bluuebunny/crossref_metadata_2025 huggingface dataset:
Smart Management of Emergency Shelter and Resilient Community
Authors: Ke Kai-Yuan , Tsai Meng-Han , Tan Yih-Chi , Lai Ming-Chia , Jhou Guan-Han , Chang Tzu-Ling
Published: February 2023

Volunteers are very important workforce during disaster events. In Taiwan, there are mainly two types of volunteers in terms of disaster management. One is the affiliated volunteer trained by the local government sectors, such as the police department, fire department, public affairs department, and social welfare department. The other is the spontaneous volunteer joining resilient community. Whether affiliated or spontaneous, those volunteers could provide services in two aspects, such as disaster information collections and emergency shelter operation. Therefore, the Disaster Information Volunteer Collection Platform (DIVCP) and Smart Sheltering System (SSS) were developed to assist volunteers on those tasks. DIVCP is composed of 4 main modules, such as early-warning module, disaster information collection module, disaster information confirmation module, and visualization module. SSS is composed of 5 key functions, including shelter opening, ID generation, registration, supplies management, and digital billboard of refugees and supplies. Both DIVCP and SSS have its unique Line Bot functions to be friendly used by the volunteers. All the developed functions are practiced and validated through drills in the local government level and community level. It is expected that, with the technical tools, local government would have multiple access to disaster information and the demand of supplies and workforce during disaster be acquired more efficiently.
The Indian monsoon variability during the last two millennia and links to the tropical equatorial Pacific
Authors: Gandhi Naveen , Reddy Aannpureddy P. , Yadava Madhusudan G. , Krishnan Raghavan
Published: February 2023

In this study, we examines the variability of the Indian summer monsoon rainfall (ISMR) during the last two millennia using a near-annually resolved speleothem oxygen isotope record from Kadapa cave in peninsular India. The results show that the monsoon precipitation variations experienced a wet phase during the dark age cold period (DACP; ~250 – 800 CE) as evidenced from the progressive depletion of the δ18O values; followed by high amplitude variability during the medieval warm period (MWP; ~ 900 – 1300 CE), and drier monsoon conditions with enriched δ18O values during the edge of the little ice age (LIA; ~ 1500-1850 CE). It is further noted that the monsoon precipitation variability as observed in the Kadapa speleothem record during the last two millennia is corroborated by other speleothem and sediment records from the Indian subcontinent and adjoining oceanic areas. Analyses of reconstructed climate proxies, suggest that the intertropical convergence zone (ITCZ) during the DACP was stable and located relatively northward with pronounced La Niña conditions prevailing in the tropical Pacific. On the other hand, the high amplitude monsoon precipitation variations during the MWP appear to have resulted from multi-decadal fluctuations in the latitudinal position of the ITCZ, accompanied by enhanced activity of ENSO. Additionally the low monsoon precipitation during the LIA is found to be closely linked to a southward shift of the ITCZ, with precipitation reductions during the edge of LIA associated with volcanic cooling. Enriched and depleted δ18O values are consistent with the instrumental records of weakening and revival of monsoon precipitation during 1850-2000 CE and post-2000 CE, respectively.
Fire impacts on soil carbon in a non-fire adapted alpine forest
Authors: Torres Melissa , Poyntner Caroline , Chaudhuri Sampriti , Pignitter Marc , Schmidt Hannes , Hofmann Thilo , Sigmund Gabriel
Published: February 2023

An increase in fire-prone conditions in non-fire adapted regions is rooted in climatic and anthropogenic changes. Such pyrogeographical shifts are observable, for example, in alpine regions. In 2021, Austria, experienced a fire larger than 100 ha for the first time in a century in the Schneeberg-Rax mountain region. In depth understanding of post-fire effects on carbon cycling at such non-fire adapted sites is still scarce. To help close this knowledge gap, post-fire changes were investigated at the abovementioned site, including soil organic matter composition and soil chemical conditions. Samples were taken immediately after the fire, 3 months, 6 months and 12 months thereafter from four sampling sites. Selected sites consisted of 1. a pine forest affected by a crown fire, 2. a pine and beech mixed forest affected by a surface fire, and two non-fire affected controls with similar site conditions (vegetation, slope, altitude, and exposition). Samples were analyzed for pH, carbon content, elemental composition, leachable dissolved organic carbon and trace elements, organic matter composition, and environmentally persistent free radical concentrations. pH increased after the fire at both sites investigated. This increase was the strongest (up to 1.5 units) immediately after the fire but was still substantial 1 year after the fire. Carbon contents decreased approximately 2fold in the crown fire affected soil compared to the control soil, but remained similar between surface fire affected soil and the respective control. However, aromaticity of bulk carbon and the leachable fraction increased in both fire-affected soils, which can be related to the formation of pyrogenic carbon during the fire. Pyrogenic carbon is a highly aromatic and recalcitrant carbon pool produced during incomplete combustion of biomass. Pyrogenic carbon can also contain substantial amounts of environmentally persistent free radicals (EPFR), which can form reactive oxygen species, which can induce oxidative stress on microbiota. Our EPFR measurements showed an increase by at least 1.5 orders of magnitude of EPFR in fire affected soils. This study suggests that changes in soil carbon cycling can be expected following fires in non-adapted alpine forests. 
On the need for bias-adjusted CORDEX data: present day and future temperature characteristics over the Carpathians at regional and local level
Authors: Simon Csilla , Kis Anna , Torma Csaba Zsolt
Published: February 2023

