bluuebunny/crossref_metadata_2025 huggingface dataset:
New constrains on infrasound source mechanisms within debris-flows
Authors: Belli Giacomo , Marchetti Emanuele , Gheri Duccio , Walter Fabian , McArdell Brian W.
Published: March 2022

Debris flows are episodic gravitational currents, consisting of mixtures of water and debris in varying proportions occurring in steep mountain catchments, with volumes commonly exceeding thousands of m3. Given their unpredictability and their capability to transport large boulders, debris flows rank among the most dangerous natural hazards in mountain environments.

The use of infrasound arrays and the combined use of collocated seismic and infrasound sensors have turned out to be efficient systems for reliable detection of debris flows in near real-time, highlighting the strong potential of infrasound for studying and monitoring debris-flows.

Despite these advances, open questions remain about the possibility to infer debris-flow source characteristics and event magnitude from recorded infrasonic signals. This requires theoretical and/or empirical source models describing elastic energy radiation in the atmosphere, in the form of infrasound, and relating it to fluid dynamic processes within a debris flow. Infrasound radiated by debris-flows is thought to be generated by standing waves that develop at the free surface of the flow, but details of the involved dynamic processes are not fully understood.

Here, we present the analysis of infrasonic signals from >20 debris flows and torrential floods recorded with a small aperture array at the Illgraben catchment (Switzerland, Canton Valais) between 2017 and 2021. The comparison between infrasonic signal features (maximum amplitude and peak frequency) and measured flow parameters (front velocity, maximum depth and discharge) showed that the infrasound radiation by debris flows linearly correlates with flow discharge and that the infrasonic peak frequency inversely scales with flow parameters, thus decreasing when flow velocity, depth or discharge increase. In addition, array analysis of infrasonic signals revealed that the infrasound by debris-flows at Illgraben appears to be dominated by clusters of coherent infrasonic detections generated near check dams located along the Illgraben channel.

These pieces of evidence suggest that debris flow infrasound is generated by turbulence-induced waves and oscillations developing at the free-surface of the flow, whose dimensions scale with the magnitude of the flow. As expected from fluid dynamics, these surface oscillations are primarily generated where the flow encounters significant channel irregularities, such as topographic steps, which consequently act as preferential sources of infrasound. To test the validity of our interpretation of infrasound source mechanisms within debris-flows we also compare infrasonic recordings of a water free overfall over a weir with video recordings of the flow, to investigate how infrasound correlates with the dynamic of the surface of the flow.
Investigating the influence of increased meltwater runoff on basal sliding in Northeast Greenland. 
Authors: Tabone Ilaria , Fürst Johannes , Mölg Thomas
Published: March 2022

One of the consequences of rising temperatures observed in Northeast Greenland during the last decades is the increase in surface melting. Meltwater runoff can reach the bed and influence the ice flow regime through changes in basal conditions. Yet, depending on the drainage system, meltwater increase can have opposite effects on basal sliding and there is no consensus yet on the mechanisms that govern this hydrological switch. Here we present some advances in understanding the effects of surface meltwater percolation on ice dynamics at the Northeast Greenland Ice Stream (NEGIS) by investigating surface melt-basal sliding interactions at various temporal scales. To this end, we make use of a fully coupled model approach, comprising the finite-element ice-flow model Elmer/Ice and the hydrological scheme GlaDS. The latter is capable of representing the water drainage at all levels of the ice column. High resolution daily surface mass balance reconstructions available for the years 2014-2018 and simulated by the surface energy balance model COSIPY are used to force the ice-flow model. After first sensitivity tests aiming to explore the parameters of the ice-flow-hydrology system model, a fully coupled simulation for the period 2014-2018 is performed. This advanced modelling framework allows us to tackle the response of the NEGIS ice flow to seasonal and multi-annual variations in surface melt through changes in the drainage system.
Partial tipping in a spatially heterogeneous world
Authors: Bastiaansen Robbin , Dijkstra Henk , von der Heydt Anna
Published: March 2022

Many climate subsystems are thought to be susceptible to tipping - and some might be close to a tipping point. The general belief and intuition, based on simple conceptual models of tipping elements, is that tipping leads to reorganization of the full (sub)system. Here, we explore tipping in conceptual, but spatially extended and spatially heterogenous models. These are extensions of conceptual models taken from all sorts of climate system components on multiple spatial scales. By analysis of the bifurcation structure of such systems, special stable equilibrium states are revealed: coexistence states with part of the spatial domain in one state, and part in another, with a spatial interface between these regions. These coexistence states critically depend on the size and the spatial heterogeneity of the (sub)system. In particular, in these systems a tipping point might lead to a partial tipping of the full (sub)system, in which only part of the spatial domain undergoes reorganization, limiting the impact of these events on the system's functioning.
CO2 injection and storage for geothermal power generation in hydrothermal reservoirs along the Red Sea of Western Saudi Arabia
Authors: Yalcin Bora , Ezekiel Justin , Mai P. Martin
Published: March 2022

As an alternative to water, CO2 can be used for heat mining from geothermal reservoirs, while also trapping most of the injected CO2 underground. In addition, supercritical CO2 has higher mobility and heat capacity than water, rendering CO2 capture, utilization and storage (CCUS) in geothermal reservoirs a very attractive option in a circular carbon economy. CCUS is also in line with Saudi Vision 2030, which includes the strategic framework to reduce Saudi Arabia’s dependence on hydrocarbons and diversify its economy. The western coast of Saudi Arabia, where the young and high-heat-flow Red Sea rift basins are located, are considered suitable for geothermal heat extraction and CO2 storage. In this study, we explore the potential of CCUS for geothermal power generation and CO2 storage in the hydrothermal reservoirs of Al Wajh basin located on the Red Sea coast.

