bluuebunny/crossref_metadata_2025 huggingface dataset:
Imprint of landscape dynamics in the luminescence signal of fluvial sediments (Rangitikei River, NZ)
Authors: Guyez Anne , Bonnet Stephane , Reimann Tony , Carretier Sébastien , Wallinga Jakob
Published: March 2021

Enlightenment of sediments pathways and storage patterns within river systems is critical to apprehend sediment transfer at the Earth’s surface and landscape response to tectonics and climate. Because direct tracing methods (painted, fluorescent or magnetic sediments) are of limited use in terms of their analytical resolution in time and space, alternative physico-chemical methods suitable for larger spatial-temporal scales have been developed (e.g. cosmogenic isotope, detrital thermochronology, isotopic geochemistry, etc). The study of the natural luminescence of sediment particles is emerging for this purpose and seems promising for providing new information complementary to existing methods. This method is based on the quartz/feldspar grains ability to store energy while buried below the Earth’s surface and to emit lumen with light exposure. Some recent studies have used this property to solve geomorphological questions regarding particle fluxes in soil or fluvial systems (Reimann et al., 2017; Sawakuchi et al., 2018) and to quantify rock exhumation (e.g. Herman et al., 2010). Here, we present an experimental testing of an innovative single-grain luminescence-based approach on feldspars. Focusing alongstream the Rangitikei River (RR), New Zealand, we carried out analysis on both modern sediment and Holocene terraces deposits.

We based our analysis on two complementarians proxies, the paleodose estimated using the bootstrapped minimum age model (Cunningham and Wallinga, 2012) and the percentage of grains eroded from bedrock and re-deposited in the river without signal resetting, i.e. saturated grains. We document changes in the luminescence signature of fluvial sediments while the RR evolves in response to uplift and climate change; from a late Pleistocene-early Holocene braided system to a Holocene incising canyon that subsequently widen.  This allows us to appraise temporal changes in the alongstream contribution of canyon flanks landsides to sediment supply to the river. Overall, we show that distinct landscape dynamics gives distinct luminescence signatures.
Improved soil moisture estimation with Sentinel-1 for arable land at the field scale
Authors: Beale John , Waine Toby , Corstanje Ron , Evans Jonathan
Published: March 2021

The change detection method of multi-temporal analysis is often used to estimate surface soil moisture from Sentinel-1 SAR data. The underlying assumptions that vegetation cover and soil surface roughness vary significantly more slowly with time than soil moisture are problematic in areas under cultivation, which are characterised by seasonal cycles of rapid crop growth, senescence, harvesting and tillage. The issue becomes more acute when data is processed at the field scale. Other areas, where the vegetation cover is persistently high, also exhibit poor sensitivity of SAR backscatter to soil moisture. In general, the mean absolute error appears to be related to the relative fractions of photosynthetically active and inactive vegetation, and bare soil. Optical indices derived from Sentinel-2 data may be used with spectral unmixing to estimate these fractions as time series at field scale. Combined with knowledge of land use, confidence levels may be assigned to each field. The soil moisture may then be estimated by two dimensional interpolation using inverse distance squared weighting across a range of neighbouring fields within a local zone.  During the peak growing season, the mean absolute error in the soil moisture estimate for wheat fields is significantly reduced, in one example from around 20% volumetric water content to less than 5%. This will benefit users of such products in agriculture, for example, in determining actual soil moisture deficit in the growing season.
Soil salinity monitoring and detection of obstructed drainage pipes in the B-XII irrigation district (SW Spain) using electromagnetic induction sensing and inversion. 
Authors: Ramos Mario , Farzamian Mohhamad , Gómez José Luis , González Alfonso , Salvatierra Benito , Martínez Gonzalo , Vanderlinden Karl
Published: March 2021

Inversion of electromagnetic induction (EMI) signals is increasingly used for monitoring soil salinity in irrigated fields. In the B-XII irrigation district (SW Spain) the build-up of high salt concentrations in the topsoil is often related with a deficient performance of the underlying drainage system resulting in higher-than-average soil moisture conditions and salinization. This work aims at using EMI sensing and inversion to identify and localize problems (e.g. obstruction) with the drainage system in a 12.5 ha irrigated field in the B-XII irrigation district. The identified salinity hotspots in the EMI images are further validated using remotely sensed NDVI data and detailed information obtained during the cleaning of the drainage system, in addition to hard soil data. This study shows that EMI sensing and inversion can pinpoint problems with the drainage system that result in salinity hotspots and identify areas where the drainage system should be cleaned or substituted.