Present research focuses on temperature change signals over the Carpathian Basin with a special focus on selected lowland and mountainous sub-regions. Under the framework of the international initiative called COordinated Regional Downscaling EXperiment (CORDEX): EURO-CORDEX and Med-CORDEX provide regional climate model (RCM) simulations targeting Europe. Simulation of near-surface air temperature from a mini-ensemble of high-resolution (0.11°) EURO and Med-CORDEX RCM climate change experiments are analyzed based on raw and bias-adjusted data. The mini-ensemble consists of 8 RCM simulations driven by 5 different general circulation models (GCMs) for the period 1976–2099 under the high-end RCP8.5 (representative concentration pathway) scenario. The high-resolution, homogenized and quality controlled CARPATCLIM was used as a reference dataset during the bias-adjustment procedure. The selected sub-regions cover 8 municipalities located at diverse altitudes: Bratislava, Budapest, Brassov, Debrecen, Hoverla, Novi Sad, Pécs and Poprad. The following near-surface temperature related climate indices assessed over the region of interest: summer days (SU), ice days (ID), frost days (FD), tropical nights (TR), the coldest day (TXn), the warmest day (TXx), the coldest night (TNn) and the warmest night (TNx). In general, TXx, TNx and TNn were overestimated by the raw simulations by 1–4 °C in the central part of the region, but an underestimation was found in the case of TNn and TXn in the Carpathians for the reference period (1976–2005), whilst bias-adjusted RCM data showed almost perfect match with observations. Accordingly, no best performing RCM is found for all indices. The ensemble mean of the bias-adjusted RCM simulations project an increase (decrease) in the annual number of SU and TR (FD and ID) for the near future (2021–2050) and for the far future (2070–2099). Profound warming manifests in the increase of TXx of up to 2–3 °C by the near future and of 5–7 °C by the end of the 21st century. Our results also highlight the need on bias-adjusted data applied by different sectors (e.g. human health, agriculture, transport, tourism, disaster management or heritage conservation) in the context of national adaptation strategies.
A new Permian-Triassic paleogeographic reconstruction for the East Asian blocks
Authors: Ren Qiang , Chen Anqing , Hou Mingcai
Published: February 2023

The East Asian blocks were important parts involved in Pangea formation, and their paleogeographic evolution during the late Paleozoic was controlled by two tectonic domains: the Paleo-Asian Ocean (PAO) and the East Paleo-Tethys Ocean (EPTO). Although some tectonic reconstructions of East Asia have been proposed, there has been a great contradiction between them and paleobiogeographic models during Permian. We have recently complied the Permian-Triassic East Asian paleomagnetic database and reconstructed the paleogeography of East Asia in combination with paleontological (e.g., data from the Paleobiology Database) and geological evidence. The new reconstruction for the East Asian blocks exhibited that the Xilinhot-Songliao Block was located between the eastern PAO and the EPTO during the early Permian and was the intermediate unit that separated the two tectonic domains. The Paleo-Tethys Ocean was a wider east-west range than most previous version. It strongly supports Torsvik et al. (2008)’s view that the absolute paleogeographic position of the South China Block reconstructed by the eruption of the Emeishan large igneous province (~260 Ma) at the margin of the Large Low Shear wave Velocity Provinces. During 265-255 Ma, the East Asian blocks moved rapidly northward, which probably accelerated the end‐Guadalupian mass extinction in East Asia. The PAO closed completely at 250 Ma, and thus the tectonic framework of the Northeast Asian continent was basically formed. Since then, East Asia began to transform into a new evolutionary stage of the superposition of multiple tectonic regimes: (1) the north Mongol–Okhotsk Ocean (between Siberia and Amuria) had sustained scissor-like closure from west to east during the Mesozoic period; (2) the east Paleo-Pacific oceanic plate had undergone westward successive subduction and accretionary since the early Mesozoic (e.g., formed the Nadanhada accretionary terrane and the Sikhote orogenic belt); (3) the southwest Tethyan blocks (e.g., North/South Qiantang, Lhasa, Indochina, Sibumasu) experienced a rapid northward movement accompanied by intense subduction and collision.
Ice slab thickening drives surface runoff expansion from the Greenland Ice Sheet’s percolation zone - and vice versa
Authors: Jullien Nicolas , Tedstone Andrew , Machguth Horst
Published: February 2023

