bluuebunny/crossref_metadata_2025 huggingface dataset:
Vertical distribution of radioactive cesium-rich microparticles in forest soil of Hamadori area, Fukushima Prefecture
Authors: Tatsuno Takahiro , Waki Hiromichi , Nihei Naoto , Ohte Nobuhito
Published: February 2023

A lot of radionuclides were scattered after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident. Previous studies showed that there were FDNPP-derived radioactive cesium-rich microparticles (CsMPs) with the size of a few μm in the soil and river water around Fukushima Prefecture[1]. CsMPs have high radioactive cesium (Cs) concentration per unit mass, therefore they can be one of the factor in overestimating the Cs concentration in samples. Because Cs in CsMPs may not react directly with clay particles unlike the Cs ion in liquid phase, it is considered that CsMPs work as Cs carrier in soils[2]. However, unlike ionic Cs and Cs adsorbed onto clay particles, the distribution and dynamics of CsMPs in soils have not been clarified. In this study, we investigated vertical distribution of CsMPs in the forest soil and the soil properties in Fukushima Prefecture, Japan.Soil samples were collected from the forest in the difficult-to-return zone, approximately 10 km away from the FDNPP. The undisturbed soil samples were collected from 0-35 cm soil depth at 5 cm intervals using core sampler to investigate soil properties. Furthermore, litter samples on the surface soil layer were collected. Using these samples, the vertical distribution of Cs concentration in the soil and Cs derived from CsMPs were investigated. Cs concentration in samples placed in 100 mL of U8 container was measured using a germanium semiconductor detector. Cs derived from CsMPs was evaluated using an Imaging plate with reference to the method ffor quantification of CsMPs[3].Like Cs adsorbed on the soil, CsMPs were also mostly distributed in the soil surface layer between o and 5 cm of soil depth. We considered that straining may be one of the mechanism of CsMPs retention on the soil surface. Bradford et al. (2006) [4] showed that straining might be a significant mechanism for colloid retention when the average particle size in the porous medium is less than 200 times larger than the colloidal particle size. In this study, assuming the CsMPs size of approximately 1 µm, the average particle size of the soil collected from surface layer 0-5 cm was less than 200 times that of CsMPs. However, the average particle size decreased in deeper layer than 5 cm, therefore, it was considered that straining mechanism could be stronger.This work was supported by FY2022 Sumitomo Foundation and FY2022 Internal Project of　Institute of Environmental Radioactivity, Fukushima University. References[1]　Igarashi, Y. et al., 2019. J. Environ. Radioact. 205–206, 101–118.[2]  Tatsuno, T et al., 2022. J. Environ. Manage. 329, 116983.[3]　Ikehara et al., 2018. Environ. Sci. Technol. 52, 6390–6398.[4]　Bradford et al., 2003. Environ. Sci. Technol. 37, 2242–2250.
Global warming accelerates soil heterotrophic respiration
Authors: Nissan Alon , Alcolombri Uria , Peleg Nadav , Galili Nir , Jimenez-Martinez Joaquin , Molnar Peter , Holzner Markus
Published: February 2023

Carbon efflux from soils is the largest terrestrial carbon source to the atmosphere, yet it remains one of the most uncertain fluxes in the Earth’s carbon budget. A dominant component of this flux is heterotrophic respiration, influenced by several environmental factors, most notably soil temperature and moisture. We developed a mechanistic model from micro to global scale to explore how changes in soil water content and temperature affect soil heterotrophic respiration. Simulations, laboratory measurements, and field observations validate the new approach. Estimates from the model show that heterotrophic respiration has been increasing since the 1980s at a rate of about 1.7% per decade globally. Using future projections of surface temperature and soil moisture, the model predicts a global increase of about 40% in heterotrophic respiration by the end of the century under the worst-case emission scenario, which is driven principally by the reduction of soil moisture rather than temperature increase.
Dynamics and characteristics of monsoonal orographic rainfall variability over Eastern Himalaya
Authors: Kad Pratik , Ha Kyung-Ja
Published: February 2023

The Himalayas are an essential driver of the monsoon and climate system. However, river flooding during the monsoon impacts the most densely populated region of Himalayan downstream regions annually. Previous studies also reported elevation-dependent warming, rainfall changes, ice-sheet melting, and extremes in the Himalayas. Nevertheless, due to complicated orography, Himalayan precipitation dynamics remain quantitatively limited on a spatial scale compared to other monsoon regions. In the context of climate change, recent studies show how melting glaciers and snow, along with monsoonal rains causing recurrent floods, play a role. This study examined the last 43 years (1979-2021) to emphasize the interannual variability. We found a robust signal over in the Eastern Himalayas, where the orographic features and process plays a dominant role. Further analysis indicates Monsoonal rainfall is the main factor, rather than melting snow for these unusually extreme years. Regional monsoonal circulation connected to Walker circulation controls the variability of Himalayan monsoonal rainfall via circulation linkages. Our findings illustrate the wet and dry response mechanisms in the eastern Himalayas. The conclusions are drawn from this work highlight the role of natural variability, which might help understand Himalayan floods and their predictability. Keywords – Himalayas, Interannual variability, Monsoon dynamics, Orographic features, River floods
On the impact of bio-geomorphological gradients on soil organic carbon storage in tidal wetlands
Authors: Schwarz Christian , van Mieghem Erwin , Laukens Maxime
Published: February 2023