Geological studies in Al Wajh basin report that the hot fluid bearing, thick, porous, siliciclastic formations, such as Al Wajh (formation’s top depth, TD= 3900 meters), Burqan (TD = 2880 m) and Jebel Kibrit (Umluj member with TD = 1930 m) are sealed by the overlying anhydrite (Kial) and salt formations (Mansiyah). We combine publicly available data with different resolution scales, such as satellite gravity, seismic sections and well-log information to build a 3D geologic model, which enables us to constrain the 3D gross rock volume and the Net-to-Gross ratio/distribution of the target hydrothermal reservoirs. A 3D temperature model shows that the average surface temperature in the region and the subsurface temperature gradient create formation fluid temperature of over 120o C at 3 km depth.

We conduct reservoir simulation of coupled transport of formation fluid, injected non-condensable gas (CO2) and heat in heterogeneous 3D reservoir model, using CMG STARS. We then estimate the geothermal energy extracting capacity and storage efficiency of CO2 in the prospective hydrothermal reservoirs in the Al Wajh basin. Our study provides the first semi-realistic reservoir model and simulation study in Saudi Arabia for combined CO2-based geothermal power generation and CO2 storage potential at a designated target site. The work-flow we propose is transferable to other suitable hydrothermal reservoirs in different locations in Saudi Arabia, thereby enabling CCUS technology implementation along the Red Sea.
A new Berriasian to Coniacian composite carbon isotope record from the Boreal Realm 
Authors: Bornemann André , Erbacher Jochen , Blumenberg Martin , Voigt Silke
Published: March 2022

High-amplitude shifts in sedimentary δ13C characterize the Cretaceous system and have been proven to be of great use for supraregional chemostratigraphic correlation. Here we present an upper Berriasian to lower Coniacian (c. 142 – 88 Ma) composite carbon isotope record based on 14 drill cores, two outcrops and almost 5000 samples. The total record comprises a composite thickness of about 1500 m. All cores and successions are located in the larger Hanover area, which represents the depocenter of the North German Lower Saxony Basin (LSB) in early to mid-Cretaceous times.

Boreal Lower Cretaceous sediments are predominantly represented by CaCO3-poor mud- and siltstones of up to 2000 m thickness in northern Germany, which become more carbonate-rich during the Albian-Cenomanian transition and even chalkier in the upper Cenomanian to Coniacian interval. A number of global carbon isotope key events including the Valanginian Weissert Event, the OAEs 1a, b and d (Aptian-Albian) as well as for the early Late Cretaceous the Mid-Cenomanian Event (MCE), the OAE 2 (Cenomanian-Turonian Boundary Event) and the Navigation Event, among others, have been identified allowing for a detailed comparison with Tethyan and other Boreal records. Thus, this new detailed chemostratigraphy provides a unique opportunity to potentially overcome many still existing Boreal–Tethyan correlation issues. The presented record can be considered to be almost complete, albeit a small gap in the early Albian cannot be ruled.
Large impact cratering during lunar magma ocean solidification
Authors: Miljkovic Katarina , Wieczorek Mark A. , Laneuville Matthieu , Nemchin Alexander , Bland Phil A. , Zuber Maria T.
Published: March 2022

The lunar cratering record is used to constrain the bombardment history of both the Earth and the Moon. However, it is suggested from different perspectives, including impact crater dating, asteroid dynamics, lunar samples, impact basin-forming simulations, and lunar evolution modelling, that the Moon could be missing evidence of its earliest cratering record. Here we report that impact basins formed during the lunar magma ocean solidification should have produced different crater morphologies in comparison to later epochs. A low viscosity layer, mimicking a melt layer, between the crust and mantle could cause the entire impact basin size range to be susceptible to immediate and extreme crustal relaxation forming almost unidentifiable topographic and crustal thickness signatures. Lunar basins formed while the lunar magma ocean was still solidifying may escape detection, which is agreeing with studies that suggest a higher impact flux than previously thought in the earliest epoch of Earth-Moon evolution.
The impact of precise inter-satellite ranges on relative precise orbit determination in a smart CubeSats constellation
Authors: Allahvirdi-Zadeh Amir , El-Mowafy Ahmed
Published: March 2022