On the Greenland Ice Sheet, the firn layer holds the potential to trap and refreeze surface meltwater within its pore space. Acting as a buffer, it prevents meltwater from leaving the ice sheet. However, several meter-thick ice slabs have developed in the firn during the last two decades, reducing subsurface permeability and inhibiting vertical meltwater percolation. Ice slabs are located above the long-term equilibrium line along the west, north and northeast coasts of the ice sheet. Through time, ice slabs have thickened while new ones have developed at higher elevations. Concomitantly, the area of the ice sheet drained by surface rivers has increased by 29% from 1985 to 2020. Nowadays, 5-10% of surface losses through meltwater runoff originates from these newly drained areas, which correspond strongly with where ice slabs are located.Here, we demonstrate that the highest elevation which is drained by surface rivers – termed the maximum visible runoff limit – is controlled by the ice content in the subsurface firn. Using ice slab thickness derived from the accumulation radar and annual maximum visible limit retrievals from Landsat imagery from 2002 to 2018, we show that a sub-surface ice content threshold triggers the shift from a ‘firn deep percolation regime’ to a ‘firn runoff regime’. Although ice slabs act as an aquitard, vertical meltwater percolation can still take place where visible meltwater ponds at the surface. We show that once the firn runoff regime is underway, ice slabs are thicker in locations with active surface hydrology compared to locations where no meltwater is visible at the surface. Spatial heterogeneity in ice slab thickness is therefore predominantly controlled by surface hydrology features.
Determining near surface roughness based on artificial precipitation experiments on natural hillslopes for the application in hydrodynamic flash flood modelling
Authors: Feldmann David , Laux Patrick , Heckl Andreas , Schindler Manfred , Kunstmann Harald
Published: February 2023

Flash floods resulting from torrential precipitation events cause devastating destruction and loss of human lives, as numerous events in Central Europe have demonstrated in recent years. To assess the damage potential of such events, using hydrodynamic 2D-models is the most accurate method to simulate all hydraulic and hydrological processes at the earth's surface.Beside infiltration, roughness is the key parameter for hydraulic surface runoff simulations. Particularly roughness for near surface runoff is affected by high uncertainties, as numerous available values are only valid for higher water depths. The choice of the roughness coefficient influences the flow velocity and therefore the accumulation of surface runoff. This potentially leads to an inaccurate planning of flood protection measures.Based on artificial rainfall experiments on natural hillslopes, available in literature, we estimate the roughness coefficient (Manning’s n). The experiments have been conducted on a wide range of different sites, whose properties differ in vegetation type (pasture, crops, bare soil), vegetation density (0-100%) and slope (10-30%). A framework evaluating rainfall intensity and surface runoff with the aim to separate the impact of infiltration rate and roughness on the shape of the hydrograph is developed. This avoids complex measurements of flow velocity and water depth during the field experiments.To verify the validity of the framework, three water depth-dependent formulations of roughness and a constant Manning coefficient are used to simulate the measured hydrograph with an idealized hydraulic 2D-model. This finally results in a robust parameterisation of near surface roughness for a water depth below 1 cm. A strong dependence of the roughness coefficient on the degree of vegetation cover and a correlation between rain intensity and roughness was found. In addition, the temporal change of the infiltration rate during the rainfall experiment could precisely be calculated through the determination of roughness. Therefore, the developed framework also allows a better calibration of infiltration models based on artificial rainfall experiments. In conclusion, this study reduces uncertainties in 2D-hydraulic flash flood modeling by providing empirical near surface roughness coefficients.
Progressive channel erosional processes of the 2020 Heixiluo debris flow in Dadu River, southwestern China
Authors: Hu Kaiheng , Ning Lan , Wei Li , Zhang Qiyuan
Published: February 2023

Debris flows are the common gravity-driven mass flows in mountain areas that have high sediment concentration, wide grain sizes, and strong impact force.  Erosion or entrainment is the main mechanism by which the flows significantly increase their volume and destructive potential when they progressively move down over colluvial or alluvial beds. However, the scale and mechanism of erosion are poorly understood due to scarcity of field data. We present on-site data of a rare event in which three consolidated landslide dams were incised deeply by debris flows in a small catchment, southwestern China. The highest erosion rate was up to 1.3 m/min or 568 m3 per unit channel length. The channel topographical condition controls transition from erosion to deposition and the locations of local erosion maxima. An outburst-flood erosion model incorporating flow discharge, channel slope and erodibility is adopted to simulate the progressive erosion of these dams. The infrequent case confirms the key role of debris flows in alpine landscape evolution and provides field data (case data) for developing advanced erosion models. This work provides new insights into the role and scale of debris-flow erosion in catchment evolution.
Random forest models based on Sentinel-2 multispectral indices for flood mapping
Authors: Albertini Cinzia , Petropoulos George P. , Gioia Andrea , Iacobellis Vito , Manfreda Salvatore
Published: February 2023

