bluuebunny/crossref_metadata_2025 huggingface dataset:
Increasing hydrologic connectivity contributes to browning of northern freshwater
Authors: Basso Stefano , de Wit Heleen
Published: March 2024

Sustained increments of organic carbon concentrations in northern freshwaters have triggered concerns about the impacts of water browning and raised questions on the underlying mechanisms causing this phenomenon. In addition to the key role played by reduced sulfate deposition, hydrologic mechanisms have been put forward as possible concurrent causes of the observed trends of organic carbon concentrations. How the suggested hydrologic controls act is however still unclear. In this study we analyze long data series (> 30 years) of daily discharge and weekly to biweekly Total Organic Carbon (TOC) concentration for four reference acid-sensitive rivers in Norway, whose locations span the entire length of the country, to clarify hydrologic changes which may be promoting freshwater browning. In all cases we observe stable values of the slopes of double logarithmic relations between concentration and discharge, as well as a steady growth along the years of the intercepts of these relations. These joint observations enable sorting out previously proposed biogeochemical mechanisms for the observed trends of TOC concentrations (i.e., less sulfate deposition versus higher soil temperature). Decreasing ratios of concentration and discharge variability along the years, observed in all watersheds during the autumn season, point at growing stores of organic carbon produced in summer and suggest that the spatial distribution of the sources is becoming more homogeneous. In detail, analyses of the runoff frequency, which is typically higher in wetter and more hydrologically connected watersheds, suggest that sources are more homogeneously connected to streams than before. In fact, increasing trends throughout the years of the runoff frequency, as well as strong relations between runoff frequency and increasing concentrations of aquatic organic carbon, are detected in all cases. More connected sources together with more frequent runoff events, which multiply the chances for the organic carbon to reach streams, may hence contribute to the observed rise of organic carbon concentrations in northern freshwaters.
Collaboratively developing workflows at the BSC-ES
Authors: Montané Pinto Gilbert , Ferrer Eric , Olid Miriam , Garcia Alejandro , Bonet Genís , Mozaffari Amirpasha
Published: March 2024

At the Earth Sciences department of the Barcelona Supercomputing Center (BSC-ES) a variety of workflows are run for many different purposes like executing climate and atmospheric simulations, data downloading or performance evaluation. This implies having to deal with many different processes and time scales in different environments and machines.To help conduct all these complex tasks, the Autosubmit workflow manager is used in the whole department as a unique framework. The fact that Autosubmit has been fully developed at the BSC-ES has led to the adoption of a co-design procedure between users, workflow developers and Autosubmit developers to fulfill the day-to-day department needs. The synergy and close collaboration among them allows the workflow engineers to gather the specific user requirements that later become new Autosubmit features available to everyone. Thanks to this continuous interaction at all levels, an efficient and very adaptable system could have been achieved, perfectly aligned with the constantly evolving user needs.Here this collaborative strategy is presented from the workflow development point of view. Some real use cases and practical examples are used to show the positive impact it had in different operational and research projects, demonstrating how it can help in the achievement of high scientific productivity.
Quantifying seasonal urban NO2 emissions using satellite observations
Authors: Fioletov Vitali , McLinden Chris , Griffin Debora , Zhao Xiaoyi , Eskes Henk
Published: March 2024

The tropospheric NO2 vertical column density (VCD) values measured by the Tropospheric Monitoring Instrument (TROPOMI) were used to study the NO2 variability and estimate urban NO2 emissions for 261 major cities worldwide. The used algorithm isolated three components in tropospheric NO2 data: background NO2, NO2 from urban sources, and from industrial point sources, and then each of these components was analyzed separately. The method is based on fitting satellite data by a statistical model with empirical plume dispersion functions driven by a meteorological reanalysis. Unlike other similar studies that studied plumes from emission point sources, this study included the background component as a function of the elevation in the analysis and separated urban emissions from emissions from industrial point sources. Population density and surface elevation data as well as coordinates of industrial sources were used in the analysis. Differences between workday and weekend emissions were also studied. Urban emissions on Sundays (or Fridays for some countries) are typically 20%-50% less than workday emissions for all regions except China. No significant difference in urban emissions between seasons was found. In contrast, the background component does not show any significant differences between workdays and weekends suggesting that background NO2 has a substantially longer lifetime compared to that in the plumes. 
Personalized warnings – Swiss public’s preferences and needs 
Authors: Kuratle Lorena Daphna , Dallo Irina , Marti Michèle
Published: March 2024

There are numerous efforts globally to enhance societies’ ability to prepare for and cope with disasters triggered by natural and human-made hazards such as heatwaves, flash floods, terrorist attacks, or earthquakes. Some of these efforts aim to enhance the effect of warnings by personalizing them. By addressing individual factors such as health issues and caregiving responsibilities and including tailored behavioral recommendations, they can become more inclusive. However, the compilation of these personalized warnings requires data, which can either be generated by a (one-time) query or extracted from individuals’ digital footprints. Thereby, the following key questions arise: Is there a desire for personalized warnings? Do these warnings improve safety culture, enhancing preparedness and responses in the face of disasters? Moreover, is the public aware of the type of data required to receive such warnings?We will answer these questions by the means of a representative online survey in Switzerland with a between-subjects experiment by assigning participants to personalized heat warnings. It allows us to assess if people would like to receive personalized warnings and whether those warnings influence their intention to take protective measures and enhance inclusiveness. Further, we will analyze people’s data sharing preferences, their trust in warnings, and the influence of their online behavior (e.g., online-shopping, use of smart watches) on their preference for those warnings. Moreover, we will assess participants’ demographics to find patterns in what type of data different social groups are willing to share.In our talk, we will present the first results of this survey and discuss implications for the further development of personalized warning messages.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 10102174
Crustal fluid cycling triggers large-scale melting in Moldanubian migmatites, Bohemian Massif, Czech Republic
Authors: Alt Ina , Oliveira da Costa Elisa , Kunz Barbara , Warren Clare , Vroon Pieter Z. , Brouwer Fraukje M.
Published: March 2024

