosheath, we identify an electron flux enhancement region in this structure collocated with an increase of magnetic field strength, which is also closely associated with a non-zero parallel electric field. We propose a trapping model considering a field-aligned electric potential together with the mirror force. The results are consistent with the observed electron fluxes from ~50 eV to ~200 eV. It further demonstrates that bidirectional electron jets can be formed by the hourglass-like magnetic configuration of the structure.
Modelling and Measurement of Radon and CO2 Release from Thawing Permafrost Caused by Climate Change
Authors: Glover Paul
Published: March 2024

Thawing of permafrost due to climate change is known to release gases such as the climate drivers carbon dioxide and methane, as well as the carcinogen radon. Radon is a natural radioactive gas responsible for about 10% of lung cancer deaths globally, and substantially greater rates in sub-Arctic communities. Gas transport is significantly reduced in permafrost, but now that permafrost is thawing due to climate change, the effect on the release of CO2 and CH4, and on domestic radon exposure is unknown.Measurement: Few experimental measurements have shown the gas permeability of permafrost to be very small (order of 10-16 m2). Here we present the initial measurements of the changes in porosity and gas permeability during the thawing of synthetic permafrost using a pyknopermeameter that we are developing. The results show increases in gas permeability by many orders of magnitude, that remain during freeze-thaw cycles providing the thawed water does not drain from the sample. Draining the thawed water leads to compaction which decreases the effects of subsequent thawing on the matrix gas permeability, but can cause fracturing which provide high permeability pathways for gas flow.Modelling: Results from radon transport modelling through soil, permafrost, and model buildings either with basements or built on piles show that permafrost acts as an effective radon barrier, reducing radiation exposure to a tenth of the background level in dwellings while producing a ten-fold increase in the radon activity below the permafrost. When we model thawing of the permafrost barrier, we find no increase in radon to the background level for buildings on piles.  However, for buildings with basements, the level of radioactivity due to the radon increases to over one hundred times its initial value and can remain above the 200 Bq/m3 threshold for up to 7 years depending on the depth of the permafrost and the speed of thawing. When thawing speed is taken into account, radiations remain higher than the threshold for all scenarios where 40% thawing occurs within 15 years. This new information suggests that the sub-Arctic population could be exposed to dangerous radon levels as a result of climate change.
Dust particles as a supportive environment for biofilm-forming prokaryotes
Authors: Lang-Yona Naama
Published: March 2024

Airborne microorganisms (bioaerosols), traveling across long distances, can significantly affect ecosystems, biogeochemical cycles, and human health. Dust events are a major source of bioaerosols, contributing to their global dispersion. Due to climate change-driven desertification and land-use changes, these events are projected to increase in intensity and frequency. Therefore, the transport of microorganisms over dust is expected to become more prominent. Hence, it is essential to understand the mechanisms allowing dust-borne microorganisms to survive in their atmospheric journy. Here we will present our findings on the impact of dust origins, meteorological conditions as well as diurnal sampling time on the microbial community composition and bioactivity through high throughput sequencing analysis. Our results show connectivity between bioactive groups. We will also present our findings on the distinctive characteristics of dust-borne prokaryotes isolated from dust events, showcasing diverse spore-forming bacteria with biofilm formation abilities. These findings indicate their possible preferential survival over dust, and open new paths to better understanding the survival strategies of dust-borne microorganisms.
Grand designs: quantifying many kinds of model uncertainty to improve projections of sea level rise 
Authors: Edwards Tamsin , Turner Fiona , Rougier Jonathan , Rohmer Jeremy ,   EU PROTECT project
Published: March 2024

In the EU Horizon 2020 project PROTECT, we have performed around 5000 simulations of the Greenland and Antarctic ice sheets and the world’s glaciers to predict the land ice contribution to sea level rise up to 2300. Unlike previous international model intercomparison projects (Edwards et al., 2021; IPCC Sixth Assessment Report, 2021), this is a "grand ensemble" sampling every type of model uncertainty – plausible structures, parameters and initial conditions – and is performed under many possible boundary conditions (climate change projected by multiple global and regional climate models). The simulations also start in the past, unlike the previous projects, to assess the impact of these uncertainties on historical changes.
We use probabilistic machine learning to emulate the relationships between model inputs (climate change; ice sheet and glacier model choices) and outputs (sea level contribution), so we can make predictions for any climate scenario and sample model uncertainties more thoroughly than with the original physical models. We try multiple machine learning methods that have different strengths in terms of speed, smoothness, interpretability, and performance for categorical uncertainties (Gaussian Processes, random forests).
The design of the grand ensemble allows the influence of all these uncertainties to be captured explicitly, rather than treating them as simple noise, and the earlier start date allows formal calibration (Bayesian or history matching) with observed ice sheet and glacier changes, to improve confidence (and typically reduce uncertainties) in the projections. Here we show preliminary projections for global mean sea level rise up to 2300 using these advances, and describe challenges and solutions found along the way.
Optimizing Spur Dike Orientation for Scour Control in Downward Seepage Scenarios
Authors: Patel Harish Kumar , Arora Sukhjeet , Kumar Bimlesh
Published: March 2024