Optical satellite sensors represent a reference for Earth imaging applications, including land monitoring and flood management, directly allowing the visual interpretation of acquired scenes or the exploitation of surfaces’ spectral signatures. An extensive literature exists that proves the ability of multispectral satellite sensors in mapping flooded areas and water bodies (Albertini et al., 2022). Several multispectral indices have been developed for water segmentation in different contexts of varying degrees of landscape complexity. Simultaneously, the advancements in Machine Learning (ML) methods led to a proliferation of supervised and unsupervised algorithms applied to classification problems in the field of flood hazard and risk mapping. In the present study, four random forest (RF) models were used in combination with three spectral indices, namely the Modified Normalized Difference Water Index (MNDWI), the Normalized Difference Moisture Index (NDMI) and the Red and Short Wave Infra-Red (RSWIR) index, to map the extent of the flood event occurred along the Sesia River (Vercelli, Italy) in October 2020. A Sentinel-2 scene was acquired soon after the flooding event and spectral bands at 20m resolution were used in the analyses. The performances of the RF methods implemented with the use of the mentioned spectral indices were evaluated and compared using as reference map the delineation product delivered by the Rapid Mapping service of the Copernicus Emergency Management Service (CEMS). Results revealed some very interesting findings regarding the performances of the examined methods, which can become a well-established operational technique. Last but not least, the validation framework itself underlined the added value of Sentinel-2 and the Copernicus platform as a robust, rapid and cost-effective solution in flood mapping.Keywords: floods mapping, spectral indices, machine learning, Sentinel-2, ItalyReferences:Albertini, C.; Gioia, A.; Iacobellis, V.; Manfreda, S. Detection of Surface Water and Floods with Multispectral Satellites. Remote Sens., 14, 6005, 2022. (doi: https://doi.org/10.3390/rs14236005).
Quantifying the drivers of forest-based climate change mitigation
Authors: Gregor Konstantin , Krause Andreas , Reyer Christopher P.O. , Knoke Thomas , Meyer Benjamin F. , Suvanto Susanne , Rammig Anja
Published: February 2023

Besides offering numerous important ecosystem services, sustainably managed forests can help reduce atmospheric CO2 concentrations and thus mitigate climate change. Forest-based mitigation occurs through the carbon sink in the forest itself, the carbon sink in wood products, and through substitution effects when wood products replace carbon-intensive materials and fuels.The relative importance of each of these three mitigation dimensions depends on a multitude of factors. First, forest type and structure, site conditions, and climate change and associated disturbances determine the amount of carbon that may be sequestered over the next decades at a given site. Second, the type and intensity of management determines the trade-off between on-site carbon sequestration and carbon storage in wood products. Third, management, wood usage patterns, and the carbon-intensity of the economy determine the amount of avoided emissions via substitution effects.To assess their impact on the total forest mitigation potential, we conducted a factorial modeling experiment by varying all of the aforementioned factors. Specifically, we looked at the forest type (needle-leaved vs broad-leaved) and age (young vs mature), increased and decreased harvest intensities, increased material wood usage and cascading, decarbonization rates, climate change and disturbance scenarios, and salvage logging practices after disturbance.Under an assumed "closer-to-nature forest management" our results show a higher mitigation potential of young forests compared to mature forests, whereas the forest type does not have a clear effect. The importance of substitution effects outweighs the importance of the forest and product carbon sink on shorter time scales. This changes towards the end of the century, assuming that substitution effects decrease because the substituted materials can be produced in a less carbon-intensive way. Increases in harvest intensity consequently are also only beneficial for climate change mitigation on these shorter time scales, though they likely have adverse effects on other ecosystem services. Our results also show that increased material usage (as opposed to energy usage) of wood can be an important lever for mitigation. Finally, changes in disturbances strongly affect the mitigation potential, though the mitigation impact of a subsequent salvaging operation heavily depends on the forest type and the product portfolio created from the salvaged wood.In conclusion, our results quantify the impacts and interactions of the different factors that govern forest-based mitigation, while highlighting the complexity of the topic and the importance of the considered time-scales.
Categorization of mining waste based on geochemical and toxicological characterization data in restoration/remediation projects. Case study of the San Quintín Pb-Zn mine (Ciudad Real, Spain)
Authors: Ferri  Moreno Inmaculada , Barquero José Ignacio , Andreu-Sánchez Óscar , Higueras Pablo , García-Lorenzo Mari Luz , Esbrí José María
Published: February 2023

San Quintín is one of the derelict mines in Alcudia Valley Mining District, where large amounts of mining wastes have been disseminated during the last two centuries. These dumps and tailings materials are an important source of contamination of heavy metals and metalloids in the area. Nowadays, the restoration project for the abandoned mining area is beginning to be drafted, including a risk assessment of the wastes before restoration works. In this work, we carried out toxicity studies of these polluted materials, including data about total and soluble contain of As, Cd, Pb, Zn and Fe, mineralogical composition, and some bioassays to determine the toxicity effect of the samples to crustaceans (D. magna and T. platyurus) and algae (R. subcapitata). The pollution load index (PLI) has been calculated for each sample based on the pollution index (PI). Multielemental data and the indices calculated show that most of the samples present extremely high values of potentially toxic elements, and high values of contamination respect the background levels: 444 mg kg-1 Cd, 144,900 mg kg-1 Pb, 47,700 mg kg-1 Zn, 202,600 mg kg-1 Fe and 549 mg kg-1 As. The bioassays suggest a relationship with pH, conductivity and grainsize. The EC50 values were 458.7 to <2 of toxic units (TU) for D. Magna whereas for T. Platyurus the results oscillated between 2500 to <2. On the other hand, for algae organisms were 2083.3 to <2 TU. The studies carried out reveal the large accumulation of potentially toxic elements in mining waste and the risk they may pose to the associated ecosystems that develop in the area, as well as to human health.
First MAX- DOAS results of the SO292-2 cruise across the Pacific in June/July 2022: Nouméa (New-Caledonia) to Dutch Harbor (Alaska, USA)
Authors: Ziegler Steffen , Lauster Bianca , Beirle Steffen , Donner Sebastian , Wagner Thomas
Published: February 2023