Large granitic batholiths developed in many mountain belts during the late stages of orogenesis. While current melting process research focuses on fluid-absent breakdown of hydrous minerals at amphibolite to granulite facies conditions, petrography, phase equilibrium modelling, and trace element evidence suggests that melt formation due to influx of fluids could be more widespread than previously thought. We investigate Crd bearing diatexites and Kfs bearing migmatitic paragneisses from two locations in the Moldanubian domain of the Bohemian Massif (Czech Republic) for signs of melt formation during water-fluxed or hydrous mineral breakdown melting. We use petrography of thin sections, mineral chemistry by EPMA and trace element compositions from LA-ICP-MS analysis. Samples from Nemojov consist of Crd + Bt + Plg + Qtz + Sill + Ilm ± Kfs and show signs of biotite breakdown to Kfs. It is assumed that pre-existing muscovite was consumed during water-fluxed melting and the subsequent peritectic reaction involves biotite, together with Sill, Plg, and Qtz to form Crd. Diffuse mesosome and leucosome boundaries and the absence of peritectic Kfs suggest water-fluxed melting. The Pohled sample has peritectic Kfs together with Plg + Bt + Ms + Qtz + Ilm ± Grt. This sample has a mm-sized foliation with a clear distinction between melanosome consisting of Plg+ Bt + Ms + Qtz + Ilm and the leucosome comprising Kfs + Qtz ± Grt, reflecting muscovite dehydration melting. Trace element data from both sites show significant differences in Rb, Ba, and Sr, which are dominantly incorporated in micas and feldspars. Variable Rb/Sr ratios can be an indicator for water fluxed melting: since Sr is mainly hosted in Plg and its involvement is stronger during water-fluxed melting, low Rb/Sr values (below 3.5) can be expected in Bt, Plg, and Kfs. This indicates muscovite involvement in Pohled and plagioclase-involvement in the Nemojov samples. Biotite hosts several elements such as LILE and metals like Sc, V, Cr, Co, Ni Nb, Ta, Sn, W. During melting, biotite was consumed via water fluxed melting via the reaction:Bt + Plg + Sill + Qtz + H2O --> Crd + MeltElements like Li and Be are redistributed mainly to Crd, but Rb, Cs, Ba, Sc, V, Cr, Co, Ni, Nb, Ta, Sn, and W were incorporated into the melt (assuming equilibrium between Ilm + Bt). Alkali feldspar and plagioclase have high Ba, Sr, and Pb concentrations, and Zn is enriched in plagioclase. All of this indicates fluid influx, where muscovite released Rb, Cs, and Sn that was taken up by the feldspars. On the other hand, fluid-fluxed plagioclase breakdown resulted in elevated Sr and Ba in biotite and alkali feldspar during melting reactions in Nemojov. Feldspar from Pohled similarly shows high Rb, Sn, and Cs values indicating the influence of muscovite breakdown.
Mechanisms of Tropical Pacific Decadal Variability
Authors: Capotondi Antonietta ,   CLIVAR Tropical Pacific Decadal Variability Working Group
Published: March 2024

Naturally-occurring variability in the Tropical Pacific at timescales in the 7-70 years range, defined here as Tropical Pacific Decadal Variability (TPDV), modulates ENSO characteristics and its global impacts, and is linked to the rate of change of the globally-averaged surface temperature. Thus, understanding TPDV is integral to robustly separate the forced climate response from internally-generated climate variability and thereby produce reliable projections of the tropical Pacific and global climate. Several oceanic mechanisms have been proposed to explain TPDV, including off-equatorial Rossby wave activity, propagation of spiciness anomalies from the subtropical to the tropical regions, and changes in the strength of the shallow upper-ocean overturning circulations, known as “Subtropical Cells”. However, uncertainties remain on the relative importance of these oceanic mechanisms. Another critical source of uncertainty concerns the nature and origin of the atmospheric forcing of those oceanic processes. Anomalous wind forcing could arise as a response to tropical Pacific sea surface temperature (SST) anomalies, be induced by Pacific extra-tropical influences or result from tropical basin interactions. This presentation critically reviews the nature and relative importance of the oceanic and atmospheric processes driving TPDV. Although uncertain, the tropical oceanic adjustment through Rossby wave activity is likely a dominant source of variability at decadal timescales. A deeper understanding of the origin of TPDV-related winds is a key priority for future research.
A research product for tropospheric NO2 columns fromGeostationary Environment Monitoring Spectrometerbased on Peking University OMI NO2 algorithm
Authors: Zhang Yuhang , Lin Jintai , Kim Jhoon , Lee Hanlim , Park Junsung , Hong Hyunkee , Van Roozendael Michel , Hendrick Francois , Wang Ting , Wang Pucai , He Qin , Qin Kai , Choi Yongjoo , Kanaya Yugo , Xu Jin , Xie Pinhua , Tian Xin , Zhang Sanbao , Wang Shanshan , Cheng Siyang ,   Yuhang Zhang
Published: March 2024