The use of CubeSats is expanding in space and earth science applications due to the low costs of building and the possibility of launching them in a large low-earth orbits (LEO) constellation. Such constellation can serve as an augmentation system for positioning, navigation and timing. However, real-time precise orbit determination (POD) is still one of the challenges for this application. Real-time reduced-dynamic POD requires more processing capability than what is available in current CubeSats, and the kinematic POD highly depends on the number and the quality of the signals from Global Navigation Satellite Systems (GNSS). In this study, an approach is proposed to increase the orbital accuracy by implementing the precise inter-satellite ranges in the Kinematic POD. The precise orbits of a set of CubeSats from the Spire Global constellation that are determined using the reduced-dynamic POD is to be used to generate the precise inter-satellite ranges. These ranges vary from hundreds to thousands of kilometres and are constrained in the relative kinematic POD between the tested CubeSats. The results, which depend on the length of the inter-satellite ranges, show the improvement of the orbital accuracy in all directions. An initial architecture for implementing such a method in a smart CubeSats constellation is proposed and the limitations and remedies are discussed.
Arbuscular mycorrhiza promotes the clean production of subtropical orchards
Authors: Liu Hongguang
Published: March 2022

The intensive management of orchards is posing substantial pressure to the surrounding environments, threatening the fruit quality and sustainable development of fruit industry. Arbuscular mycorrhiza (AM) is ubiquitous in soil established with arbuscular mycorrhizal fungi colonizing roots of host plants. AM connects the roots, bacteria and soil, enhancing the interactions between plants and soil microbiome, augmenting the nutrient uptake of plants, improving fitness in facing abiotic and biotic stresses, and strengthening the soil structure and function. Thus, AM is considered as an important grasp to improve the clean production, and an alternative for the shift from intensive to organic management in orchards. Our study showed that the disappearance or reduction of AM fungi community, in accordance with strong soil erosion and the losses of phosphorus. The practices, such as sod culture in orchards or inoculating with AM fungi, is beneficial to the recovery of AM fungi community. More suitable measures aiming at optimize the AM fungi community are being developed and extended in subtropical orchards. Collectively, the regulation of AM fungi community can be a significant way to improve the degree of clean productions of subtropical orchards.
Inversion of Hydraulic Tomography Data from the Grimsel Test Site with a Discrete Fracture Network Model
Authors: Ringel Lisa Maria , Jalali Mohammadreza , Bayer Peter
Published: March 2022

This study aims at the stochastic characterization of fractured rocks with a low-permeability matrix based on transient data from hydraulic tomography experiments. In such rocks, fractures function as main flowpaths. Therefore, adequate insight about distribution and properties of fractures is essential for many applications such as groundwater remediation, constructing nuclear waste repositories or developing enhanced geothermal systems. At the Grimsel test site in Switzerland, multiple hydraulic tests have been conducted to investigate the hydraulic properties and structure of the fracture network between two shear zones. We present results from combined stochastic inversion of these tests to infer the fracture network of the studied crystalline rock formation.

Data from geological mapping at Grimsel and the hydraulic tomography experiments that were undertaken as part of in-situ stimulation and circulation experiments provide the prior knowledge for the model inversion. This information is used for the setting-up of a site-specific conceptual model, to define the boundary and initial conditions of the groundwater flow model, and for the configuration of the inversion problem. The pressure signals we apply for the inversion stem from cross-borehole constant rate injection tests recorded at different depths, whereby the different intervals are isolated by packer systems.

In the forward model, the fractures are represented explicitly as three-dimensional (3D) discrete fracture network (DFN). The geometric and hydraulic properties of the DFN are described by the Bayesian equation. The properties are inferred by sampling iteratively from the posterior density function according to the reversible jump Markov chain Monte Carlo sampling strategy. The goal of this inversion is providing DFN realizations that minimize the error between the simulated and observed pressure signals and that meet the prior information. During the course of the inversion, the number of fractures is iteratively adjusted by adding or deleting a fracture. Furthermore, the parameters of the DFN are adapted by moving a fracture and by changing the fracture length or hydraulic properties. Thereby, the algorithm switches between updates that change the number of parameters and updates that keep the number of parameters but adjust their value. The inversion results reveal the main structural and hydraulic characteristics of the DFN, the preferential flowpaths, and the uncertainty of the estimated model parameters.
How to determine the anthropogenic signal at less settled spatially bounded archaeological sites?
Authors: Janovský Martin , Danielisová Alžběta , Horák Jan , Strouhalová Barbora , Bursák Daniel
Published: March 2022

Our research on spatially bounded Iron Age enclosure of the Viereckschanze type in southern Bohemia made it possible to distinguish the anthropogenic influence of the Iron Age from modern human activities. We collected over 456 samples from 200 cores to a depth of up to one metre. Samples were measured using pXRF to determine the content of the following elements: Al, Si, P, K, Ca, Ti, Mn, Fe, Cu, Zn, As, Rb, Sr, Zr, Pb, and LE – ‘light elements’). Subsequent isometric log-transformation of ppm elemental contents and PCA allowed to distinguish the prehistoric anthropogenic influence from the current modern one. The result of the analysis is as follows: 1) the P signal typical for archaeological settlements was found mainly outside of the enclosure; 2) the conventional anthropogenic signal from the inside of the enclosure was only represented by Mn; 3) other elements related to possible anthropogenic activities were revealed only after applying statistical analysis (As, Pb, Zn, Cu); 4) the unusual manifestation of Si and Ti was connected to the archaeological contexts. The combination of these results (Cu, Zn, Pb) and magnetic measurements revealed places of metallurgical activity inside Viereckschanze. It is certain that the site was not only a place of residential activity, but also of production activity. Viereckschanze was only occupied for a short period of time.