Transit cruises of German research vessels across oceans provide a unique platform for MAX-DOAS measurements of atmospheric trace gases such as nitrogen dioxide (NO2), formaldehyde (HCHO) and sulphur dioxide (SO2). The Deep Blue/PORD campaign took place from 24 June to 21 July 2022. During that period the research vessel SONNE was crossing the Pacific in meridional direction from 22° S to 54° N in an area that is typically used as reference for satellite data due to its large distance from anthropogenic emission sources.In this study we focus on three trace gases: NO2 columns provide information on the meridional distribution of stratospheric NO2 as well as the distribution of tropospheric background NO2 above the marine boundary layer. For the analysis, high signal “peaks” that only last a short time are filtered as they most likely originate from the ship exhaust. First results show a minimum of total NO2 columns between the equator and about 15° N. HCHO and SO2 mainly appear as plumes from nearby islands and/or volcanoes in the Solomon Sea, where biogenic and volcanic activities are naturally high. In combination with the onboard instrumentation (Ceilometer, Pyranometer and a cloud camera) this data set provides a detailed description of the atmosphere along the cruise track.
Mineralogy, major and trace element geochemistry of rock-forming and rare earth minerals in the Bayan Obo (China) carbonatite dykes: implications for REE mineralization
Authors: Yang Jinkun , Song Wenlei
Published: February 2023

Rare earth elements (REE) have been a focus of global interest because of their irreplaceable role in developing “low carbon” technologies. The Bayan Obo is the world’s largest REE deposit, but its genesis is still highly debated. It is considered to have a close genetic association with carbonatite due to the presence of the carbonatite dykes around the orefield, as well as the geochemical similarities between these dykes and the orebody. However, the evolution of the carbonatite dykes and their REE mineralization are still poorly understood, hindering the interpretation of the genesis of the deposit. More than 100 carbonatite dykes have been found within the area of 0-3.5km nearby the orebodies of the deposit. These dykes show significant variations in mineralogy and geochemistry and were classified into dolomite (DC) and calcite carbonatite (CC). The rocks show an evolutionary sequence from DC to CC, and their corresponding REE contents increased remarkably, with the latter having very high REE content (REE2O3 up to 20 wt. %). The DC is composed of coarse-grained dolomite, magnetite, calcite, and apatite without apparent REE mineralization. The medium-grained calcites, and significant amounts of REE minerals, such as monazite, bastnäsite, and synchysite, make up CC. The REE minerals have a close relationship with barite, quartz, and aegirine. The REE patterns of dolomite and calcite in DC showed a steep negative slope with a strong LREE enrichment. In contrast, the calcite from CC has a near-flat REE pattern enriched in both LREE and HREE. Besides, apatite and magnetite in CC are characterized by strong REE enrichment compared to those from DC. Based on detailed petrology, mineralogy, and element geochemistry, we propose that strong fractional crystallization of initial carbonatitic melts led the REE enriched in the residual melt/fluid to form REE mineralization. In addition, sulfate, alkalis, and silica components play an important role in REE transportation and precipitation.
Increasing chances of summer wildfires in the UK?
Authors: Thompson Vikki , Mitchell Dann , Bloomfield Hannah , Dunstone Nick , Kay Gillian
Published: February 2023

In the summer of 2022 unprecedented weather conditions in the UK lead to wildfires in many regions. Record breaking temperatures – above 40 °C for the first time - and prolonged dry conditions led to exceptional fire weather severity. On July 19th London Fire Brigade declared a major incident as firefighters battled several significant wildfires across the city. We investigate if climate change is enhancing summertime wildfire risk in the UK. We use reanalysis data from 1960 to the present day to analysis trends in the climatic indicators that influence the fire weather index. A large ensemble of initialised climate model simulations from the same time period are used to support the findings and identify as-yet-unrealised possible fire weather index situations in the UK. In the UK the term ‘wildfire’ is not limited to fires in wildland, but to any uncontrolled vegetation fire which requires action regarding suppression. Wildfires in the UK are considered a semi-natural hazard due to their close link with human activity. Though we investigate only meteorological influences, these are not the sole cause of wildfires – for example fuel availability plays a large role. Better understanding of the trends in the fire weather severity and chance of exceptional conditions for the UK will enable improved understanding of the risks. This information can feed into relevant policy and contingency planning, allowing society to become better prepared for the future as the planet continues to warm. 
Sources of marine debris for Seychelles and other remote islands in the western Indian Ocean
Authors: Vogt-Vincent Noam , Burt April , Kaplan David , Mitarai Satoshi , Turnbull Lindsay , Johnson Helen
Published: February 2023