 

This work is funded by the Spanish State Agency for Research through grants PID2019-104136RR-C21 and PID2019-104136RR-C22 and by IFAPA/FEDER through grant AVA2019.018.
Source reconstruction of the 1969 Sulawesi, Indonesia earthquake and tsunami
Authors: Pranantyo Ignatius Ryan , Cipta Athanasius , Shiddiqi Hasbi , Heidarzadeh Mohammad
Published: March 2021

An M7.0 earthquake followed by moderate tsunami destructed Majene region, western Sulawesi on 23 February 1969. This event claimed at least 64 lives and caused severe damage to infrastructure. In this study, we reconstructed the earthquake and tsunami source of this event by optimising macroseismic and tsunami dataset reported as well as analysed the earthquake focal mechanism. We estimated that the maximum intensity of the earthquake was VIII (in Modified Mercalli Intensity). From the first motion polarity analysis, the earthquake had a thrust mechanism which was plausibly from the Makassar Thrust. Further, deterministic ground motion modelling successfully fits the intensity data. However, thrust earthquake from the Makassar Thrust was unable to reconstruct 4 m tsunami height observed at Pelattoang. The estimated ratio between maximum tsunami run-up height and lateral distribution distance (I2) from the dataset indicates that the tsunami was generated by a local coastal landslide.

(This study is funded by the Royal Society (UK) grant number CHL/R1/180173)
Forecasting annual maximum water level for Negro River at Manaus
Authors: Chevuturi Amulya , Klingaman Nicholas P. , Woolnough Steven J. , Rudorff Conrado M. , Coelho Caio A. S. , Schongart Jochen
Published: March 2021

Variations in water levels of the Negro River, that flows through the Port of Manaus, can cause considerable regional environmental and socio-economic losses. It is therefore critical to advance predictions for water levels, especially flood levels, to provide more effective and earlier warnings to safeguard lives and livelihoods. Variations in water levels in free-flowing river systems, like the Negro follow large-scale precipitation anomalies, which offers an opportunity to predict maximum water levels using observed antecedent rainfall. This study aims to improve the performance and extend the lead time of statistical forecasts for annual maximum water level of the Negro River at Manaus, relative to operational forecasts. Multiple linear regression methods are applied to develop forecast models, that can be issued in March, February and January, with the best possible combinations potential predictors: observed antecedent catchment rainfall and water levels, large-scale modes of climate variability and the linear trend in water levels. Our statistical models gain one month of lead time against existing models, but are only moderately better than existing models at similar lead time. Using European Centre for Medium-Range Weather Forecasts (ECMWF) seasonal reforecast data with our statistical models, further gains an additional month of lead time of skilful performance. Our models lose performance at longer lead times, as expected. Our forecast models can issue skilful operational forecasts in March or earlier and have been successfully tested for operational forecast of 2020. This method can be applied to develop statistical models for annual maximum water level over other free-flowing rivers in the Amazon basin with intact catchments and historical water level record.
Stratospheric modulation of cold air outbreaks and winter storms in the North Atlantic region and impacts on predictability
Authors: Afargan-Gerstman Hilla , Polkova Iuliia , Papritz Lukas , Ruggieri Paolo , King Martin P. , Athanasiadis Panos , Baehr Johanna , Wulff Ole , Sprenger Michael , Domeisen Daniela I.V.
Published: March 2021

Variability of the stratospheric polar vortex has the potential to influence surface weather by imposing negative North Atlantic Oscillation (NAO) conditions, associated with cold air outbreaks in the Arctic and a southward shift of the extratropical storm track. In particular, the likelihood of cold temperature extremes over the ocean, known as marine cold air outbreaks (MCAOs), have been associated with a range of hazardous conditions, including strong surface winds and the occurrence of extreme cyclones known as Polar Lows (PLs), posing risks for Arctic marine activity and infrastructure. Likewise, winter storms can lead to high damage potential in the extratropics due to their associated extreme winds.