In hydraulic river engineering, river bank protection is crucial to preserving natural rivers, lands, and bridges. As erosion-protective structures, spur dikes protrude outward from the riverbank in different directions to divert the flow away from the bank. The present study examines temporal variation in bed morphology and scours around rectangular-shaped spur dikes with orientations such as 60°, 90°, and 120°. In addition, the formation of maximum scour depth is compared to the condition when downward seepage is applied. The experiments investigated different configurations of spur dike orientation to assess their suitability and the scour progression over time, specifically observing intervals at 2, 12, and 24 hours and comparing them with a 24-hour duration focused on seepage. Findings indicated that a 90º orientation angle produced the most substantial scour depth, while an angle of 120º resulted in the shallowest scour depth. The downward seepage enhanced sediment particle movement, leading to increased particle detachment and deeper scour formations. Scour depth initially starts at the tip of the spur dike and reaches its maximum there. Sand particles were deposited downstream, creating a dune-like structure near the second spur dike.Keywords: Temporal scour variation, Bed morphology, Oriented spur dikes, Downward seepage.
GIS-based approach to generate the bioaccessibility of soil heavy metals for human risk assessments: case study in Changhua farmlands, Taiwan
Authors: Fan Yen-Tzu , Wang Ying-Lin , Tsou Ming-Chien , Hseu Zeng-Yei , Hsi Hsing-Cheng , Chien Ling-Chu
Published: March 2024

Considering the bioaccessibility of soil heavy metals for human health assessment can prevent overestimation for policymakers. However, the complexity of soil properties and heavy metal concentrations makes it challenging to establish a general dataset for bioaccessibility in assessments. Soil heavy metals commonly occur in agricultural regions due to both agricultural and industrial activities, posing high health risks for residents through soil exposure. In the past 10 years, the government in Taiwan has actively promoted soil remediation for agricultural heavy metal-polluted soils, completing remediation for more than 99% of polluted sites. However, conducting health risk assessments for remediated soils remains difficulty due to a lack of a general dataset for the bioaccessibility of common soil heavy metals. In this study, we conducted soil sampling from 98 sites located in agricultural regions with various soil properties. We first established regression relationships for the bioaccessibility of six common heavy metals: cadmium (Cd), lead (Pb), chromium (Cr), nickel (Ni), copper (Cu), and zinc (Zn), based on measured soil properties and heavy metal concentrations. Second, we performed GIS analysis to generate the bioaccessibility of heavy metals from a previous soil survey across all agricultural regions in Taiwan, using our established equations. Then, we conducted health risk assessments for residents at different stages of life (infants, children, teenagers, adults, and seniors) living in agricultural regions (i.e., Changhua farmlands) after soil remediation. Our results revealed high non-carcinogenic risks (hazard index > 1) for infants and children but high carcinogenic risks (total cancer risk index > 1e-4) for seniors. Our study established a GIS-based approach for estimating the bioaccessibility of soil heavy metals based on actual measurements, providing an easier way for health risk assessments of soil heavy metal pollution. Keywords: SBET, human health, farmland, heavy metal pollution, GIS
Quantitative Analysis of Electron Acceleration in Coalescing Magnetic Flux Ropes at Earth’s Magnetopause
Authors: Ma Wenqing , Zhou Meng , Zhong Zhihong
Published: March 2024

Coalescence of magnetic flux ropes (MFRs) is suggested as a crucial mechanism for electron acceleration in various astrophysical plasma systems. However, how electrons are being accelerated via MFR coalescence is not fully understood. In this paper, we quantitatively analyze electron acceleration during the coalescence of three MFRs at Earth’s magnetopause using in-situ Magnetospheric Multiscale (MMS) observations. We find that suprathermal electrons are enhanced in the coalescing MFRs than those in the ambient magnetosheath and non-coalescing MFRs. Both first-order Fermi and E acceleration were responsible for this electron acceleration, while the overall effect of betatron mechanism decelerated the electrons. The most intense Fermi acceleration was observed in the trailing part of the middle MFR, while E acceleration occurred primarily at the reconnection sites between the coalescing MFRs. For non-coalescing MFRs, the dominant acceleration mechanism is the E acceleration. Our results further consolidate the important role of MFR coalescence in electron acceleration in space plasma.
Thermo-mechanical properties and fracture behavior of granite at pore scale: implications for geological storage
Authors: Mo Chengkang , Zhao Junliang , Zhang Dongxiao
Published: March 2024