Climate change is one of the most challenging problems facing society today. Evaluating effects of global warming from rising atmospheric carbon dioxide (CO2) concentrations requires resolving the processes that drive Earth’s carbon stocks and flows. Although biogeomorphic wetlands (peatlands, mangroves, salt marshes, and seagrass meadows) cover only 1% of Earth’s surface, they store 20% of the global organic ecosystem carbon. Carbon budgets and carbon storage rates in coastal wetlands, and more specifically temperate salt marshes, are assessed by ignoring bio-geomorphic gradients and vegetation distribution. Generic estimations of carbon across the wetland leads to major inaccuracies in, estimated carbon stocks, and unclear predictions in how climate change might alter biogeomorphic feedbacks (i.e. reciprocal organism-landform interactions) that can switch these ecosystems from carbon sinks into sources. This study focuses on disentangling the impact of bio-geomorphological gradients, on distribution of sediments, plant species composition and soil organic carbon (SOC). We carried out stratified field surveys on sediment characteristics (e.g., soil organic matter content and grainsize distribution) and compared results to a remote sensing analysis on plant species distributions and drainage pathways of water and sediment. Results indicate that soil organic carbon content follows distinct spatial patterns arising from bio-geomorphic interactions between allochthonous suspended particle transport and autochthonous production. These relationships can be used to improve estimates of carbon stocks in tidal wetlands and spatial upscaling.
Landslide impacts on sediment dynamics in mountainous rivers after large earthquake and typhoon events: A sediment connectivity approach
Authors: Lin Ying-Tong , Turnbull Laura , Wainwright John
Published: February 2023

Small mountainous rivers (SMRs) produce about 40% of the world’s sediment discharge from land to ocean. The dominant sources of this sediment are earthquake and typhoon-driven landslides. It is widely accepted that earthquake-induced landslides tend to locate at hillslopes, while typhoon-induced landslides tend to cluster at hillslope toe areas. These differences in landslide drivers and landslide location together determine the connectivity of resulting sediment transfers from the source (landslides) to the river network. Therefore, understanding when and where earthquake and typhoon-driven landslides occur, and the pathways and timescales over which these sediment sources are connected to river channels can help us determine the relative controls of earthquakes and typhoons on sediment discharge in SMRs. Here, we illustrate how detailed spatial and temporal mapping of landslides, using Landsat imagery within Google Earth Engine, enables us to better understand sediment connectivity in SMRs, and improve our understanding of the controls on sediment discharge in SMRs. We focus our analysis on the period between 1999 and 2020, which includes the 1999 Chi-Chi earthquake (Mw=7.7) and typhoon Morakot, which generated over 3000 mm of rainfall between 5th and 10th August 2009. The results show that we can identify event-induced landslide areas at a higher temporal resolution than the open-source landslide dataset from the Forest Bureau, Taiwan, which enables us to refine our understanding of the relative controls of discrete events (i.e. earthquakes and typhoons) on landslides and connected sediment transport pathways, and determine the timescales over which they lead to elevated sediment discharge in SMRs. Refining our understanding of earthquake and typhoon-driven controls on landslides in SMR catchments and cascading impacts on sediment export from SMRs is particularly important given the recent intensification of rainfall intensities that are anticipated to continue in the future.
Differential response of plant transpiration to uptakeof rainwater-recharged soil water for dominanttree species in the semiarid Loess Plateau
Authors: Tang Yakun
Published: February 2023

Whether uptake of rainwater-recharged soil water (RRS) can increase plant transpiration in response to rainfall pulses requires investigation to evaluate plant adaptability, especially in water limited regions where rainwater is the only replenishable soil water source. In this study, the water sources from RRS and three soil layers, predawn (Ψpd), midday (Ψm) and gradient (Ψpd−Ψm) of leaf water potential, and plant transpiration in response to rainfall pulses were analyzed for two dominant tree species, Hippophae rhamnoides subsp. sinensis and Populus tomentosa, in pure and mixed plantations during the growing period (June–September). Mixed afforestation significantly enhanced Ψpd − Ψm, RRS uptake proportion (RUP), relative response of daily normalized sap flow (SFR), and reduced the water source proportion from the deep soil layer (100–200 cm) for both species (P < 0.05). In pure and mixed plantations, the large Ψpd − Ψm was consistent with high SFR for H. rhamnoides, and the small Ψpd − Ψm was consistent with low SFR for P. tomentosa, in response to rainfall pulses. Therefore, H. rhamnoides and P. tomentosa exhibited anisohydric and isohydric behavior, respectively, and the former plant species was more sensitive to rainfall pulses than P. tomentosa. Furthermore, in pure plantations, the SFR was significantly affected by RUP and Ψpd − Ψm for H. rhamnoides, and was significantly influenced by Ψpd − Ψm for P. tomentosa (P < 0.05). However, the SFR was significantly influenced by RUP and Ψpd − Ψmfor both species in the mixed plantation. These results indicate that mixed afforestation enhanced the influence of RRS uptake to plant transpiration for these different rainfall pulse sensitive plants. This study provides insights into suitable plantation species selection and management considering the link between RRS uptake and plant transpiration in water limited regions.
The Fresnel Platform for Greater Paris: enhancing the urban resilience with the fully distributed and physically based model, Multi-Hydro
Authors: Drouen Guillaume , Schertzer Daniel , Gires Auguste , Tchiguirinskaia Ioulia
Published: February 2023