The presented abstract is adapted from the article published in Catena in 2022.

 

Acknowledgements:

This work was supported by the Czech Science Foundation [Project: Mobility of materials and life cycles of artefacts: archaeometry of metals and glass of the La Tène and early Roman period; project number: 18-20096S]. M.J. was supported by project “Geochemical insight into non-destructive archaeological research” (LTC19016) of subprogram INTER‐COST (LTC19) of program INTEREXCELLENCE by Ministry of Education, Youth and Sport of the Czech Republic.
Analysis of global trends of total column water vapour from multiple years of OMI observations
Authors: Borger Christian , Beirle Steffen , Wagner Thomas
Published: March 2022

Atmospheric water plays a key role for the Earth’s energy budget and temperature distribution via radiative effects (clouds and vapour) and latent heat transport. Thus, the distribution and transport of water vapour are closely linked to atmospheric dynamics on different spatiotemporal scales. In this context, global monitoring of the water vapour distribution is essential for numerical weather prediction, climate modelling, and a better understanding of climate feedbacks.

Total column water vapour (TCWV), or integrated water vapour, can be retrieved from satellite spectra in the visible “blue” spectral range (430-450nm) using Differential Optical Absorption Spectroscopy (DOAS). The UV-vis spectral range offers several advantages for monitoring the global water vapour distribution: for instance, it allows for accurate, straightforward and consistent retrievals over ocean and land surface even under partly-cloudy conditions.

To investigate changes in the TCWV distribution from space, the Ozone Monitoring Instrument (OMI) on board NASA’s Aura satellite is particularly promising as it provides long-term measurements (late 2004-ongoing) with daily global coverage.

Here, we present a global analysis of trends of total column water vapour retrieved from multiple years of OMI observations (2005-2021) and put our results in context to TCWV trends from other climate data records (e.g. reanalysis models or satellite measurements). Additionally, we investigate if the assumption of constant relative humidity over climatological time periods is fulfilled.

Furthermore, we demonstrate that it is possible to infer changes in the global atmospheric circulation directly from the global TCWV distribution: More precisely, we show that trends in changes in the location of the Hadley cell as well as its poleward expansion can be determined from the latitudinal TCWV distribution using a simple, straightforward and robust methodology.
Developing low-likelihood climate storylines for extreme precipitation using ensemble boosting
Authors: Gessner Claudia , Fischer Erich M. , Beyerle Urs , Knutti Reto
Published: March 2022

Heavy precipitation events as the one in western Germany and the Benelux countries in July 2021 destroy the local infrastructure and numerous fatalities. Due to the lack of long homogenous climate data and methodological framework, it is uncertain how intense precipitation extremes could get. We address these questions by developing storylines of the rarest precipitation events. We here generate large samples of reinitialized heavy rainfall events starting from the most extreme events in an initial condition large ensemble for the near future, carried out with CESM2. In an approach referred to as ensemble boosting, we first reinitialize the most extreme 3-day precipitation events to estimate how anomalous they could get. We find that the most extreme precipitation events can be substantially exceeded in the boosted ensembles for different regions across the world. Second, we evaluate whether the model can reproduce analogues of the precipitation event in July 2021 and re-initialize these events to analyze how this event type could have evolved and whether it could have become even more intense. In doing so, the ensemble boosting method provides storylines of heavy rainfall development beyond the observational record, which can be used to generate worst-case scenarios and stress test the socioeconomic system.
On the ability of CMIP6 OMIP models to simulate the seasonalcycle of the ocean mixed layer depth in the central Arctic Ocean
Authors: Allende Sofia , Fichefet Thierry , Goosse Hugues
Published: March 2022