Skillful predictions of MCAOs and extratropical winter storms on subseasonal timescales have been linked to the strength of the stratospheric polar vortex. Using ERA-Interim reanalysis (1979-2019) and ECMWF forecasts from the S2S Prediction Project database we investigate the stratospheric influence on surface extremes such as MCAOs and high-impact winter storms. Following weak stratospheric vortex extremes, anomalous circulation patterns accompanied by increased storminess over the eastern North Atlantic are found to be strong indicators for enhanced MCAOs in high- and mid-latitudes. Understanding the role of the stratosphere in subseasonal variability and predictability of cold air outbreaks and storm tracks during winter can provide a key for a reliable forecast of severe impacts.
Upper ocean salinity variabilities in the Southern Ocean responding to the recent surface salting in perspective of climate changes
Authors: Du Ling , Ni Xubin
Published: March 2021

Water cycle have prevailed on upper ocean salinity acting as the climate change fingerprint in the numerous observation and simulation works. Water mass in the Southern Ocean accounted for the increasing importance associated with the heat and salt exchanges between Subantarctic basins and tropical oceans. The circumpolar deep water (CDW), the most extensive water mass in the Southern Ocean, plays an indispensable role in the formation of Antarctic Bottom Water. In our study, the observed CTDs and reanalysis datasets are examined to figure out the recent salinity changes in the three basins around the Antarctica. Significant surface salinity anomalies occurred in the South Indian/Pacific sectors south of 60ºS since 2008, which are connected with the enhanced CDW incursion onto the Antarctic continental shelf. Saltier shelf water was found to expand northward from the Antarctica coast. Meanwhile, the freshening of Upper Circumpolar Deep Water(UCDW), salting and submergence of Subantarctic Mode Water(SAMW) were also clearly observed. The modified vertical salinity structures contributed to the deepen mixed layer and enhanced intermediate stratification between SAMW and UCDW. Their transport of salinity flux attributed to the upper ocean processes responding to the recent atmospheric circulation anomalies, such as the Antarctic Oscillation and Indian Ocean Dipole. The phenomena of SAMW and UCDW salinity anomalies illustrated the contemporaneous changes of the subtropical and polar oceans, which reflected the meridional circulation fluctuation. Salinity changes in upper southern ocean (< 2000m) revealed the influence of global water cycle changes, from the Antarctic to the tropical ocean, by delivering anomalies from high- and middle-latitudes to low-latitudes oceans.
Spatialization of physical variables in soils by geophysical, geotechnical and geostatistic methods: the Bayesian maximum entropy data fusion approach
Authors: Rabouli Sara , Dubois Vivien , Serre Marc , Gance Julien , Henine Hocine , Molle Pascal , Truffert Catherine , Clement Remi
Published: March 2021

The soil is considered as a biological reactor or an outlet for treated domestic wastewater, respectively to reduce pollutant concentrations in the flows or because the surface hydraulic medium is too remote. In these cases, the saturated hydraulic conductivity of the soil is a key is a quantitative measure to assess whether the necessary infiltration capacity is available. To our knowledge, there is no satisfactory technique for evaluating the saturated hydraulic conductivity Ks of a heterogeneous soil (and its variability) at the scale of a parcel of soil. The aim of this study is to introduce a methodology that associates geophysical measurements and geotechnical in order to better described the near-surface saturated hydraulic conductivity Ks. Here we demonstrate here the interest of using a geostatistical approach, the BME "Bayesian Maximum Entropy", to obtain a 2D spatialization of Ks in heterogeneous soils. This tool opens up prospects for optimizing the sizing infiltration structures that receive treated wastewater. In our case, we have Electrical Resistivity Tomography (ERT) data (dense but with high uncertainty) and infiltration test data (reliable but sparse). The BME approach provides a flexible methodological framework to process these data. The advantage of BME is that it reduces to kriging as its linear limiting cases when only Gaussian data is used, but can also integrate data of other types as might be considered in future works. Here we use hard and Gaussian soft data to rigorously integrate the different data at hand (ERT, and Ks measurement) and their associated uncertainties. Based on statistical analysis, we compared the estimation performances of 3 methods: kriging interpolation of infiltration test data, the transformation of ERT data, and BME data fusion of geotechnical and geophysical data. We evaluated the 3 methods of estimation on simulated datasets and we then do a validation analysis using real field data. We find that BME data fusion of geotechnical and geophysical data provides better estimates of hydraulic conductivity than using geotechnical or geophysical data alone.
A new process-based vertical advection/diffusion theoretical model of ocean heat uptake
Authors: Wolf Gabriel , Tailleux Rémi , Hochet Antoine , Kuhlbrodt Till , Ferreira David , Gregory Jonathan
Published: March 2021