The aim of the Fresnel platform of École des Ponts ParisTech is to develop research and innovation on multiscale urban resilience. To achieve this goal, it is therefore conceived as a SaaS (Software as a Service) platform, providing data over a wide range of space-time scales and appropriate softwares to analyse and simulate them over this range.To study the different technical solutions of the water cycle in an urban environment at different scales, RadX now provides a user-friendly graphical user interface to run simulation using a fully distributed and physically based model: Multi-Hydro.This model that has been developed at École des Ponts ParisTech, from four open-source software applications already used separately by the scientific community. Its modular structure includes a surface flow module, sewer flow module, a ground flow module and a precipitation module. It is able to simulate the quantity of runoff and the quantity of rainwater infiltrated into unsaturated soil layers from any temporally-spatially varied rainfall event at any point of the peri-urban watersheds. The spatial and temporal variation of meteorological, hydrological, geological and hydrogeological data across the model area is described in gridded form of the input as well as the output from the model.The use of RadX as a graphical user interface gives users the ability to easily customize the input data for their simulation. They can, for instance, modify the land use to study the effect of urban climate mitigation strategies like green roofs. They can select real hydrological events measured by the ENPC X-Band radar as rainfall input, but also generate virtual rainfall events. To ease the interpretation of the simulation, RadX can render interactive 2D and 3D graphics directly in the users' web browser by the use of open source libraries that focus on performance using low level graphic API. For example, it gives the user an intuitive and efficient way to spot singular points of the infiltration output display. Users can also download the file outputs to use in their GIS software.Other components can be integrated to RadX to satisfy the particular needs with the help of visual tools and forecasting systems, eventually from third parties. Developments are still in progress, with a constant loop of requests and feedback from the scientific and professional world.
Hydrothermal circulation in oceanic crust along Middle America Trench: insights from numerical modeling
Authors: Manea Marina , Sewell Granville , Manea Vlad , Petrescu Lucian
Published: February 2023

Variation of subduction parameters (i.e., plate age and velocity) along trenches show in general a smooth spatial variation. However, despite these gradual changes heat flow measurements show large variations. For example, previous studies show that heat flow direct observations along the Middle America Trench (MAT) range from 14 to 261 mW/m2, without a clear pattern. One of the common hypotheses that can explain such variations is the presence of hydrothermal circulation within the oceanic crust that enters subduction. Here we present modeling results of hydrothermal circulation using finite elements to calculate the flow, temperature and pressure distribution in oceanic crust. We employ PDE2D (www.pde2d.com), a general-purpose finite element program for solving multidimensional partial differential equations, to solve the coupled equations of continuity, Darcy equation, and energy conservation equation in two dimensions. Our model setup incorporates a low permeability sedimentary layer, a high permeability oceanic crust layer and a basal heat source. Modeling results show that hydrothermal circulation is sensitive to the basal source and multiple convection cells are formed within the permeable oceanic basaltic crust. The sedimentary layer located on top of the permeable layer acts as an insulator. Therefore, smooth temperature fluctuations are observed at the surface. We adapted this model setup and incorporate a series of permeable paths in the sedimentary layer that connect the oceanic crust with the ocean bottom. Modeling results show significant changes in the convection patterns for the oceanic crust, and depending on the width of the permeable conduits and basal heat source, high temperature water plume can infiltrate all the way to the ocean bottom. Some models show that these high temperature plumes have a transitory character and they are followed by infiltration of cold seawater into the oceanic aquifer. Our modeling results show that the observed large heat flow variations along oceanic trenches can be attributed to hydrothermal circulation only when permeable pathways connect the permeable upper crust with the ocean.
Probabilistic analysis of river levees under consideration of time-dependent loads
Authors: Öttl Marco Albert , Bender Jens , Stamm Jürgen
Published: February 2023