In this study, we assess the ability of the ocean-sea ice general circulation models that participated in the CMIP6 Ocean Model Intercomparison Project (OMIP) to simulate the seasonal cycle of the ocean mixed layer depth in the area of the Arctic Ocean covered by multiyear sea ice. During summertime, all models understimate the mixed layer depth by about 20 m compared to the MIMOC (Monthly Isopycnal/Mixed layer Ocean Climatology) observational data. The origin of this systematic bias is unclear. In fall and winter, differences of several tens of meters are noticed between the models themselves and between the models and the observational data. Some models generate too deep mixed layers, while others produce too shallow mixed layers. Since the mixed layer deepening in ice-covered regions during these seasons is largely controlled by the brine rejection associated with ice growth, the discrepancies between models might be related to differences in the modelled sea ice mass balance. However, a detailed model comparison reveals that this is not the case, all models simulating more or less the same sea ice mass balance and thus salt flux into the ocean during sea ice freezing. By applying to model outputs the analytical model developed by Martinson (1990), that allows in particular to determine the main processes responsable for maintaining stablility in polar oceans, it is finally found that most of the disagreement between models can be explained by the accuracy with which the Arctic halocline is reproduced by those models. This feature is simulated generally poorly and quite differently from one model to another, and models with less stratified halocline generally lead to deeper mixed layers. It now remains to identify the model deficiencies responsible for this situation.
Energy exchange at the micro-scale during the operation of a ventilator for frost protection
Authors: Boekee Judith , Dai Yi , Schilperoort Bart , van de Wiel Bas , ten Veldhuis Marie-Claire
Published: March 2022

A late frost in spring can cause extensive damage and substantial economic losses for agriculture around the world. To mitigate damage, fruit farmers take active measures to raise plant and air temperatures, such as ventilators that mix warm overlying air down to the vegetation. However, up to this point studies on ventilator efficiency have focused on air temperatures. Plant temperatures during ventilator operation remain unknown, while critical for the actual degree of frost damage. With Distributed Temperature Sensing we measured a grid of in-canopy air temperatures in a Dutch pear orchard and thermocouples were installed to determine the temperatures of plant leaves and flower buds. It turns out that before or without ventilator operation, the leaves are cooler than the surrounding air by up to 2 ⁰C. Here we show that over the rotation cycle of a ventilator the temperature difference between plant and air is variable and can be divided into three phases. During the first phase warm air is mixed into the canopy by the ventilator. Air temperatures rise faster than leaf temperatures due to the leaves’ heat capacity and isolating leaf boundary layer. The extent of the temperature rise depends on the distance to the ventilator. Further from the ventilator, the canopy reduces the jet speed and thus vertical mixing. At the peak of the jet, phase II, the high wind speeds break down the leaf boundary layer and enhance convective energy exchange. When the plant temperature approaches air temperature, the convective warming of the leaves stops, and radiative cooling becomes the dominant process. At phase III, after the passage of the jet, the air stabilizes and the leaves cool radiatively until a new equilibrium is reached. Our results demonstrate how leaf-air heat exchange within the canopy differs under varying turbulence conditions. For maximum crop protection and optimal employment of the ventilator both wind speed and air temperature in the canopy should be taken into consideration. Therefore, we expect that optimal settings may vary throughout the growing season as canopy density and the corresponding wind reduction change.
Megaflap formation and Damage recording: the case of the Cotiella Megaflap, South-Central Pyrenees.
Authors: Lartigau Marine , Callot Jean-Paul , Aubourg Charles , Kergaravat Charlie
Published: March 2022

Salt tectonics is responsible for typical structures associated with salt structures margins development: (i) minibasin subsidence, (ii) basin edge backfolding of basin margins, forming plurikilometric steep or overturned structures along the salt structures or their equivalent welds, called megahooks and megaflaps and (iii) smaller-scale halokinetic drape folding and composite halokinetic sequences (CHS). Mega-halokinetic structures like the megaflaps are of particular interest to us as they have been recently defined and their kinematics are poorly understood compared to those of CHS. They develop either during halokinetic drape folding, or during contractional squeezing of the diapirs or during some combination of both processes. It seems megaflaps form early in the salt reliefs development as opposed to more mature structures allowing the CHS development. Because of their geometry, megaflaps have also implications for reservoirs geometries and fluid pressures distribution, critical for successful exploration or potential storage. Megaflaps seem to have the same behaviour as detachment folds and could present same kinematics and deformations. Characterizing the multi-scale damage records, using fracturation network and matrix damage analyses, may allow us to reconstruct the megaflaps formation dynamics and to establish relationships between reservoir properties and structural evolution.

In the Cotiella Basin, recent studies have shown the role of salt tectonics associated with gravity in the creation of various minibasins during the post-rift system between the Cenomanian and the Santonian. The Cotiella minibasin s.s. presents a megaflap with vertical to completely overturned layers. The calcarenites composing this megaflap present numerous joints, veins and stylolites. The first observations and analyses show several stages of deformation, from Layer Parallel Shortening (LPS) to Late Stage Fold Tightening (LSFT) as observed in the folds. Moreover, preliminary results of matrix damage, using AMS, also indicate a record of LPS and even late deformation, LSFT, in the rocks. A detailed scenario of the damage acquisition chronology, from the multi-scale damage, is under contruction to understand the formation of this megaflap. We will then be able to compare the damage, the type of megaflap and the causal relationships such as geodynamic context and lithology with others such as the Sivas megaflap (Turkey).
Multidecadal Delay Between Deglaciation and Formation of a Proglacial Lake Sediment Record
Authors: Piret Loic , bertrand Sebastien , Torrejón Fernando
Published: March 2022