Vast quantities of debris are beaching at remote islands in the western Indian Ocean, despite minimal or zero local sources of pollution. We carry out marine dispersal simulations, informed by observations, incorporating currents, waves, winds, beaching, and sinking, for both terrestrial and marine sources of debris, to predict where this debris comes from. Our results show that most terrestrial debris beaching at these remote western Indian Ocean islands drifts from Indonesia, India, and Sri Lanka, although we also find evidence that a large fraction of bottles polluting these islands may have been discarded from fishing vessels and ships transiting the Indian Ocean. Abandoned, lost or otherwise discarded fishing gear (ALDFG) associated with purse-seine fisheries likely originates from within the western Indian Ocean, but ALDFG from longline fisheries may be sourced from further afield. Debris accumulation rates at Seychelles are likely seasonal, peaking during February-April. This pattern is driven by monsoonal winds and may be amplified during positive Indian Ocean Dipole and El-Nino events. We make suggestions for future beach clean-up operations, and also recommend that observational campaigns intending to identify sources of debris accumulating at remote islands should either target beaches that are not subject to regular clean-ups, or monitor accumulation over multiple years. Our results underline the vulnerability of small island states to marine plastic pollution, and are a crucial step towards improved management of the issue. The trajectories used in this study are available for download, and our analyses can be rerun under different parameter choices.
Evaluating the Impact of Blanket Peatland Restoration on Carbon Dynamics using 3D X-ray Micro-Computed Tomography
Authors: Brennand Jack , Carr Simon , Evans Elizabeth
Published: February 2023

Peatlands are the second largest global store of carbon and represent the most efficient terrestrial carbon store on the planet. ~13% of the world’s blanket peatlands are located in the UK, and they play a potentially crucial role in regulating climate. It is estimated that they store ~3.12 billion tonnes and sequester ~5.5 million tonnes of carbon per year, equivalent to ~1% of the UK’s total annual greenhouse gas emissions. However, unsustainable anthropogenic exploitation of blanket peatlands has resulted in ~90% of the known extent in the UK categorised as being in poor condition under the Joint Nature Conservation Committee standards. This is a consequence of these peatlands experiencing cutting, overgrazing, burning, drainage, and erosion. Due to these anthropogenic disturbances, UK blanket peatlands are suggested to emit ~10 million tonnes of carbon per year, representative of ~2% of the UK’s total annual greenhouse gas emissions. In response, the UK Government has incorporated peatlands in national level policy through the setting of restoration targets under climate change commitments. However, restoration targets are not being met and there are no ‘hard’ policies for blanket peatland restoration specifically. This is partly due to a lack of primary research into the effectiveness of peatland restoration.This study explores the interactions between peat structure and peat function, which is indicative of carbon sequestration and storage (carbon dynamics), in restored blanket peatlands under different treatments and timescales in Cumbria, England. 3D X-ray Micro-Computed Tomography (µCT) is applied to peat core samples from natural, degraded, and restored blanket peatlands to visualise and quantify the internal structure of peat soils at a 0.51µm resolution. Structures include; 1) air filled and water filled pore networks; 2) air filled and water filled root networks; 3) peat matrix density; and 4) other organic matter developments which regulate the carbon dynamic function of peat soils. For the first time, this study will identify and evaluate the impact of blanket peatland restoration on peat structure and function. The investigation is also reinforced with bulk chemical and field monitoring datasets. These are integrated with the µCT outputs to understand the response of carbon dioxide and methane dynamics to blanket peatland restoration.
Aerosol Optical Depth Measurements and trends from the Global Atmospheric Watch - PFR Network and aerosol homogenization initiatives
Authors: Kazadzis Stelios , Kouremeti Natalia , Groebner Julian
Published: February 2023

Multiwavelength aerosol optical depth (AOD) has been defined as an essential climate variable for the Global Climate Observing System (GCOS) and the Global Atmosphere Watch (GAW) Program of the World Meteorological Organization. It is the most important parameter related to aerosol radiative forcing studies. PMOD/WRC have developed the Precision Filter Radiometer (PFR) that has been used for long term AOD measurements under a GAW-PFR Network of sun-photometers started in 1995 at Davos Switzerland and from 1999 at other locations, worldwide.Here we present an overview of the stations measurements till 2021 including station statistics and AOD trends.An overview of the results of the long term GAW-PFR AOD series for four high altitude stations (Izana/Spain, Mauna Loa/USA, Mt. Walliguan/China and Jungfraujoch/Switzerland). Mean AODs at 500nm were from 0.01 up to 0.1 with small negative changes per year for all stations.Also we present an overview of the homogenization activities performed by the world aerosol optical depth research and calinration center (WORCC) towards a harmonization of AOD measurements worldwide and some examples on uncertainties and effects on global trend analysis and satellite AOD validation initiatives.
Benthic dissolved silicon and iron cycling at glaciated Patagonian fjord heads
Authors: Hendry Katharine R , Ng Hong Chin , Hawkings Jon , Bertrand Sebastien , Summers Brent , Sieber Matthew , Conway Tim , Sales de Freitas Felipe , Ward James , Pryer Helena , Wadham Jemma , Arndt Sandra
Published: February 2023