In the analysis regarding the stability of river dikes, the interactions between the load magnitude of the flood level and the resulting percolation are found to be a highly relevant process. After all, the seepage line separates the cross-sectional area into the water-saturated and the unsaturated crosssectional parts. For homogeneous levees, the position of the seepage line in the stationary case is imprinted in the system by the outer cubature and is well on the safe side for real flood events. In the non-stationary case, the position of the seepage line depends primarily on the changing water level of a flood hydrograph, the resulting water content and suction stresses in the dike, as well as the saturated permeability of the dike construction materials. In the current dimensioning practice according to DIN 19712 and the German DWA-M-507, the characteristic of the hydrograph is not directly applied. So far, for example, the resulting damming duration of a flood hydrograph is only considered indirectly.This paper presents a methodology, which quantifies natural dependency structures for a selected dike section by synthetically generated dimensioning hydrographs in a probabilistic design. These results are then integrated directly into the geohydraulic process of water penetration. Based on selected water level and discharge time series at a dike section, flood waves can be described in five parameters using the extended flood characteristic simulation according to MUNLV1. After successfully adapting suitable distribution functions, dependencies in the load structure are quantified in the next step using Copula function. Subsequently, any number of synthetic flood hydrographs can be generated by combining these parameters. In keeping with the principle of the Monte Carlo simulation, a sufficiently high number of synthetic events results in extreme conditions with a low probability of occurrence being reliably represented.Using a developed routine, the process of moisture penetration for the individual flood hydrographs can be simulated and visualized in a transient, geohydraulically numerical model at different points in times. Finally, statements regarding the behavior patterns of the resulting seepage lines, based on the loading situation can be derived and predicted. Based on these results, a reliability analysis then shows the stability of the dike section under the given extreme conditions.1Ministerium für Umwelt, Landwirtschaft, Natur und Verbraucherschutz des Landes Nordrhein-Westfalen
Airborne observations of riming in arctic mixed-phase clouds during HALO-(AC)3
Authors: Maherndl Nina , Maahn Maximilian , Moser Manuel , Lucke Johannes , Mech Mario , Risse Nils
Published: February 2023

Ice crystal formation and growth processes in mixed-phase clouds (MPCs) are not sufficiently understood leading to uncertainties of atmospheric models in representing MPCs. One of these processes is riming, which occurs when liquid water droplets freeze onto ice crystals. Riming plays a key role in precipitation formation in MPCs by efficiently converting liquid cloud water into ice. However, riming is challenging to observe directly and there are only few studies quantifying riming in Arctic MPCs.In this study, we derive the normalized rime mass 𝑀 to quantify riming. We use airborne data collected during the (AC)3  field campaign HALO-(AC)3  performed in 2022. For this campaign, two aircraft were flying in formation collecting closely spatially collocated and almost simultaneous in situ and remote sensing observations. We aim to quantify 𝑀 by two methods. First, we present an Optimal Estimation algorithm to retrieve 𝑀 from measured radar reflectivities. We find 𝑀 by matching measured with simulated radar reflectivities 𝑍𝑒obtained from in situ particle number concentration observations. As forward operators, we use the Passive and Active Microwave radiative TRAnsfer tool (PAMTRA) and empirical relationships of 𝑀 and particle properties. The latter are derived via aggregation and riming model calculations. Second, we derive 𝑀 from in situ measured particle shape. We calculate the complexity 𝜒 of in situ measured particles, which relates particle perimeter to area. We then derive 𝑀 from empirical relationships that were again obtained from synthetic particles. We compare the obtained 𝑀 derived by both methods and evaluate the occurrence of riming in terms of meteorological conditions and macrophysical cloud properties to understand external drivers and variability of riming. This will lead to a better understanding of riming and thereby helps to improve modelling of this important arctic MPC process.
Towards machine-learning calibration of cloud parameters in the kilometre-resolution ICON atmosphere model
Authors: Eichholz Hannah Marie , Kretzschmar Jan , Watson-Parris Duncan , Umlauft Josefine , Quaas Johannes
Published: February 2023

In the preparation of the global kilometre-resolution coupled ICON climate model, it is necessary to calibrate cloud microphysical parameters. Here we explore the avenue towards optimally calibrating such parameters using machine learning. The emulator developed by Watson-Parris et al. (2021) is employed in combination with a perturbed-parameter ensemble of limited-area atmosphere-only ICON simulations for the North Atlantic ocean. In a first step, the autoconversion scaling parameter is calibrated, using satellite-retrieved top-of-atmosphere and bottom-of-atmosphere radiation fluxes. For this purpose, limited area simulations of the north atlantic are performed with ICON. In which different cloud microphysical parameters are changed, in order to evaluate possible influences on the output of radiation fluxes.
Impact of the Long-Term Drainage on the Eddy-Covariance Fluxes in Northern High Latitude Permafrost Regions
Authors: Bolek Abdullah , Schlutow Mark , El-Madany Tarek , Kolle Olaf , Heimann Martin , Goeckede Mathias
Published: February 2023

In the context of global climate change, permafrost thaw in northern high-latitude territories is becoming a major concern due to the vast amount of organic carbon that is stored within this region. To accurately predict the feedback between Arctic permafrost carbon pools and future climate change, detailed insight into current carbon cycle processes and their environmental controls is imperative. A highly valuable data source for this purpose are continuous observations of turbulent exchange fluxes of carbon (e.g. CO2 and CH4 fluxes) and energy (e.g. fluxes of sensible and latent heat) with the eddy-covariance technique, in combination with the monitoring of environmental parameters such as e.g. air or soil temperature and moisture, radiation,  atmospheric turbulence, water table levels, precipitation, and snow depth.In this study, we evaluate the effect of drainage on vertical carbon fluxes and environmental parameters within a Northeast Siberian wet tundra permafrost ecosystem. Our experiment includes two co-located eddy-covariance sites, one reflecting disturbed conditions affected by a drainage system which was built in 2004, and the other as an undisturbed control site. Both towers were identically outfitted with eddy covariance instruments mounted on 5 m tall towers on the floodplain of the Kolyma River near Chersky (68.75 º N, 161.33º E) in Northeast Siberia, Russia. The dataset analyzed here covers the period from July 2013 to December 2021, including continuous coverage throughout the winter seasons. We present a statistical analysis of the long-term trends in the environmental parameters and surface-atmosphere exchange fluxes at both sites. In addition, we relate the carbon and heat fluxes at both sites in the spectral and temporal domain to the inter-annual variability in climate conditions, which include extremes in both summer (temperature, precipitation) and winter (snow cover) conditions. Finally, we show the annual carbon budget of both sites, with a specific focus on the long-term impact of the drainage on carbon cycle process.
Application of a new magnetospheric field model to 3-D inversion of Swarm magnetic data in terms of mantle electrical conductivity
Authors: Velímský Jakub , Martinec Zdeněk
Published: February 2023