Proglacial lake sediments are widely recognised as accurate and high-resolution archives of climate and glacier variability. Sediments deposited in proglacial lakes are frequently varved, which offers the possibility to generate precisely-dated records, and their basal ages are often used to constrain deglaciation histories. It is often assumed that lake sedimentation starts immediately after deglaciation. With this in mind, we studied the onset of lake sedimentation in a recently deglaciated lake (Calluqueo Lake, Chilean Patagonia) to investigate the possible delay between proglacial lake formation and establishment of a continuous sediment record. Calluqueo Lake is a 3.5 km long lake composed of a large 220 m deep proximal basin, separated from a smaller 50 m deep distal basin by a 40 m deep sill. The lake is bordered by steep lateral moraines that contain large boulders. Aerial images and historical data show that Calluqueo Glacier entirely covered the lake basin until 1941. Since then, it rapidly receded until it became land-based in 1985. Side Scan sonar images and grab sampling shows that the sediment cover is limited to the small distal basin, which was entirely deglaciated by 1978. By comparison, no sediment was found in the deepest proximal basin although it has been ice free for at least three decades. Varve counting of sediments deposited in the distal basin shows that the stratigraphic record starts in 1996 ± 4 CE, i.e., that the first 20 – 50 years of the glacier’s retreat are not represented in the sediments of Calluqueo Lake. We hypothesize that the fine-grained sediments that are discharged into the lake immediately after its formation first start accumulating between the large boulders that compose the ablation moraine on the lake floor. The continuous stratigraphic record only starts forming after the coarse moraine deposits are buried under fine-grained particles. Our results have important implications for the use of proglacial lake sediments in paleoclimate and paleoenvironmental research. They suggest that proglacial lake sediment records lack the first 20 – 50 years of sedimentation. Although this delay may be negligible for reconstructions of deglaciation histories based on basal radiocarbon ages, it becomes significant for the use of lake sediment records from recently deglaciated environments.
Detecting Climate Fingerprints in Southern Ocean Carbon Using a Global Ocean Biogeochemical Model and Observations
Authors: Wright Rebecca , Le Quéré Corinne , Willis David , Bakker Dorothee , Mayot Nicolas
Published: March 2022

The Southern Ocean (SO) plays an important role in the uptake, transport and storage of carbon by the global oceans. These properties are dominated by the rise in anthropogenic CO2 in the atmosphere, but they are modulated by climate variability and climate change. Here we explore the effect of climate variability and climate change in the SO using a combination of modelling and observations to identify climate fingerprints in dissolved inorganic carbon (DIC). We conduct an ensemble of hindcast model simulations using the NEMO-PlankTOM12 global ocean biogeochemical model. We use the model to isolate the changes in DIC due to anthropogenic CO2 alone and the changes due to climatic drivers (both climate variability and climate change) and determine their relative roles in the emerging total DIC trends and patterns. We analyse the DIC climate fingerprint since 1995, across spatial scales in the SO, and check the extent to which they are detectable in the GLODAPv2.2020 observations. Model results were subsampled to the observations to directly compare the climate fingerprints. Results show that in the surface ocean, both anthropogenic CO2 and climatic drivers act to increase DIC concentration, with the influence of anthropogenic CO2 dominating at lower latitudes (<55°S) and the influence of climatic drivers dominating at higher latitudes (>55°S). This pattern is present in all basins. In the subsurface ocean, climatic drivers act to decrease DIC concentration, opposing the influence of anthropogenic CO2, with a stronger decrease at lower latitudes (<50°S). These patterns resulted in a climate fingerprint specific to SO change and were detectable in the observations. However, the model underestimates the surface DIC increase and the spatial and depth variability of the subsurface DIC decrease. We use the model to directly attribute the climate fingerprint to various climate drivers and discuss timescales for unambiguous detectability of the fingerprint in observations.
West African monsoon precipitation impacted by the South Eastern Atlantic biomass burning aerosol outflow
Authors: solmon fabien , elguindi nellie , mallet marc , flamant cyrille , formenti paola
Published: March 2022

The West African Monsoon (WAM) is a complex system depending on global climate influences and multiple regional environmental factors. Central and Southern African biomass-burning (SABB) aerosols have been shown to perturb WAM during episodic northward inter-hemispheric transport events, but a possible dynamical connection between the core of the SABB aerosol outflow and the WAM system remains unexplored. Through regional climate modeling experiments, we show that SABB aerosols can indeed impact WAM dynamics via two competitive regional scale and inter-hemispheric dynamical feedbacks originating from (i) enhanced diabatic heating occurring in the Southeastern Atlantic low-cloud deck region, and (ii) aerosol and cloud-induced sea surface temperature cooling. These mechanisms, related to aerosol direct, semi-direct, and indirect effects, are shown to have different seasonal timings, resulting in a reduction of June to September WAM precipitation, while possibly enhancing late-season rainfall in WAM coastal areas.
Modelling water fluxes in a soil profile of a degraded peatland site
Authors: Davies Mariel , Dietrich Ottfried , Merz Christoph
Published: March 2022