Glacier meltwater supplies a significant amount of silicon (Si) and iron (Fe) sourced from weathered bedrock to downstream ecosystems. However, the extent to which these essential nutrients reach the ocean is regulated by the processes occurring within fjords, which act as conduits from glacial rivers and subglacial discharge and the ocean. One key – but understudied – component of biogeochemistry within fjords is benthic cycling, especially in regions of rapid deposition of reactive particulates at fjord heads. Here, we explore the benthic cycling of Si and Fe at four Patagonian fjord heads through geochemical analyses of sediment pore waters, including stable Si and Fe isotopes (δ30Si and δ56Fe respectively), and novel reaction-transport modelling for Si. A high diffusive flux of dissolved Fe from the fjord sediments compared to open ocean sediments is supported by both reductive and non-reductive dissolution of glacially-sourced reactive Fe phases, as reflected by the range of pore water stable Fe isotopes (δ56Fe from -2.7 to +0.8‰). In contrast, the diffusive flux of dissolved Si from the fjord sediments is relatively low. High pore water δ30Si (up to +3.3‰) observed near the Fe(II)-Fe(III) redox boundary is likely associated with the removal of dissolved Si by Fe(III) mineral phases, which, together with high sedimentation rates, contribute to the low diffusive flux of Si at the sampled sites. Our results suggest that early diagenesis promotes the release of dissolved Fe but suppresses the release of dissolved Si at glaciated fjord heads. The redox sensitive coupling of Si and Fe has significant implications for our understanding of how essential nutrients are transport along fjord systems.
Resolving capabilities of 3D electrode configurations for spectral induced polarization surveys
Authors: Moser Clemens , Flores Orozco Adrian , Binley Andrew
Published: February 2023

The induced polarization (IP) method is an extension of the electrical resistivity method that allows the measurement of both the electrical conductive and capacitive properties of the subsurface; it is one of the main methods applied in landfills to characterize the geometry and composition of waste as well as the migration of leachate. Commonly, landfill IP investigations are based on measurements along several 2D lines. Considering the complexity of landfills, we investigate here the resolving capabilities of 2D parallel electrode lines with inline measurements, and 3D electrode configurations (grid array with electrodes set in a quadratic mesh and circular array with electrodes set in four concentric circles) through a numerical study and field measurements. The field surveys were conducted on two landfills with different waste composition, with measurements in the frequency range between 1 and 240 Hz to solve the frequency-dependence of the electrical properties. The results of both the numerical study and the field data show a lack of sensitivity in the case of the 2D configuration leading to the creation of artefacts in the conductivity magnitude and phase imaging result. An underestimation of IP values is also seen for these arrays; such effects are particularly critical in the case of heterogeneously distributed IP anomalies, which are typical in landfills. In contrast, the tested 3D configurations are able to resolve the geometry of the electrical units correctly and anomalies are more sharply defined compared to the results obtained by 2D configurations. Furthermore, our results show that the grid array with crossline measurements and multiple dipole orientations provides better results than the circular array, which lacks in the resolution in the central area. Additional investigations of the frequency-dependence of the field data demonstrate that for the different study areas only 3D configurations provide smooth spectra of the conductivity magnitude and phase, which is essential for an accurate estimation of relaxation (e.g., Cole Cole) parameters.
Measuring volcanic ash optical properties with high-spectral resolution infrared sounders: role of refractive indices
Authors: Deguine Alexandre , Clarisse Lieven , Herbin Hervé , Petitprez Denis
Published: February 2023