The large-scale electrical conductivity structures in the deep Earth's mantle, in the depth range of 670 to 1400 km, can be in principle determined from Swarm-observed induction response to time-variable magnetospheric currents (Velímský & Knopp 2021). However, these efforts have been so far encumbered by limited spatio-temporal description of the magnetospheric field from moving satellite platforms. In particular, the polar electrojets (PEJs) and field-aligned currents (FACs) are sources of a strong bias in the spherical-harmonic analysis of Swarm magnetic data. An electric circuit model of PEJs and FACs (Martinec & Velímský 2022) provides a novel data processing tool to suppress the bias and obtain a reliable model of the large-scale magnetospheric field during magnetically disturbed times. In this contribution we apply the new magnetospheric field model to the 3-D time-domain  forward and inverse modelling of global electromagnetic induction. We determine its impact on the sensitivity and resolution of the inverse problem, and proceed with regularized 1-D and 3-D inversions to update the electrical conductivity model of the deep mantle. 
The Copernicus European Ground Motion Service (EGMS) validation: a landslide monitoring prospective.
Authors: Vecchiotti Filippo , Kociu Arben
Published: February 2023

The advent of the EGMS service offers chances and opportunities to EU Member States practitioners and researchers into the field of landslide monitoring. As member of the EGMS validation team, under the lead of SIXENSE, the Geosphere Austria carried out the in situ validation activity for five test sites spread over Europe. The focus of this paper is the inter-comparison of an automatic geodetic monitoring system installed at two landslide locations in Tyrol, Austria against the main products offered by the EGMS:level 2a
level 2b
level 3
The comparison was performed in a Jupiter hub environment created ad hoc for the validation project by our partner Terrasigna. The workflow was developed in R language and validates error, precision and accuracy of the (in-situ) velocities and time series (TS) against the correspondent MT-InSAR values of the EGMS.The workflow is made of several highly customisable modules:reads and visualises the two datasets;
performs a series of analysis such as smoothing (simplification), outliers search and trends for both time series;
inter-compares all the combinations of derived TS datasets and calculates for each couple RMSE, Coefficient of Determination (R2) and index of agreement;
plots the TS and bar diagrams of the best scores in terms of minimum errors, maximum accuracy and maximum precision;
delivers a Quality Index (QI) between 0-1 for each EGMS product;
The results of the in-situ validation activity will be presented and explained. In fact, considering the type of natural hazard (deep-seated gravitational slope deformation) and his location (vegetated and high relief alpine morphology), this validation set the perfect example to discuss strength and weakness of the EGMS if compared to state-of-the art in-situ monitoring systems installed in such extreme and remote areas. 
Moisture Recycling in the Amazon: a study using WRF with water vapor tracers
Authors: Domínguez Francina , Eiras-Barca Jorge
Published: February 2023

This work analyzes the sources, sinks and stores of moisture that originates as Amazonian evapotranspiration (ET) from daily to annual timescales. To do this, we use the Weather Research and Forecast (WRF) regional meteorological model with the added capability of water vapor tracers to track the local evapotranspired moisture. The tracers reveal a strong diurnal cycle of Amazonian water vapor which had not been previously reported. This signal is related to the diurnal cycle of ET, convective precipitation and advected moisture. ET's contribution to atmospheric moisture increases from early morning into the afternoon. Some of this moisture is rained out through convective storms in the early evening. Later in the night and following morning, strong winds associated with the South American Low Level Jet advect moisture downwind. The beating pattern becomes apparent when visualizing the Amazonian water vapor as an animation.
Estimation of potential gas hydrate resources based on the geophysical data in the western continental margin of the Chukchi Plateau, the Arctic Ocean
Authors: Choi Youngil , Kang Seung-Goo , Choi Yeonjin , Hong Jong Kuk
Published: February 2023