Tropospheric vertical column densities (VCDs) of nitrogen dioxide (NO2) retrieved from sun-synchronous satellite instruments have provided abundant NO2 data for environmental studies, but such data are limited by retrieval uncertainties and insufficient temporal sampling (e.g., once a day). The Geostationary Environment Monitoring Spectrometer (GEMS) launched in February 2020 monitors NO­2 at an unprecedented hourly resolution during the daytime. Here we present a research product for tropospheric NO2 VCDs, referred to as POMINO-GEMS. We develop a hybrid retrieval method combining GEMS, TROPOMI and GEOS-CF data to generate hourly tropospheric NO2 slant column densities (SCDs). We then derive tropospheric NO2 air mass factors (AMFs) with explicit corrections for surface reflectance anisotropy and aerosol optical effects, through parallelized pixel-by-pixel radiative transfer calculations. Prerequisite cloud parameters are retrieved with the O2-O2 algorithm by using ancillary parameters consistent with those used in NO2 AMF calculations.Initial retrieval of POMINO-GEMS tropospheric NO2 VCDs for June–August 2021 exhibits strong hotspot signals over megacities and distinctive diurnal variations over polluted and clean areas. POMINO-GEMS NO2 VCDs agree with the POMINO-TROPOMI v1.2.2 product (R = 0.98, and NMB = 4.9%) over East Asia, with slight differences associated with satellite viewing geometries and cloud and aerosol properties affecting the NO2 retrieval. POMINO-GEMS also shows good agreement with OMNO2 v4 (R = 0.87, and NMB = −16.8%) and GOME-2 GDP 4.8 (R = 0.83, and NMB = −1.5%) NO2 products. POMINO-GEMS shows small biases against ground-based MAX-DOAS NO2 VCD data at nine sites (NMB = –11.1%) with modest or high correlation in diurnal variation at six urban and suburban sites (R from 0.60 to 0.96). The spatiotemporal variation of POMINO-GEMS correlates well with mobile-car MAX-DOAS measurements in the Three Rivers’ Source region on the Tibetan Plateau (R = 0.81). Surface NO2 concentrations estimated from POMINO-GEMS VCDs are consistent with measurements from the Ministry of Ecology and Environment of China for spatiotemporal variation (R = 0.78, and NMB = –26.3%) as well as diurnal variation at all, urban, suburban and rural sites (R ≥ 0.96). POMINO-GEMS data will be made freely available for users to study the spatiotemporal variations, sources and impacts of NO2.
Flark area monitoring in boreal aapa mires using multi-resolution optical remote sensing
Authors: Keränen Kaapro , Isoaho Aleksi , Räsänen Aleksi , Hjort Jan , Kumpula Timo , Korpelainen Pasi , Rana Parvez
Published: March 2024

Peatlands have globally suffered significant degradation due to human activities which has necessitated monitoring of the condition of and changes in peatland ecosystems. With remote sensing, point-based in-situ observations can be upscaled to larger areas but there is a need to develop scalable monitoring methods. We hypothesize that the upscaling can be conducted by combining multispectral uncrewed aerial vehicle (UAV) and optical satellite imagery observations. We tested the hypothesis in predicting wet flark area extent, a key ecological indicator for patterned aapa mires with flarks, in five sites in central Finland. We asked: 1) How does the spatial and spectral resolution of widely used optical satellite image sensors (Landsat 8-9, Sentinel-2, and PlanetScope) influence flark area coverage prediction? 2) Are there seasonal and site-specific differences in prediction accuracy? 3) Is it feasible to upscale flark area coverage to larger mire areas? We employed UAV-derived flark area classification as a ground reference to compare predictive accuracy of satellite imagery data. We predicted flark area coverage using spectral bands and indices as explanatory variables in random forests regressions. Our findings revealed that all sensors provide accurate results, but there were differences in explanatory capacities between Landsat (pseudo-R² 32−84%, root-mean squared error (RMSE) 10−18%), Sentinel-2 (R² 61−92%, RMSE 6−14%), and PlanetScope (R² 46−92%, RMSE 6−17%) data. The shortwave infrared bands of Landsat and Sentinel-2 did not increase the prediction accuracy. There were notable site-specific variations in prediction accuracy despite all the sites having typical aapa mire wet flark–dry string patterns. With single-site models the prediction accuracies were similar for early and late summer conditions, but when transferring the models to the other sites, performance decreased considerably, especially with the models constructed with the late-summer imagery. Finally, we successfully upscaled the single-site models to detect flark area coverage across entire mire areas. Our results demonstrated that UAV-satellite image combination can be used to track key indicators of peatland conditions and monitoring changes in them.
Diurnal variations in greenhouse gas emissions from two contrasting thermokarst lakes in Nunavik, Canada
Authors: Pouliot Amélie , Nadeau Daniel , Laurion Isabelle
Published: March 2024