Reducing greenhouse gas emissions from degraded, agriculturally used peatlands is a vital contribution to meeting the German climate protection targets by 2050. It requires an understanding their closely coupled hydraulic and geochemical processes, which is the basis of sustainable land and water management on these sites. Hydraulic modelling of the fluxes in a soil profile was done to characterise the hydraulic state of a degraded peatland site with spatially and temporally high resolution. The basis of the model were measurements from groundwater lysimeters in a site with three horizons in Spreewald wetland, Germany. The model was implemented in the one-dimensional hydraulic modelling software Hydrus-1D. The first step was the determination of initial soil hydraulic properties using soil physical properties and the ROSETTA tool based on pedotransfer functions, which is integrated in Hydrus-1D. Two model variants were set up that differed in their lower boundary condition – either the measured pressure head (representing groundwater level) or the measured flux at the lower boundary of the lysimeter. The modelled volumetric water contents, pressure heads and groundwater table (variant 1) or fluxes at lower boundary (variant 2) were validated with the measured lysimeter data. In a second step, the soil hydraulic parameters were inversely optimised based on measured time series data, for both variants. To further improve the model results, dual porosity type flow was implemented in the upper two horizons. The different steps were able to continuously improve the model. The choice of lower boundary condition had an effect on the quality of the model results: The use of groundwater table as lower boundary condition improved the modelled volumetric water contents and pressure heads, but yielded deviating fluxes at the lower boundary in comparison to the measurements. The application of flux as a lower boundary condition produced deviations in the modelled groundwater table, the water contents and the pressure heads, especially after heavy rainfall events. The integration of preferential flow (dual porosity) into the model improved the vadose zone pressure head and water content results significantly.
Sample Association by using Anomalous Concentration Episodes and Decay-Consistent Isotopic Ratios at IMS Radionuclide Stations
Authors: Kijima Yuichi , Kalinowski Martin , Liu Boxue , Kuśmierczyk-Michulec Jolanta , Schoemaker Robin , Tipka Anne
Published: March 2022

For enhancement of the International Data Centre (IDC) products such as the Standard Screened Radionuclide Event Bulletin (SSREB), there is a need to associate the detections of CTBT relevant isotopes in samples at International Monitoring System (IMS) radionuclide stations with the same release to characterize its source for the purpose of nuclear explosion monitoring. Episodes of anomalous concentrations at the stations are the best first guess for being related to the same event. For multiple isotope observations, the consistency of their isotopic ratios in subsequent samples with radioactive decay is another plausible hint at coming from the same source. Moreover, atmospheric transport modelling (ATM) will help to get further evidence and gain confidence in sample associations by identifying the air masses that link the release to multiple samples. We focused on the basic approach as well as the criteria for automatic sample association for the SSREB.
Distinct short term response of C exchange to topsoil dilution and N-fertilization form at erosion affected arable land
Authors: Vaidya Shrijana , Schmidt Marten , Kramp Katja , Rakowski Peter , Bonk Nobert , Buddrus Robert , Verch Gernot , Sommer Michael , Augustin Jürgen , Hoffmann Mathias
Published: March 2022

On arable land, C dynamics and storage are significantly influenced by tillage and N fertilization. Therefore, new practices such as the combination of topsoil dilution (e.g., through fractional deep tillage) and organic N fertilization may not only ameliorate soil's physical and chemical properties and promote root development but might also enhance soil organic carbon (ΔSOC) stocks. However, the impact of these practices depends on site-specific conditions as agricultural landscapes are often characterized by distinct small-scale soil heterogeneities. To upscale and evaluate the effects or benefits of these new farming practices, accurate and precise information on the complex spatio-temporal C flux pattern and their drivers are thus needed.

To investigate the impact of topsoil dilution and organic N fertilization on SOC storage, we performed a study in the strongly erosion affected arable landscape of NE Germany (Uckermark region, 53° 23' N, 13° 47' E; ~50-60 m a.s.l). The study area consisted of 36 measurement plots, of which each 12 covered one out of three erosion induced soil types; Calcic Luvisol (non-eroded), Nudiargic Luvisol (strongly eroded) and Calcaric Regosol (extremely eroded). During July 2020, a two factorial experimental design was established (topsoil dilution vs no topsoil dilution and mineral N fertilization vs organic N fertilization) through implementing topsoil dilution and organic N fertilization on three replicates of each of the three measured soil types. Topsoil dilution was achieved by removing the upper 6 cm of the topsoil layer adding/mixing equivalent weight of subsoil into it.