Gas hydrates are known to be an enormous potential energy resource that are accumulated worldwide, especially in the polar regions, and yet the estimates for this resource remain uncertain. In the Arctic region, methane emissions into the atmosphere are a substantial factor in global warming that poses a great danger to the environment. Previously, several studies have been conducted to estimate the gas hydrates in the Arctic to ease such problems despite the need for more data compared to conventional reserves. In the western continental margin of the Chukchi Plateau, the sea mound morphologies were first discovered, and gas hydrate samples were obtained via gravity coring during the first expedition in 2016. In the following expedition in 2018, an intensive gas hydrate exploration including the single-channel seismic survey was conducted in the area of mound morphologies and identified the local bottom simulating reflectors. Consequently, an extensive multichannel seismic survey was conducted in 2019 to investigate the geophysical characteristics of widely distributed gas hydrates in the western continental margin of the Chukchi Plateau. The objective of this study is to estimate the potential volume of gas hydrate resources in the Chukchi Plateau based on the geophysical data. From this study, the distribution of bottom-simulating reflectors and local gas hydrate saturations were derived from the geophysical data. The gas hydrate saturation model in this study area was constructed using the kriging method with few geological assumptions. Then, the total volume of gas hydrates in the western continental margin of the Chukchi Plateau was proposed. The results of this study will provide basic information on the estimates of gas hydrates in the western continental margin of the Chukchi Plateau and contribute to assessing the size of the associated volume of methane emissions due to global warming.
Improved catalog of NOx point source emissions (version 2)
Authors: Beirle Steffen , Borger Christian , Jost Adrian , Wagner Thomas
Published: February 2023

We present an updated (v2) catalog of NOx emissions from point sources as derived from TROPOMI measurements of NO2 (PAL product) combined with wind fields from ERA5.Several improvements have been introduced to the algorithm. Most importantly, several corrections are applied, accounting for the effects of plume height on satellite sensitivity, 3D topographic effects, and the chemical loss of NOx, resulting in considerably higher and more accurate NOx emissions. In addition, error estimates are provided for each point source.        The catalog v2 is based on a fully automated iterative detection algorithm of point sources worldwide.It lists 1139 locations that have been found to be significant NOx sources.The majority of these locations match to power plants listed in the global power plant database.Other NOx point sources correspond to cement plants, metal smelters, industrial areas, or medium-sized cities.        The emissions listed in v2 of the catalog show good agreement (within 20% on average) to emissions reported by German Environment Agency (Umweltbundesamt, UBA) as well as the United States Environmental Protection Agency (EPA). 
Monitoring underwater volcanic degassing using Exail (iXblue) SeapiX volumetric sonar
Authors: Jouve Guillaume , Caudron Corentin , Matte Guillaume , Mosca Frédéric , Gauthier Tehei , Veloso Mario
Published: February 2023

Volcanic gases are a main trigger of explosive eruptions, but the largest amounts are emitted through passive, non-eruptive, degassing during quiescence. It is thus necessary to accurately map bubble clouds, and to monitor their dynamics, to reduce volcanic risks.Contrary to atmosphere, gases are easily detected in water column, particularly using hydro-acoustic methods (Vandemeulebrouck et al., 2000). Two pioneering studies have monitored gas venting into Kelud Crater Lake (Indonesia) from a hydroacoustic station shortly before a Plinian eruption in 1990 [1] and, nearly two decades later, by empirically quantifying CO2 fluxes using acoustic measurements in the same lake just before a non-explosive eruption [2]. However, despite hydroacoustic detection capabilities, fundamental advances are limited by technology performances. Overall acoustic detection of a bubble field is easy, while its quantification remains complex due to the 3D structure of clouds and the acoustic interactions between bubbles.We present results from near-surface geophysics of sedimentary deposits and water column gas seepage at the Laacher See (Eifel, Germany), using Exail Seapix 3D multibeam echosounder & Echoes high-resolution sub-bottom profiler. Backscatter profiles of water column elements distinguish macrophytes, gas bubbles and fishes and highlight several bubble plumes. Target Strength (TS) of bubbles is centered around -70 dB, suggesting they are of very small size (35 μm), much smaller than observed elsewhere using single beam echosounders. This would explain why, in the same spot, we did not observe any gas bubbling using camera mounted on ROV. Recent measurements at the nadir of a gas flare, in static positioning, using the steerable mills cross multibeam capability of the SeapiX, offered a 4D observation of the gas bubbling. It also provided an equivalent TS of the bubbling we observed two years earlier. We will also present CO2 flow rates that were also extracted from backscatter of gas bubbling in 4D. These calculations are currently being constrained using different backscatter models and represent the last technical aspect before developing an efficient early warning system. Meanwhile, Echoes 10 000 provides high-resolution paleoenvironmental reconstruction using 3D modeling of remobilized materials, and gas diffusion through the sediment. Fusion of all geophysical data using Delph Roadmap allows 3D modeling of gas flare dynamic from 40m in sediment to water-atmosphere interface. Our scientific approach contributes to improve forecasting of volcanic and limnic eruptions and participates to improve early warning systems by constant collaborations with academic research.[1] Vandemeulebrouck et al (2000) J. Volcanol. Geotherm. Res 97, 1-4: 443-456[2] Caudron et al (2012) JGR: Solid Earth 117, B5
Chinese Coal Mines Methane Emissions Constrained by High-Frequency Measurements
Authors: Hu Wei , Qin Kai , He Qin , Cohen Jason Blake
Published: February 2023