Small thermokarst lakes, formed by the thawing of ice-rich permafrost, can emit significant amounts of methane (CH4) and carbon dioxide (CO2) to the atmosphere. The physical processes behind diurnal variations in greenhouse gas (GHG) emissions from thermokarst lakes remain poorly understood due to a lack of observational data in subarctic regions. This study focuses on the dynamics of GHG emissions from two small lakes (< 200 m2) located in the Tasiapik Valley, near the village of Umiujaq, Nunavik, Canada (56°33'28.8"N 76°28'46.5"W). One lake is characterized by a more humic and sheltered environment, while the other is characterized by greater transparency and exposure to wind. Continuous measurements of temperature, conductivity, and oxygen in the water column, as well as meteorological conditions (wind, pressure, heat exchanges) have been conducted since October 2021. CO2 fluxes measured using a floating chamber and dissolved gases (CO2, CH4, N2O) at the surface were measured on a daily cycle for 2-week periods in July 2022 and August 2023, with bubble traps quantifying ebullition rates. Diffusive CO2 fluxes are in line with estimates for other thermokarst lakes, ranging from –2 to 17 mmol m–2 d–1 in July 2022 (during a particularly cold period) and from 8 to 66 mmol m–2 d–1 in August 2023, a period of stronger stratification. Turbulence, characterized by the gas transfer coefficient k600, was higher in 2023 (0.4 to 10.4 cm h–1) than in 2022 (1.1 to 4.7 cm h–1). CH4 emission through ebullition was more than 6 times higher than through diffusion in the more humic and sheltered lake (13 ± 5.5 mol m–2 d–1) and almost 7 times higher than in the more transparent and exposed lake (2 ± 1.5 mmol m–2 d–1), where ebullition was of the same order of magnitude than diffusion. Diurnal cycles were characterized by the nocturnal mixing of surface waters with deeper waters enriched in CO2, leading to a peak in CO2 fluxes in the morning, which gradually decreased over the course of the day with the establishment of thermal stratification due to solar radiation, and the potential uptake by primary production. Overall, these results highlight the complex interactions between environmental factors influencing GHG emissions in thermokarst lakes, and the major differences that can exist between adjacent lakes.
Hyper Boris integrators for particle-in-cell simulation
Authors: Zenitani Seiji , Kato Tsunehiko N
Published: March 2024

We propose a family of numerical solvers for the nonrelativistic Newton-Lorentz equation in particle-in-cell (PIC) simulation. The new solvers extend a popular 4-step procedure, which has second-order accuracy in time, in several ways. First, we repeat the 4-step procedure n cycles, using an n-times smaller timestep (Delta_t/n). To speed up the calculation, we derive a polynomial formula for an arbitrary cycling number n, based on our earlier work (Zenitani & Kato 2020, Comput. Phys. Commun.). Second, prior to the 4-step procedure, we apply Boris-type gyrophase corrections to the electromagnetic field. In addition to the magnetic field, we amplify the electric field in an anisotropic manner to achieve higher-order (N=2,4,6... th order) accuracy. Finally, we construct a hybrid solver of the n-cycle solver and the Nth-order solver. We call it the hyper Boris solver. The (n,N) hyper Boris solver gives a numerical error of ~ (Delta_t/n)N at affordable computational cost.
Analysis of the Fertilizer Footprint of Principal Crops in China: A Spatial Allocation Perspective
Authors: Wu Yifan , Liu Jingyu , Geng Yong
Published: March 2024

Utilizing the sophisticated Multi-Regional Input-Output Analysis (MRIO) approach, this investigation meticulously examines the nitrogen (N), phosphorus (P), and potassium (K) fertilizer footprints associated with predominant crops throughout various Chinese provinces. Crucial provinces, namely Heilongjiang, Jiangsu, Shandong, and Henan, manifest a pronounced geographical aggregation in fertilizer footprints. Intriguingly, Heilongjiang, Shandong, and Henan collectively represent 49.2% and 42.7% of the cumulative national footprint.From a provisioning perspective, the assimilation of N, P, and K fertilizers predominantly gravitates towards Heilongjiang, Shandong, Henan, Jiangsu, and Anhui, cumulatively contributing 32.74%, 35.73%, and 36.48% to the nation's aggregate input. Distinctly, regions such as the Yangtze River Delta, Pearl River Delta, and the Beijing-Tianjin-Hebei conurbation emerge as paramount crop consumption hubs, with aggregate consumptions scaling to 4505.12 Gg, 1741.71 Gg, and 2026.57 Gg, respectively. Notably, the exogenous crop provisions in metropolises like Shanghai and Beijing play a pivotal role in shaping their N, P, and K footprints, quantified at 6.78%, 5.56%, and 5.79%, and 1.26%, 1.37%, and 1.71%, respectively.Furthermore, three salient regions—the Northeastern Plains, the Huang-Huai-Hai Plains, and the Middle to Lower tracts of the Yangtze River—collectively encompass 57.4%, 66.1%, and 66.26% of the national N, P, and K footprints. Compellingly, the dynamics of crop footprint migration in provinces such as Henan, Heilongjiang, and Shandong appear to be predominantly modulated by wheat and corn.In summation, this scholarly endeavor elucidates the intricate spatial delineation of the fertilizer footprint, its translocation mechanisms, and its intricate interplay with socio-economic and demographic paradigms, thereby laying a robust theoretical groundwork for augmenting fertilizer efficacy and championing the cause of sustainable agricultural practices.
Impact of the ocean-atmosphere coupling on Mediterranean cyclones
Authors: Chericoni Marco , Fosser Giorgia , Anav Alessandro
Published: March 2024