Subsequently, relevant C fluxes, especially the CO2 exchange, were measured using a new robotic chamber system. C in plant biomass was measured by weekly biomass sampling on a nearby reference site and related to plot measurements of CO2 through NDVI (normalized difference vegetation index) and RVI (ratio vegetation index) measurements. Here, we present our first results on the effect of soil type, topsoil dilution, and N-fertilization form on CO2 and C exchange of winter rye. Our results show that there are not only differences between the distinct soil types but also differences between the non-diluted and diluted topsoil treatments. The latter show lower cumulated ecosystem respiration and gross primary productivity, as well as a lower RVI/NDVI  and above-ground biomass production, compared to the non-diluted soil. No substantial difference, however, was detected in the case of net ecosystem exchange. As a result, net ecosystem carbon balance was lower for diluted topsoil compared to the non diluted treatments.
Bromine, Iodine and Mercury on the East Antarctic plateau: preliminary results from sampling along a traverse. 
Authors: Celli Giuditta , Cairns Warren R.L. , Savarino Joel , Stenni Barbara , Frezzotti Massimo , Maffezzoli Niccolò , Turetta Clara , Scarchilli Claudio , Delmonte Barbara , Traversi Rita , Spolaor Andrea
Published: March 2022

Sunlit snow is highly photochemically active and plays a key role in the exchange of gas phase species between the cryosphere and the atmosphere. Bromine (Br), Iodine (I) and Mercury (Hg) can be photoactivated by the UV radiation and, in certain circumstances, released from the snowpack into the atmosphere. Mercury is a heavy metal with a known toxicity present in the environment in several different chemical forms. Once present in the snowpack, Hg is very labile and, thanks to the UV light, it can be reduced back to elemental Hg (Hg(0)) and undergo dynamic exchange with the atmosphere. Similar to mercury, iodine can undergo photochemical activation in surface snow resulting in its presence in the surrounding atmosphere where it plays a crucial role in new particle formation. Bromine  has a central role in the mercury cycle in polar regions (through the Atmospheric mercury depletion events) as well as contributing to the tropospheric ozone cycle in the polar region causing the so-called Ozone depletion events. However, compared to Iodine and Mercury, it seems to be more stable after deposition into the snow pack. 

Here we present measurements of bromine, iodine and mercury performed by ICP-MS, on snow pit and shallow core samples taken over a 2100 km traverse in East Antarctica from the coast to the interior (Talos Dome – Dome C traverse 2016 and East Antarctic International Ice Sheet Traverse, EAIIST 2019). The shallow core and the snow pit samples at each site are estimated to cover about 10 to 20 years of snow accumulation, giving us a deposition record from approximately the late 90s, to around the early 21st century. The concentrations determined in different  sampling sites show a rather clear decrease trend from the coast with the minima as we approach the inner part of the Antarctic plateau. In addition, the analysis of surface and bulk samples from EAIIST show a decrease of concentrations toward the inland except for the sites characterised by a strong snow metamorphosis caused mainly by the wind friction. In almost all the sampling sites of the EAIIST traverse the concentrations of Br, I and Hg increase with sample depth, possibly due to snowpack photochemical activation in the upper part of the snowpack. Future studies are planned to  investigate the possible link between the determined concentration profile and the variation of the solar radiation reaching the Antarctic Plateau during spring caused by the ozone hole formation. 
The response of benthic foraminifera to the late Miocene-early Pliocene Biogenic Bloom: the record from Southeast Atlantic Ocean (ODP Site 1085)
Authors: Gastaldello Maria Elena , Agnini Claudia , Westerhold Thomas , Dallanave Edoardo , Alegret Laia
Published: March 2022

The late Miocene-early Pliocene Biogenic Bloom was a significant event defined by the anomalously high marine biological productivity documented in the Indian, Pacific, and Atlantic Oceans; but its causes and consequences at different paleogeographical settings are not yet fully understood. Previous records from Ocean Drilling Program (ODP) Site 1085 (Cape Basin, Southeast Atlantic Ocean) indicate enhanced biological productivity between 7 and 4 Ma, as supported by increased linear sedimentation rates, benthic foraminiferal accumulation rates, and increased total organic carbon mass accumulation rates (Diester-Haass et al., 2002; 2004). To look into the paleoenvironmental consequences of the Biogenic Bloom, we investigated the benthic foraminiferal turnover at this site. Results were integrated with an age model based on a bio-astrocyclostratigraphic tuning and low-resolution carbon and oxygen stable isotope records on benthic foraminifera (i.e. Cibicidoides mundulus) across an interval spanning from the Tortonian (late Miocene) to the Zanclean (early Pliocene). Quantitative analyses of the assemblages and statistical analyses point to increased food supply to the seafloor. The proliferation of phytodetritus exploiting taxa such as Alabamina weddellensis and Epistominella exigua point to an episodic nutrient supply related to seasonal phytoplankton blooms during the Biogenic Bloom.

Reference

Diester-Haass, L., Meyers, P. A., & Vidal, L. (2002). The late Miocene onset of high productivity in the Benguela Current upwelling system as part of a global pattern. Marine Geology, 180(1-4), 87-103.

Diester-Haass, L., Meyers, P. A., & Bickert, T. (2004). Carbonate crash and biogenic bloom in the late Miocene: Evidence from ODP Sites 1085, 1086, and 1087 in the Cape Basin, southeast Atlantic Ocean. Paleoceanography, 19(1).

Acknowledgements

University of Padova DOR grant, CARIPARO Foundation Ph.D. scholarship.

Spanish Ministry of Economy and Competitiveness and FEDER funds (PID2019-105537RB-I00).