Methane’s high Global Warming Potential (GWP) and short atmospheric life relative to carbon dioxide have led to methane mitigation as a cost-effective and realistic near-term action that serves as a bridge to longer-term mitigation options. This paper calculated coal mine methane (CMM) emissions from 636 individual coal mines in Shanxi Province based on the Intergovernmental Panel on Climate Change (IPCC) Tier 2 approach. 5 sets of emission factors were used to compile this bottom-up inventory. Each coal mine is classified into 3 different coal mine gas ranks based on the method issued by the National Coal Mine Safety Administration and the National Energy Administration. Haft-hourly eddy-covariance measurements of methane flux from 1 mine (xhv) over a 5-month period were used to quantify and constrain the high-frequency variation in emissions. From the perspective of probability density, 15.5% of the total data is covered by the boxes overlapping the different bottom-up emissions estimates, while 53.5% of the total data falls in the single box below the floor of the bottom-up measurements. The in-situ measurements offer scaling factors (RATIO correction) for updating the preliminary bottom-up coal mine methane emissions datasets. A statistical approach is applied to individual coal mines by grouping them by coal mine gas rank. From the perspective of cumulative probability, the CMM flux shows a pattern that low gas rank < high gas rank < outburst rank. We have compared the CMM emissions with EDGAR-COAL and GFEI. In 2019, the EDGAR and GFEI inventory results show that methane emissions from coal mines in Shanxi Province are 7.27 Tg and 6.29 Tg, respectively. Our results range from 4.41-7.63 Tg. In Changzhi city, over the region in which this dataset has emissions that EDGAR-COAL and GFEI do not identify the emissions are [44.35,125.60,354.02] and [398.22,1125.81,3185.22] with the unit in ug (m-2 s-1), respectively. The values in brackets are results after RATIO correction, corresponding to cumulative percentages 30, 50 and 70 respectively. Over the region that EDGAR-COAL has misidentified coal mines, the emissions are 128.27 ug (m-2 s-1). Over the region that EDGAR and our inventory both have emissions, the EDGAR-COAL emissions are 357.65 ug (m-2 s-1), while our emissions are about 353.87 ug (m-2 s-1). Over the region where GFEI has misidentified coal mines, the emissions are 181.18 ug (m-2 s-1). Over the region that GFEI and our inventory both have emissions, the GFEI emissions are 164.04 ug (m-2 s-1). There are no regions where we have emissions while GFEI has no emissions in Changzhi city. These facility-level inventories can help identify mitigation opportunities at specific mines, and support the design of more effective policies.
Microbial hydrocarbon uptake and the effect of hydrocarbons on microbial sulfate reduction
Authors: Nagakura Toshiki , Morono Yuki , Ito Motoo , Kallmeyer Jens
Published: February 2023

Guaymas Basin, located in the Gulf of California, Mexico, is a young marginal ocean basin with high sedimentation rates of >1 mm/year, active seafloor spreading, and steep geothermal gradients in its sediment. It hosts a unique subseafloor biosphere as these conditions lead to the thermal cracking of sedimentary organic matter and the production of bioavailable organic carbon compounds and hydrocarbons already at shallow depths. The abundance and diversity of potential microbial substrates raise the question of which substrates are being used for catabolic and anabolic microbial metabolism. We thus analyzed the microbial uptake of hydrocarbons using nanoscale secondary ion mass spectrometry (nano-SIMS) analysis after incubation with stable-isotope labeled substrates. Incubations were carried out with samples from two IODP Exp. 385 drill sites, Site U1545 with undisturbed sedimentary strata and a temperature gradient of 225°C/km, and Site U1546 with a sill intrusion led to temporary heating of the sediment. The temperature gradient of 221°C/km indicates thermal equilibration with the surrounding sediment since sill emplacement. Incubations were carried out with 13C-benzene + 2H-hexadecane or 13C-methane at in-situ temperature (4-62°C) and pressure (25 MPa) for 42 days. Additionally, sulfate reduction rates (SRR) were measured by incubating the samples with four aliphatic hydrocarbons + four aromatic hydrocarbons or methane and radioisotope-labeled 35SO42- at in-situ temperature (4-63°C) and pressure (25 MPa) for 10 days. The nano-SIMS analyses reveal that a few samples showed detectable microbial assimilation of hydrocarbons. Nitrogen (from 15NH4Cl in the medium) was assimilated in some samples incubated with methane. The assimilation mostly occurred in samples from near the seafloor (2 and 44 mbsf). We hypothesize that the relatively short incubation time of 42 days was insufficient to detect extremely small incorporation rates in deep sediments. The results of the SRR measurements indicate that a mixture of hydrocarbons and methane increases the SRR in samples from near the seafloor (2 mbsf) and around the sulfate-methane transition zone (44 and 55 mbsf) but not in samples from greater depths. Our results show that anaerobic microorganisms in Guaymas Basin can use hydrocarbons for anabolic and catabolic metabolism in this extreme environment.
The role of ensemble learning in multi-optimization for streamflow prediction
Authors: Wang Dagang
Published: February 2023