Geological storage of energy and carbon dioxide requires a deep knowledge of the complex thermo-hydro-chemo-mechanical processes that affect the stability and performance of reservoir rocks. In this study, we investigate the thermo-mechanical properties and mesoscale fracture behaviors of four key minerals in granites: quartz, plagioclase, amphibole, and biotite. We use a combination of experimental and analytical techniques to reveal the microscale mechanisms of rock failure under high temperature and tensile loading.We perform nanoindentation tests under dynamic heating–cooling cycles to measure the reduced modulus and hardness of the minerals. We also conduct mode I fracture tests under tensile loading conditions to evaluate the fracture toughness and tortuosity of the granite. We observe the dynamic crack propagation and fracture morphology of minerals using scanning electron microscopy. We analyze the structural and physio-chemical changes at high temperatures using X-ray diffraction, thermogravimetric analysis, and Fourier’s transform infrared spectroscopy.We find that the thermo-mechanical properties and fracture behaviors of the minerals are governed by three main factors: the alterations in mineral structure, the aperture of open cracks along cleavage planes, and the degree of heterogeneity due to mineral composition complexity. We identify two different damage modes in granite: catastrophic and non-catastrophic failure modes. We explain the underlying mechanisms of each mode and show that catastrophic failure has precursory signs, while non-catastrophic failure does not.Our results provide new insights into the microscale mechanisms of rock failure under high temperature and tensile loading, which have implications for the macroscopic understanding of rock behavior in geological storage applications. By elucidating the microscale intricacies, this study enhances our understanding of the multifaceted interactions that influence the stability and performance of rocks, and supports the development of improved geological storage strategies, such as carbon sequestration and enhanced energy storage.
Controls of atmospheric carbon transfer to soil by root exudates
Authors: Brunn Melanie
Published: March 2024

The interaction between plants and soil plays a decisive role in controlling the formation of soil organic matter (SOM) - a critical factor for the functioning of ecosystems and the mitigation of climate change. Carbon compounds that plants release into the soil as root exudates have important impacts on the stability of SOM and can shift with climate change. Yet, a generalizable understanding of the biotic and abiotic controls on the relationships between plant-soil carbon exchanges and large-scale carbon fluxes and SOM formation is still lacking.Here, I compile data from different forest ecosystems to illustrate: 1) the response of root exudates in distinct ecozones to species mixing, 2) the impact of drought and recovery on plant-soil interactions, and 3) the quantitative correlation between rhizodeposition and ecosystem carbon uptake, as well as its association with SOM formation.Observations point to a connection between carbon exudation and root growth, with greater root growth leading to reduced exudation rates and vice versa. However, exudation rates across diverse ecozones were highly responsive to even minor alterations in the sampling method, suggesting careful considerations when comparing datasets from different studies. The rhizosphere showed increased levels of stabilized SOM that endured after drought, suggesting the potential for rhizodeposition to enhance the preservation of soil carbon.Current data indicates that a substantial fraction of carbon in the atmosphere is allocated towards root exudates, likely serving as a crucial element in the ability of ecosystems to respond to climate change. Understanding plant-soil interactions in a global context requires aligning sampling methods within an ecozonal context.
The islanding effect of river basin city-regions under climate changes: vulnerability and resilience
Authors: Hung Chi-Tung , Lin Wen-Yen , Liu Chun-Fang
Published: March 2024

This study focusing on the vulnerability and resilience in the downstream areas of the Da-an river basin (Dajia district and Houli district) centeral Taiwan. The study addresses the urban governance on compound disaster in the upstream Da-an river basin, including Taian township and Jhunan township in Miaoli county, Zhuolan township, and the Heping district in Taichung city. The research also explores how these townships adapt to extreme weather impacts and post-pandemic industrial adaptation. Our research employs various methods such as field surveys, in-depth interviews, literature reviews, and statistical data analysis: (1) By investigating and analyzing tourism camping areas in the aforementioned townships, we examine the environmental vulnerability of their industries and land use. This includes environmentally sensitive areas and agricultural and pastoral lands in indigenous areas, as well as issues related to vulnerable policies; (2) Agricultural production and marketing and government responses to different stages of impacts from extreme climates and diseases are being reviewed regarding the adaptive planning of local governments; (3) A vulnerability assessment framework applicable to settlements in islanding areas of the upper Da-an river is constructed by utilizing the Analytic Hierarchy Process (AHP) and Geographic Information System (GIS) for overlay analysis to discuss the relevant assessment influencing factors in camping areas. The research aims to clarify how watershed townships, under the influence of climate change, transform based on local tourism characteristics and agricultural industries post-pandemic. Particularly, it explores the mitigation measures demonstrated by local governments and private operators in the face of climate change and land exposure, showcasing the resilience of governance at different levels of government and private entities. Two aspects are found on this research: (1).The tourism vulnerability of townships in the upper Da-an river basin, particularly the crisis of camping tourism sites and land exposure, along with the island effect of their settlements. (2). Adaptive mechanisms of industrial resilience in watershed townships under the impact of the pandemic.Keywords: river basin, extreme weather, islanding effect, city resilience, urban disaster, city vulnerability.