The Mediterranean basin is well recognized as one of the main climate change hotspots; besides, this region is one of the most active cyclogenetic area of the Northern Hemisphere with a large number of intense cyclones occurring every year. Intense Mediterranean cyclones are often responsible for extreme precipitation and strong wind events leading to severe socio-economic and environmental impacts especially over densely populated coastal areas. Complex feedback between the Mediterranean Sea and the atmosphere on various temporal and spatial scales plays a major role in the variability in and extremes of the regional climate system.This study aims to investigate the impact of the ocean-atmosphere coupling on the regional climate during intense Mediterranean cyclones. To this end, two simulations are performed using the ENEA-REG regional earth system model at 12 km atmospheric horizontal resolution over the Med-CORDEX domain, both driven by ERA5 reanalysis. The first experiment uses the mesoscale WRF model with prescribed ERA5 Sea Surface Temperature (SST), while the second is coupled to the MITgcm ocean model at horizontal resolution of 1/12°. Cyclones are tracked by applying a Lagrangian algorithm to the mean sea level pressure field. The 500 most intense cyclones mainly occur in winter over the Thyrrenian, Adriatic, Ionian and Aegean Sea. They are similarly reproduced between WRFs and ERA5 in terms of seasonal and spatial distribution, due to the same large-scale atmospheric conditions. The coupled simulation is compared with the standalone WRF in terms of sub-daily fields, such as evaporation, precipitation and wind speed, during the mature stage of the cyclones. The different SST distribution between the models appears to be the main controlling factor for the differences in the atmospheric properties affecting not only the surface, but also the entire atmospheric boundary layer (ABL) and its height, due to the mixing of the turbulent processes, enhanced during intense cyclones. A statistically significant higher specific humidity and wind speed are found in the coupled model from the surface to the top of the ABL, as well as higher precipitation over sea and coastal areas. These results are consequences of higher turbulent heat and moisture fluxes in the coupled model that destabilize the ABL and provide higher moisture content available for convection.We conclude that the use of the coupled model is crucial for a more realistic representation of the energy redistribution in both the ocean mixed layer and the ABL during intense Mediterranean cyclones. This highlights the importance of the coupled model to study the influence of climate change on intense Mediterranean cyclones and associated impacts under different future scenarios.
Rhizodeposition in the Plant Economic Space for 15 grassland species and its links to biogeochemical cycles (C,N)
Authors: Folacher Chloé , Forey Estelle , Branger Angèle , Chauvat Matthieu , Henneron Ludovic
Published: March 2024

Understanding how photosynthetic carbon is delivered into the soil system through rhizodeposition is of utmost importance in a changing world, as it represents an essential part of carbon cycling in soils. The plant economic space (PES) is a theoretical model representing plant strategies resource acquisition strategies based on two independent trade-offs: (i) resource acquisition vs conservation and (ii) exploration outsourcing (cooperation with mycorrhizal fungi) vs do-it-yourself. The PES is known to be related to a set of chemical and morphological traits, but some physiological traits such as rhizodeposition lack attention because they are harder to measure, while they are crucial for our understanding of resource allocation strategies and their linkages to ecosystem processes. For example, gross rhizodeposition can represent more than 40% of belowground carbon allocation.We aimed to provide more insights on the relationship between rhizodeposition and the two dimensions of the PES, with a focus on the second axis, as arbuscular mycorrhizal fungi (AMF) are supposed to play an essential role of sink in the sink/source model of rhizodeposition. To do so, we grew 15 grassland plant species with contrasting resource acquisition strategies in a 3-month long pot experiment, with or without litter inputs. By means of 13C pulse-labelling, we traced carbon fluxes from recent photosynthates in major pools, including above-and belowground parts of the plant, but also in microbial biomass and microbial functional groups using PLFAs, soil organic matter, and soil respiration. We also measured net and gross nitrogen mineralisation.We hypothesise that (i) rhizodeposition will be strongly link to the fast-slow gradient, fast-growing species being associated with higher rhizodeposition rates, but (ii) rhizodeposition will also show significant relationships with the exploration gradient, as tighter plant-soil biota association – including more AMF colonisation – could promote higher rhizodeposition rate, because of sink mechanisms. Higher rhizodeposition should also be associated (iii) with a shift in microbial community toward functional groups more dependant to plant carbon such as AMF and Gram negative bacteria, as well as (iv) higher soil respiration and nitrogen mineralisation.
Field and numerical experiments of subsurface drainage systems in saline and clay interlayered fields in arid regions
Authors: Guo Chenyao , Yao Chenzhi , Wu Jingwei , Qin Shuai , Yang Haoyu
Published: March 2024