The objective function plays an important role in the training process for deep learning models, since it largely determines the trained values of the model parameters and influences the model performance. In this study, we establish two application-orientated objective functions, namely high flow balance error (HFBE) and transformed mean absolute percentage error (MAPE*), for the forecasts of high flows and low flows, respectively, in the LSTM model. We examine the strength and weakness of these streamflow forecast models trained on HFBE, MAPE* and mean square error (MSE) based on multiple performance metrics. Furthermore, we propose the objective function-based ensemble model (OEM) framework that integrates the models trained on different objective functions, so as to take advantages of the trained models focusing on different aspects of streamflow and thus achieve a better overall performance. Our results in 273 catchments over USA show that the models trained on HFBE can alleviate underestimation in high flows existing in the models trained on MSE, and perform remarkably better for high flows. It is also found that the models trained on MAPE* outperform the other two models in low flow forecast, no matter what algorithm is used for the model establishment. By incorporating the three models trained on HFBE, MAPE* and MSE, respectively, our proposed OEM performs well in the forecasts of both high flows and low flows, and realistically capture the mean and the variability of the observational streamflow under different scenarios under a variety of hydrometeorological conditions. This study highlights the necessity of applying application-orientated objective functions for given projects and the great potential of the ensemble learning methods for multi-optimization in hydrological modeling.
Investigating the Changing Heavy Rainfall Climatology of North East India
Authors: Chakravorty Aniket , Kundu Shyam Sundar , Aggarwal Shiv Prasad
Published: February 2023

The increase in the variability of rainfall as the climate of the world warms up is a concern for many regions. Studies in the past have associated this change in variability to rise in heavy rainfall events. Thus a regional analysis of heavy rainfall characteristics to evaluate its response to a changing climate becomes important. In this study, we are putting this focus on the North East Region (NER) of India, which boasts of being one of the wettest regions of the world. This study examines the heavy rainfall characteristics from 1901 till 2020 over NER using the IMD gridded daily rainfall product. The examination showed that although the annual and monsoonal rainfall over the NER has been decreasing, the intensity of heavy rainfall has increased by ~5mm over the decades. Singular Spectrum Analysis is used to identify the long-term trend, which showed a change in heavy rainfall characteristics around 1970 and hence further investigation is carried out over two time blocks (Pre-1970: 1901-1970 and Post-1970: 1971-2020). The investigation of the frequency of heavy rainfall events showed that its increasing trend, prior to 1970, transitions to a decreasing trend, post 1970. It also showed that the area under a negative trend of frequency has increased significantly after 1970. Furthermore, a non-parametric probability distribution approach has also been implemented to interpret the frequency and intensity relationship of heavy rainfall together. This showed that post 1970, the probability of occurrence of a very heavy or extreme rainfall events has increased. The increase in probability did show a spatial variability. The increase in probability is more for the pre-monsoon season compared to the monsoon. This finding corresponds to the fact that the contribution of pre-monsoon rainfall to annual rainfall has increased while that of the monsoon rainfall has decreased over the decades. To investigate the local causes of the observed changes, the 2m temperature (T2), 2m Dew-point temperature (TD2) are investigated using a cross-sample entropy analysis. Interestingly, both T2 and TD2 showed a significant increasing trend over NER. Coincidentally, locations with increasing heavy rainfall intensity and frequency are also the locations with increasing TD2. Also, the pre-monsoon show a stronger increase in TD2, i.e., more moisture is available for convection, compared to T2, which could explain the higher probability of heavy rainfall events. Thus, increasing intensity and decreasing frequency can be explained by the inter-relationship between T2, TD2 and the convective processes.
Natural and social patterns in the distribution of Bronze Age Nuragic sites (Sardinia, Italy): using the Widom-Rowlinson penetrable sphere model to understand past human occupation
Authors: Mariani Guido Stefano , Brandolini Filippo , Melis Rita
Published: February 2023

When looking into land use and human agency in the modification of the landscape, the concepts of socio-economic opportunities vs. natural constraints is one of the key issues. In comparison with the modern world, past human communities relied much more upon local resources and a tight societal structure to better adapt to the conditions and changes in the surrounding environment. Therefore, in the study of prehistorical cultures land use is both a strong source of information about sustenance strategies and community behaviours and a subject potentially easier to model within a set of natural and social parameters. To this purpose, we investigated the settlement distribution patterns of Bronze Age structures of the Nuragic culture on the island of Sardinia (Italy) using spatial point pattern analysis. We investigated different covariates divided into natural (topography, water and geological resources) and cultural (type of structure, settlement hierarchy), alone and in combination, and looked at how each could explain the distribution of Nuragic sites.Several covariates from both natural and cultural groups show significant values, with the best representing models of pattern distribution coming from the combination of covariates from both groups. Aside from topographic parameters, distance from known ore deposits seems to have an impact on structure density. Among cultural covariates, there is a clear association between simple and complex megalithic structures (nuraghes). This pattern suggests the collation of smaller structures around larger settlements, either by the former emerging from the presence of the latter or vice versa. These findings offer new insight on the development and ways of life of the Nuragic society in their geographical context, and highlight how the relationship between the physical and the social aspects of human-landscape interactions is fundamentally interdependent. This approach could also represent a potential tool to compare to other Bronze Age and prehistorical communities.