Ocean heat uptake is a key process for climate change owing to its control of global mean temperature trends. To understand the underlying internal ocean processes and vertical heat transfer controlling it, ocean heat uptake has been often analysed in terms of the simple one-dimensional vertical advection diffusion model. The standard version of this model, formulated in terms of the horizontally-averaged potential temperature is known to poorly capture important effects such as isopycnal mixing, density-compensated temperature anomalies, meso-scale eddy-induced advection and the depth-varying ocean area.

To overcome this problem a new theoretical model of vertical heat transfer for the ocean heat uptake has been developed in an isopycnal framework that exploits advances achieved in the theory of water masses over the past 30 years or so. The new theoretical model describes the temporal evolution of the isopycnally-averaged thickness-weighted potential temperature in terms of an effective velocity that depends uniquely on the surface heating conditionally integrated in density classes, an effective diapycnal diffusivity controlled by isoneutral and dianeutral mixing, and an additional term linked to the meridional transport of density-compensated temperature anomalies by the diabatic residual overturning circulation. The advantage of the isopycnally-averaged construction over the horizontally-averaged construction is that all the terms that enters it have explicit analytical expressions that are more easily evaluated from observations or model outputs, as well as having clearer physical interpretations.

As a first step, the terms of this new model of ocean heat uptake are evaluated by using a range of different datasets, net surface heat flux products and temporal averages to evaluate their sensitivity to input fields. One key feature of the new model is that its effective velocity and diffusivity are positive over most of the ocean column depth. This is in contrast to the horizontally-averaged construction, in which downwelling and ant-diffusive behavior were occasionally observed in previous studies. The hope is that this insight can then be used to develop an improved representation of ocean heat uptake in simple climate models.
Monitoring snowpack evolution with meteorological reanalysis data in the Atlas Mountains
Authors: Baba Wassim Mohamed , Boudhar Abdelghani , Gascoin Simon , Hanich Lahoucine , Marchane Ahmed , Chehbouni Abdelghani
Published: March 2021

The seasonal snow cover in the Altas mountains of Morocco is an important resource, mostly because it provides melt-water runoff for irrigation during the crop growing season. However, the knowledge on physical properties of the snowpack (e.g., snow water equivalent (SWE) and snowmelt) is still very limited due to the scarcity or the lack of ground measurements in the elevated area. In this study we suggest that the recent progresses of meteorological reanalysis data (e.g., MERRA-2 and ERA-5) open new perspectives to overcome this issue. We fed a distributed snowpack evolution model (SnowModel) with downscaled ERA-5 and MERRA-2 reanalyses and evaluate their performance to simulate snow cover. The modeling covers the period 1981 to 2019 (37 water years). SnowModel simulations were assessed using observations of river discharge, snow height and snow cover area derived from MODIS.

For most of hydrological years, the results show a good performance for both MERRA-2 and ERA-5 with a slight superiority of ERA-5, to reproduce the snowpack state.

Key words: snow, snow water equivalent, reanalysis , MERRA-2, ERA-5
Global Teleconnections to the Indian Summer Monsoon in CFSv2 model: Tropics vs. Midlatitude
Authors: Singhai Priyanshi , Chakraborty Arindam , Rajendran Kavirajan , Surendran Sajani
Published: March 2021

Traditionally, monsoon teleconnections are measured in terms of the strength of a simultaneous linear relationship. Such associative metrics do not quantify precipitation variations through physical parameters directly related to the moisture budget of the atmosphere. In this study, for the first time, we develop a linear model for the Indian summer monsoon rainfall (ISMR) based on surface pressure over regions surrounding it and sea surface temperature (SST) forcing from tropics and midlatitude. This surface pressure acts as a dynamical link between SST forcing and convective processes over the Indian region, which was missing in previous studies. We also use this novel approach to understand the ISMR prediction skill in the National Centers for Environmental Prediction (NCEP) Climate Forecast System version 2 (CFSv2). We find that the interannual variability of ISMR does not rely solely on tropical processes, but the midlatitude phenomenon also plays a crucial role in modulating it. The model, however, derived most of its variability from the ENSO mode. The understated midlatitude forcing in the model can be attributed to its low prediction skill. 
Mapping parent material using data originating from Earth Observation as ancillary information
Authors: Takáts Tünde , Mészáros János , Albert Gáspár , Pásztor László
Published: March 2021