A reasonable layout of subsurface drainage systems is considered essential for maximizing its drainage and salt control effectiveness. In the saline-alkali farmland of arid regions in Northwest China, clay interlayers are common; however, the influence of clay interlayers on the layout of the subsurface drainage has not been extensively considered in the literature. This study investigated the process of subsurface drainage and salt discharge in salt-affected fields with clay layers using field experiments and numerical simulations. Four field experiments were conducted, considering three different relative positions between the drainage pipes and clay interlayers. The results showed that the clay interlayers hindered water infiltration; however, the distribution of soil salinity in the soil profile varied with the buried depth of drainage pipes at different positions relative to the clay layer. When the buried depth of drainage pipes increased, the amount of water and salt discharged from drainage pipes increased, and the increase rate in salt discharge was greater than water drainage. A numerical model was calibrated and validated using the field experiment data, and 25 orthogonal numerical experiments were conducted to investigate the soil desalination effects of buried depth of drainage pipes, spacing between the pipes, permeability of the interlayer, and position of the clay interlayer. The results showed that the drainage pipe buried depth, spacing, and permeability of the clay layer had significant effects on the desalination rate (P < 0.01), while the position of the clay interlayer had no significant effect (P > 0.05). Therefore, subsurface drainage pipes should be placed below the clay interlayer. The desalination rate linearly increased with the buried depth of drainage pipe and permeability of the interlayer, and it increased exponentially with decreased spacing. An empirical formula for soil desalination rate considering interlayer and subsurface drainage pipe layout parameters was fabricated and used to determine the appropriate layout parameters.
A Matter of Geometry: Predicting Single Fracture Permeability by Evaluating Imaging Methods and Persistent Homology Analysis  
Authors: Fuchs Marco , Suzuki Anna , Hasumi Togo , Hale Sina , Blesch Larissa , Menberg Kathrin , Rau Gabriel C. , Blum Philipp
Published: March 2024

Fractures play a significant role in various geoscientific applications, such as nuclear waste disposal, geothermal energy, and hydrocarbon extraction. Understanding the governing hydraulic characteristics of fractures and their impact on flow processes is crucial for the success of these applications. Among the many parameters that affect fracture behavior, permeability stands out as one of the most critical. Several methods have been developed to investigate fracture permeability, including flow-through experiments and numerical hydraulic simulations. However, it is important to note that the geometry of a fracture greatly influences its permeability. This study focuses on examining different workflows to directly estimate the permeability of a single fracture based on its geometry. In the first step to achieve this, we apply and evaluate three fracture surface imaging methods: (1) handheld laser scanner (HLS), (2) mounted laser scanner (MLS), and (3) Structure from Motion (SfM). We conducted our study using a bedding joint in Flechtinger sandstone as the fracture sample. After capturing the fracture geometries using these imaging methods, we perform numerical flow simulations to estimate hydraulic apertures. Our findings reveal that due to limited resolution and accuracy, the HLS is not suitable for use in numerical flow simulations. However, MLS and SfM result in hydraulic apertures that exceed experimental air permeameter measurements (81 ± 1 µm). The hydraulic apertures obtained using MLS and SfM are 163 µm and 207 µm, respectively. To bridge the discrepancy between simulations and measurements, we stepwise increase the contact area, resulting in hydraulic apertures of 85 µm at 5 % contact area and 83 µm at 7 % contact area for MLS and SfM, respectively. In the second step, we utilize the topological persistent homology (PH) method to calculate permeability directly from the fracture geometry derived from MLS, eliminating the need for laboratory experiments or numerical simulations. We create three different datasets of the same fracture, varying in spatial resolution (200 µm, 100 µm, and 50 µm). The results from the PH analysis demonstrate hydraulic apertures ranging from 73 µm to 92 µm, which align closely with the air permeameter measurements. Notably, the accuracy of fracture permeability prediction improves with higher resolution. In summary, this study presents an effective workflow that enables the direct estimation of fracture permeability based on the geometry of a sandstone fracture. By utilizing different imaging methods and topological analysis, we provide valuable insights into understanding and predicting fracture permeability.
Spatially explicit assessment of heat health risk in the Yangtze River Delta, China using multi-source remote sensing and socio-economic data
Authors: Wu Hanyi , Pan Yaozhong , Zhao Chuanwu , Zhu Yu
Published: March 2024

With frequent extreme heat events (EHEs), rapid urbanization, and uneven social development, the impact of EHEs on health has attracted increasing attention. Comprehensive assessment of heat-related health risks is important for tolerating hot weather. To address the limitations of previous assessment methods in regard to the appropriateness of indicators and the fineness of mapping scales, in this paper, we proposed a quantitative method for assessing heat-related health risks at the grid scale. A combination of multisource remote sensing data and demographic-socioeconomic data was utilized to develop an integrated heat health risk index (HRI) that considers the three dimensions of heat hazards, human exposure, and vulnerability in the Yangtze River Delta (YRD). Compensating for the limitations of land surface temperature (LST) and meteorological station data, daily maximum and minimum air temperatures were retrieved to characterize heat hazards and subsequently calculate the hazard index. Gridded population density data were also developed based on nighttime light data to calculate the exposure index. Multidimensional indicators were derived to describe vulnerability, including demographic characteristics, socioeconomic conditions, infrastructure status, governance, and medical resources. By combining the hazard, exposure, and vulnerability indices, an HRI map of the YRD was developed. Furthermore, the spatial heterogeneity and the dominant factors of the heat health risk were examined. The high-risk areas were predominantly concentrated in southern Jiangsu, the Shanghai-Hangzhou Bay urban agglomeration, and the central urban area of prefecture-level cities. This phenomenon suggests synergy between increased human exposure and heat hazards in these metropolitan areas. Due to a low economic development level, the resilience against heat risks in underdeveloped regions such as northern Anhui is low. This study contributes to the identification of areas vulnerable to heat stress, which can help decision-makers optimize local urban heat risk management strategies.
Examining Daily Snow Depths at the Catchment Scale in Canada Using CMIP
Authors: Abdelmoaty Hebatallah , Papalexiou Simon , Gaur Abhishek , Markonis Yannis
Published: March 2024