Hyperspectral infrared sounders like IASI are used to track and quantify volcanic ash in the atmosphere. The retrieval process of physical quantities like particle radius and mass depends critically on the assumed spectrally dependent complex refractive indices that are used. Traditionally, the Pollack et al. (1973) dataset were used almost exclusively. These indices are however based on measurements of rock slabs and in recent years two datasets have become available from laboratory measurements of ash in suspension, the Reed et al. (2018) and Deguine et al. (2020) dataset. In this work, we compare for the first time the three most important datasets of CRI with respect to the three most common ash types (basaltic, andesitic and rhyolitic). The results show significant influence of the dataset used on the retrieved physical quantities. When it comes to basaltic and andesitic ash, both the Deguine and Reed samples outperform Pollack in terms of able to reconstruct the satellite observed spectra. However, all datasets overestimate the extinction near 1250 cm−1, which could possibly be related to the lack of sensitivity of spectrometers (water vapour continuum) leading to a poor signal over noise ratio in this spectral region. While this is not a guarantee that the retrieved quantities are closer to the physical reality, being able to reconstruct the observed spectra is a prerequisite of constructing a consistent physical model. Finally, a case study on the 7 May 2010 plume of the Eyjafjallajokull eruption is presented. For this case study, the differences are found to be mostly related in retrieved altitudes. It is clear that while the availability of CRI based on ash suspended in air is an important milestone, a lot of further research is needed to strengthen the theoretical basis of infrared retrievals of volcanic ash. A comprehensive database of reliable in-situ measurements of volcanic clouds would in this perspective be most welcome.A. Deguine, D. Petitprez, L. Clarisse, S. Gudmundsson, V. Outes, G. Villarosa, and H. Herbin, “Complex refractive index of volcanic ash aerosol in the infrared, visible, and ultraviolet,” Applied Optics, vol. 59, no. 4, p. 884, jan 2020.J. B. Pollack, O. B. Toon, and B. N. Khare, “Optical properties of some terrestrial rocks and glasses,” Icarus, vol. 19, no. 3, pp. 372–389, jul 1973.B. E. Reed, D. M. Peters, R. McPheat, and R. G. Grainger, “The complex refractive index of volcanic ash aerosol retrieved from spectral mass extinction,” Journal of Geophysical Research, vol. 123, no. 2, pp. 1339–1350, jan 2018.
Advancing research on compound weather and climate events via large ensemble model simulations
Authors: Bevacqua Emanuele , Suarez-Gutierrez Laura , Jezequel Aglae , Lehner Flavio , Vrac Mathieu , Yiou Pascal , Zappa Giuseppe , Zscheischler Jakob
Published: February 2023

Societally relevant weather impacts typically result from compound events, which are rare combinations of weather and climate drivers. For example, compound hot-dry events frequently cause damage to human and natural systems, often exceeding separate impacts from heatwaves and droughts. Focussing on four event types arising from different combinations of climate variables across space and time, we illustrate that robust analyses of compound events – such as frequency and uncertainty analysis under present-day and future conditions, event attribution, and exploration of low-probability-high-impact events – require very large sample sizes. In particular, the required sample is much larger than that needed for routinely considered univariate extremes. We demonstrate how large ensemble simulations from multiple climate models are crucial for advancing our assessments of compound events and for constructing robust model projections. For example, among the case studies, we focus on compound hot-dry events and show that large ensemble model simulations allow for identifying plausible extremely dry climates that, if occurring in a warmer world, would be associated with high risk from compound hot-dry events. Overall, combining large ensemble simulations with an improved physical understanding of compound events will ultimately provide practitioners and stakeholders with the best available information on climate risks.
Downward particle fluxes at south-eastern Fram Strait (Svalbard)
Authors: Langone Leonardo , Miserocchi Stefano , Bensi Manuel , Kovacevic Vedrana , Mansutti Paolo , De Rovere Francesco , Giordano Patrizia
Published: February 2023

Water masses in the eastern Fram Strait are strongly influenced by the interaction between Atlantic and Arctic waters, and by atmospheric forcing, thus contributing to drive the global thermohaline circulation. There is considerable variability in the system due to different forcing (e.g., atmospheric, internal, tidal, shelf dynamics) that play an important role especially in the uppermost layer of the ocean. On the contrary, it is not entirely clear which processes are responsible for the inter-annual and seasonal variability of the deep flow in the western Spitsbergen region.The oceanographic deep-sea mooring S1 has been deployed since 2014 on the continental slope offshore Storfjorden at a water depth of approx. 1000 m. In 2014-2016 and 2017-2018, a twin mooring (ID2) was also placed 140 km north of S1 at approximately the same depth in order to monitor spatial differences of the properties and dynamics of the water along continental slope.Short-term fluctuations of thermohaline properties and currents at 1000 m depth were repeatedly measured both at S1 and ID2 in different years. Such oscillations were related to the passage of internal waves and/or eddies by the passage of intense atmospheric storms, which in turn trigger intrusions of AW into the deep layer, with tricky effects on ecosystem functioning.Similarly to thermohaline properties, spatial and temporal fluctuations in total mass fluxes were also recorded. Annual particle fluxes ranged between 67 and 198 g m-2 y-1 at site S1, while  ID2 had approximatively twice the values of S1. Here, we discuss the drivers influencing the particle sources and the downward ﬂuxes in the eastern Fram strait.Peak values of particle fluxes occurred in late winter-early summer, in the same season of maximum variability of thermohaline properties. But, they were not perfectly synchronous with turbidity peaks. A time lag of a couple of months was detected between max turbidity and particle deposition in the sediment trap, when the currents slowdown. Actually, turbidity does not appear to be related to current speed, but to current direction (SE-NW). We suggest that upslope currents (E-ward), which occur during warm water intrusions, are able to resuspend bottom sediment at the shelf edge. From our dataset it is apparent that often (but not always) the water turbidity increases during the current rotation from eastward to the following NW direction.