Parent material is an essential soil property, whose mapping is a challenging task. Usually, large scale geological maps are used if they are available. However, in many cases, especially in medium and large scale mapping, such source data are too old or not existing at all. In this project have been looking for a solution for this problem. Our aim is to create a new, large scale, lithological map of parent material in an old mining region.

The study area is the Dorogi Basin in northern central Hungary. It is known for coal mining, which ended in 2003 after more than two centuries. The latest large scale (1:10,000) geological map series from this area was made in the 1960’s, in the “golden age” of mining.

Google Earth Engine was selected as main GIS platform, using mainly open source data and programs for mapping. We have used data originating from Earth Observation as ancillary information (e.g. satellite images, SRTM) and machine learning techniques to spatially predict parent material. The satellite images were used to calculate several geological indices, which can be used as indicators of chemical composition. We examined the use of multiple satellite platform (Sentinel-2, Landsat 8, ASTER) as it has different geological indices. The existing geological maps were used for training in the classification concerning the lithological composition.To predict the parent materials we have used random forest, using geomorphometric features and geological indices as predictors. The newly compiled map was validated by comparing it with the old one.

Acknowledgment: Our research was supported by the Hungarian National Research,Development and Innovation Office (NKFIH; K-131820) and from the part of G.A. financial support was provided from the NRDI Fund of Hungary, Thematic Excellence Programme no. TKP2020-NKA-06 (National Challenges Subprogramme) funding scheme.
Switchback-like structures observed by Solar Orbiter
Authors: Fedorov Andrey , Louarn Philippe , Owen Christopher , Prech Lubomir , Horbury Timothy , Barthe Alain , Rouillard Alexis , Kasper Justin , Bale Stuart , Bruno Roberto , O’Brien Helen , Evans Vincent , Angelini Virginia , Larson Davin , Livi Roberto ,   SWA-PAS, MAG, SWEAP, and FIELDS teams
Published: March 2021

During 27th September 2020 NASA Parker Solar Probe (PSP) and ESA-NASA Solar Orbiter (SolO) have been located around the same Carrington longitude and their latitudinal separation was very small as well. Solar wind plasma and magnetic field data obtained throughout this time interval  allows to consider that sometimes the solar wind, observed by both spacecrafts, originates from the same coronal hole region. Inside these time intervals the SolO radial magnetic field experiences several short variations similar to the "switchbacks" regularly observed by PSP. We used the SolO SWA-PAS proton analyzer data to analyze the ion distribution function variations inside such switchback-like events to understand if such events are really "remains" of the alfvenic structures observed below 60 Rs.
Transient small-scale brightenings in the quiet Sun corona: a model for "campfires" observed with Solar Orbiter
Authors: Chen Yajie , Przybylski Damien , Peter Hardi , Tian Hui
Published: March 2021

Recent observations by the Extreme Ultraviolet Imager (EUI) onboard Solar Orbiter have revealed prevalent small-scale transient brightenings in the quiet solar corona termed campfires. To understand the generation mechanism of these coronal brightenings, we constructed a self- consistent and time-dependent quiet-Sun model extending from the upper convection zone to the lower corona using a realistic 3D radiation MHD simulation. From the model we have synthesized the coronal emission in the EUI 174 Å passband. We identified several transient coronal brightenings similar to those in EUI observations. The size and lifetime of these coronal brightenings are 2–4 Mm and ∼2 min, respectively. These brightenings are located at a height of 2–4 Mm above the photosphere, and the surrounding plasma is often heated above 1 MK. These findings are consistent with the observational characterisation of the campfires. Through a comparison of the magnetic field structures before and after the occurrence of brightenings, we conclude that these coronal brightenings are generated by component magnetic reconnection between interacting bundles of field lines or the relaxation of highly twisted flux ropes. Occurring in the coronal part of the atmosphere, these events show no measurable signature in the photosphere. These transient coronal brightenings may play an important role in heating of the local coronal plasma.
Synchronizing Rock Clocks in the Cambrian
Authors: Zhao Zhengfu , Thibault Nicolas , Dahl Tais W. , Schovsbo Niels H. , Sørensen Aske L. , Rasmussen Christian M.Ø. , Nielsen Arne T.
Published: March 2021