The lack of reliable data on daily snow depth (SD) is a significant challenge for studying water systems, ecology, and resources. Climate models present a potential solution for generating daily SD data, but the literature has not thoroughly explored how accurately they simulate this data. This study investigates the capabilities of CMIP6 climate models to replicate daily SD characteristics in eleven major Canadian catchments. The results depict that CMIP6 simulations overestimate the average SD values by a median of 57.7% (6.9 cm). In the Arctic and Pacific regions, this overestimation becomes particularly pronounced. However, the simulations align more closely with observations in smaller catchments with homogenous land characteristics. This finding suggests a shortcoming in how these models simulate different land types within the grid. Additionally, the models appear to overestimate the snow cover duration, with a median underestimation of 30.5 days. This overestimation could be due to the models failing to accurately account for the rates at which snow accumulates and melts away. However, the models perform relatively well when predicting extreme SD conditions. This study carries valuable implications for refining the outputs of climate models and effectively utilizing them in impact studies.
Exploring the feasibility of uni-directional ATES in high ambient groundwater flow aquifers
Authors: Silvestri Valerio , Bloemendal Martin , Crosta Giovanni , Previati Alberto
Published: March 2024

In the context where the member states of the European Union are asked to reach the goal of net zero emission of greenhouse gases before 2050, many cities all over Europe are adopting sustainable energy systems. One of the primary sources of CO2 emission are building heating and cooling systems. As aquifers are commonly present in many urban areas, ground coupled heat pumps are a renewable solution that many countries are adopting to replace fossil based heating and cooling techniques.Aquifer thermal energy storage (ATES) is attained by storing thermal energy in groundwater aquifers. Hence, a key aquifer characteristic for ATES is the natural groundwater flow velocity. For velocities less than 25 m/y, bi-directional ATES is usually possible. For groundwater flow velocities greater than 25 m/y, ATES is still possible, but requires multiple doublets with a specific well placement to be able to compensate for the groundwater flow via upstream injection and downstream extraction. Alternatively, “pump and dump” systems, which generate thermal plumes that affect the downstream groundwater temperature and are not desirable for other users, are adopted.A possible way to tackle the issue of aquifers with high ambient groundwater flow velocity is to combine the two solutions described above by applying a uni-directional pumping scheme allowing to compensate for the groundwater flow by constantly injecting in the upstream well and extracting from the downstream well. Spacing of the wells should be adjusted to the storage cycle length and natural groundwater flow velocity to ensure re-capture the energy injected within the aquifer in the previous season from the upstream well and transported to the down-gradient extraction well by the groundwater flow. This concept would also mitigate the downstream effect of a thermal plume. In this research the results of a sensitivity and feasibility analysis of this concept are presented. The results show that optimal inter-well distance not only depends on storage cycle length and groundwater flow velocity, but also on storage volume. Downstream thermal pollution can be avoided and recovery of the heat/cold stored can reach values between 50-60% depending on the conditions.
Investigation of Physical Processes in Development of Hydrostatic Imbalance
Authors: Sun Jielun , Wulfmeyer Volker , Spaeth Florian , Voemel Holger , Brown William , Oncley Steven
Published: March 2024

The hydrostatic equilibrium addresses the approximate balance between the positive force of the vertical pressure gradient and the negative gravity force and has been widely assumed for atmospheric applications. The hydrostatic imbalance of the mean atmospheric state for the acceleration of vertical motions  in the vertical momentum balance is investigated using tower, the Global Positioning System radiosonde, and Doppler Lidar and Radar observations throughout the diurnally varying atmospheric boundary layer (ABL) under clear sky conditions. The imbalance is found to be mainly due to the vertical turbulent transport of changing air density as a result of thermal expansion/contraction in response to air temperature changes following surface temperature changes. In contrast, any pressure change associated with air temperature changes is small, and the positive vertical-pressure-gradient force is strongly influenced by its background value. The imbalance is found to be mainly responsible for the vertical advection of vertical turbulent motions, which is the vertical variation of the turbulent velocity variance. The vertical variation of the turbulent velocity variance from its vertical increase in the lower convective boundary layer (CBL) to its vertical decrease in the upper CBL is observed to be associated with the sign change of the imbalance from positive to negative due to the vertical decrease of the positive vertical-pressure-gradient force and the relative increase of the negative gravity force as a result of the decreasing upward transport of the low-density air. The imbalance is reduced significantly at night but does not steadily approaches to zero. Understanding the development of hydrostatic imbalance has important implications for understanding large-scale atmosphere especially for cloud development. 
Spatial Regression Modeling and Distribution of Submarine Landslides in the Negros–Sulu Trench System
Authors: Nawanao Lyndon , Ramos Noelynna
Published: March 2024