Profound environmental and biological changes took place during the Cambrian, yet, compared to other Phanerozoic intervals, the Cambrian time framework remains poorly constrained, which severely hinders a detailed understanding of the timing and progression of these major geological events. In this study, we report a radiometrically anchored astrochronologic framework across the late Cambrian interval, using high-resolution aluminum (Al) series (1 mm resolution) through the Alum Shale Formation in Scania, southernmost Sweden, based on the fully cored Albjära-1 well. Significant cycles with periods of 405 kyr (long eccentricity), 108 kyr (short eccentricity), 30.4 kyr (obliquity) and 18.8 kyr (precession), associated with long-term amplitude modulation of obliquity and precession, confirmed the orbital imprint on late Cambrian climate. Using the U-Pb dating at 486.78±0.53Ma for the Cambro-Ordovician boundary as anchor point, our timescale spans from ~483.9 to ~500.0 Ma, covering 7 trilobite superzones and 3 graptolite zones. The calibration indicates ages of 491.2±0.54 Ma, 493.9±0.67 Ma, 497.3±0.67 Ma and 500.4±0.67 Ma for the lower boundaries of provisional Stage10, Jiangshanian, Paibian and Guzhangian stages, respectively. This radiometrically anchored astrochronology also provides precise age constrains on regional superzones or even biozones within Scandinavia, and hopefully pave the way for better understanding the late Cambrian major geological events globally.
Rising CO2 concentrations reduce nitrogen availability in alpine grasslands
Authors: Rosbakh Sergey , Auerswald Karl , Poschlod Peter
Published: March 2021

Alpine grasslands, local biodiversity hotspots with very high nature conservation and cultural value, belong to the most affected by global change ecosystems. Yet, the potential effects of others than global warming factors on alpine plant functioning is poorly understood. To address this gap, we made use of 360 herbarium specimens from nine vascular plant species collected in the Bavarian Alps, Germany, extending back 200 years to reconstruct historical changes in foliar N content and stable isotope composition (δ15N), indicators of plant response to long-term N atmospheric deposition and rising atmospheric CO2 concentrations ([CO2]). These changes were interpreted in terms of three competing hypothesis (eutrophication, oligotrophication and photorespiration), representing alternative explanations for the response of plants to changes of N and CO2 availability.

Foliar δ15N decreased significantly over time but an explanation by an increased input of reactive N from long-distance transport (’eutrophication’ hypothesis) was unlikely because foliar N contents decreased significantly as well. An increased carbon gain due to increasing [CO2] (‘oligotrophication’) also was unlikely because instantaneous water use efficiency remained unchanged and indicated no increase in C gain. The detected patterns agreed well with the ‘photorespiration’ hypothesis that biochemically links N assimilation and carbon assimilation. Increasing concentration of ambient CO2 that decreases photorespiration explained decreasing δ15N values (R2 = 0.84, p < 0.001) and decreasing N contents (R2 = 0.40, p < 0.036).

Our results suggest that increasing [CO2] by suppressing photorespiration reduces N availability to alpine plants. These findings contradict the generally accepted assumption of negative effects of eutrophication on alpine grasslands caused by air-borne N deposition. We conclude that increasing [CO2] should be considered as alternative driver of long-term changes in alpine ecosystems, as it affects directly the plant C:N stoichiometry, a key plant trait determining several important ecosystem processes.
The impact of storage conditions on heat losses of HT-ATES systems
Authors: Beernink Stijn , Bloemendal Martin , Hartog Niels
Published: March 2021