Large submarine landslides are a global concern as they can trigger tsunamis with no clear precursors. While geological characterization of submarine landslides remains a challenge to many areas worldwide, the availability of global bathymetric datasets and spatial analysis tools has led to progress in mapping these submarine geomorphological features. Morphological and statistical analyses of submarine landslides and their attributes enable the identification of regions susceptible to large submarine failures and covariates that are good predictors of submarine landslide volume. This study identifies significant clusters of large submarine landslides mapped (n=1214) in the Negros–Sulu Trench System by testing the spatial dependence of volume using global Moran’s I and Getis-Ord (Gi*) statistic. This study further explores a spatial model that best elucidates the distribution of submarine landslide volume. Global Moran’s I suggests significant positive spatial autocorrelation, while Gi* statistic reveals local clustering of large-volume submarine landslides, where the densest clustering occurs offshore of southern Panay Island. Among the 18 spatial regression models, the (1) univariate spatial Durbin, (2) nested, and (3) spatial Durbin error with the maximum slope as the predictor have the lowest Akaike information criterion (AIC) of 2056.1, 2057.0, and 2057.8, respectively. The spatial regression models also revealed that mean depth is a poor predictor of submarine landslide volume. Log likelihood-ratio test suggests a simpler option of the nested model. The spatial Durbin error model better represents the underlying local heterogeneities such as sediment flux and subduction processes in triggering submarine landslides than the global spillover effects of the spatial Durbin model. Furthermore, this study highlights the dominant role of slope and tectonic processes that induce oversteepening, triggering large submarine landslides that may induce damaging tsunamis. The identified offshore areas with significant clustering of large submarine landslides are valuable information for offshore geophysical surveys and tsunami hazard assessment in the region.
A Temporal Study of the Proglacial Lakes Surrounding Múlajökull Outlet Glacier, Iceland Between 1987 and 2021.
Authors: Lee Natasha , Shepherd Andrew , Hill Emily , Carr Rachel
Published: March 2024

Proglacial lakes often form due to the availability of meltwater at a glacier margin. The greatest increase in proglacial lake area and volume is currently occurring in the Arctic. This research quantified the annual change and seasonal variations in proglacial lake area and colour of Múlajökull outlet glacier southeast Hofsjökull. The Normalised Difference Water Index is used to calculate the annual and seasonal area of proglacial lakes between 1987 and 2021 in Google Earth Engine. As the terminus of Múlajökull has retreated, the number and area of proglacial lakes has increased. This has been most noticeable after the year 2000 following which, the glacier terminus retreated up to 400m. Results from this study have shown a retreat of Múlajökull terminus caused increase in area of proglacial lakes. Between 1987 and 2021 an increase in proglacial lake area from 0.16 km2 to 1.27 km2 was observed and the glacier terminus retreated by 700m. In addition to this, spatial and temporal variation of proglacial colour was observed between 1987 and 2021. The results of this study will provide greater insight into the annual and seasonal changes in the proglacial lake area and colour of Múlajökull outlet glacier.
An innovative soil mesocosm system for studying the effect of soil moisture and background NO contribution on soil surface trace gas fluxes 
Authors: Subramaniam Logapragasan , Engelsberger Florian , Wolf Benjamin , Dannenmann Michael , Butterbach-bahl Klaus
Published: March 2024

This research investigates the complex dynamics of how soil NO concentrations and soil moisture affect the exchange of greenhouse gases between soils and the atmosphere. To this end, we have developed and tested an automated soil mesocosm system (AU-MES), which allows for dynamically change of headspace and soil NO concentrations, measures trace and greenhouse gas fluxes based on a dynamic chamber approach, and observes and manipulates key soil and environmental metrics such as temperature, light conditions, or moisture.Initial a brief phase of soil-only incubation experiments demonstrated the influence of soil moisture and soil and headspace NO concentrations of 400 ppbv on gas emissions. We observed that under low soil moisture conditions (30% water-filled pore space), nitrification was favored, as indicated by increased emissions of NO (at zero NO concentration 0.191 kg N ha-1 and at high NO concentration 0.180 kg N ha-1) and NO2 (at zero NO concentration 0.002 kg N ha-1 and at high NO concentration 0.001 kg N ha-1). In contrast, under higher soil moisture conditions (50% water-filled pore space), we observed increased N2O (at zero NO concentration 0.149 kg N ha-1and at high NO concentration 0.147 kg N ha-1) and CO2 (at zero NO concentration 0.122 t C ha-1 and at high NO concentration 0.110 t C ha-1)fluxes, suggesting that denitrification may become more important. These results, particularly under soil rewetting and fertilizer application, illustrate the complex interplay between soil nitric oxide concentrations, moisture levels, microbial activities, and gas emissions.In summary, the AU-MES system is a valuable tool for investigating soil-atmosphere gas interactions and the effects of various environmental elements on these processes. Our research provides important insights into how nitric oxide may affect soil processes and trace gas exchange at the soil-atmosphere interface.Keywords Automated soil mesocosm system, nitric oxide, gas concentrations, headspace purging, soil purging