Heating and cooling is responsible for about 50% of the European total energy use. Therefore, renewable sources of heat are needed to reduce GHG emissions (e.g. solar, geothermal, waste-heat). Due to a temporal and spatial mismatch between availability and demand of heat, large scale heat storage facilities are needed. High Temperature Aquifer Thermal Energy Storage (HT-ATES) systems are one of the cheapest and most adequate ways to store large amounts of sensible heat. Regular/Low-T ATES systems are considered a proven technology with currently more than 3 000 systems operable world-wide. However, at higher storage temperatures (e.g. 40-100 °C) temperature dependent water properties (density, viscosity) more strongly affect physical processes, resulting in higher and unpredictable heat losses. While first applications and research on this subject started more than 50 years ago, many uncertainties still remain. In this research we study the (hydrogeological) storage conditions that affect the heat losses of HT-ATES systems. Numerical simulations of a wide range of storage conditions, are done to obtain generic insights in the performance of HT-ATES systems. These insights allow to identify which heat transport processes dominate in contribution to heat losses. Results show that conduction always contributes to heat losses for HT-ATES systems and relate to geometric storage conditions. While buoyancy flow (free convection) may also contribute considerable to heat losses under specific conditions.
Pathways to a sustainable, inclusive and healthy food system
Authors: Gaupp Franziska
Published: March 2021

Currently, the global food system is the single largest threat to people and planet. Food is the leading cause behind transgressing five of the nine planetary boundaries. It is a major source of carbon emissions, as well as the single largest contributor to global deforestation, overuse of fresh water and eutrophication of our aquatic ecosystems. And while agriculture has been a major engine of poverty reduction, agricultural activities are unable to deliver a decent livelihood for an estimated 80 percent of those living in extreme poverty. The projected increase in frequency and severity of climate extreme events is posing additional threats to the global food system.

A transformation towards a more inclusive, sustainable and health-promoting food system is urgently needed. This presentation will introduce the newly established Food Systems Economics Commission (FSEC) that provides detailed and robust evidence assessing the implications of the policy and investment decisions needed to foster a food system transformation. It integrates global modelling tools such as integrated assessment modelling and innovative applications of agent-based modelling with political economy considerations.  It investigates the hidden costs of our current food system, explores transitions pathways towards a new food and land use economy and suggests key policy instruments to foster the transformation towards a sustainable, inclusive, healthy and resilient food system.
Differences in the parameters and calibration efficiencies of two HBV model types
Authors: Brziak Adam , Kohnová Silvia , Kubáň Martin , Szolgay Jan
Published: March 2021

Accurate modeling of discharges in catchments plays important role in solving a large variety of water management tasks. Rainfall-runoff models are widely used for the estimation of the hydrological phenomena such as runoff, soil moisture, and snow water equivalent, etc. Three basic error factors may affect modeled outputs: quality of input data, parameter uncertainties, and model structure. This study is focused on a comparison of the performance of the lumped and semi-distributed version of the conceptual rainfall-runoff TUW model, which represents two different model structures. We focused on how the model structure can affect the parameters and the runoff model efficiencies. For that purpose, we select the 180 Austrian catchments with different morphological and geographical characteristics. We analysed the variability of efficiencies and parameters of both the HBV models types which are calibrated on discharge in the period from 1991 to 2000. As a result, we can conclude that the semi-distributed version of the HBV type model performs better, with the lower spread of the parameters and better runoff model efficiencies in both Lowland and Alpine catchments types.
High-Resolution Chronostratigraphy for Sedimentary Rocks using Rock Magnetics
Authors: Kodama Kenneth
Published: March 2021

Rock magnetics can be used to identify orbitally-forced global climate cycles in sedimentary rock sequences. The identification of Milankovitch cycles with nominal periods of 20, 40, 100 and 400 ka can be used to construct a high-resolution chronostratigraphy for a rock sequence that can have a variety of important geologic applications. Several examples will be presented. The rock magnetic cyclostratigraphy of Eocene marine, deltaic mudstones and marls of the Arguis Formation illustrates how rock magnetics can be used to determine the deformation rates of a salt tectonics growth fold in the Pyrenees. The duration of the Ediacaran Shuram carbon-isotope excursion was determined to be 8-9 Ma from rock magnetic cyclostratigraphy studies of marine rocks from Death Valley, California (Rainstorm member of the Johnnie Formation), southern Australia (Wonoka Formation), and in central and southern China (Doushantuo Formation).  Further cyclostratigraphic study of the Rainstorm member in the Desert Range, Nevada, allowed the construction of a high-resolution magnetostratigraphy by combining and calibrating magnetostratigraphic results from Death Valley and Nevada to reveal a high reversal rate of 12.7 reversals/Ma in the Ediacaran. More detailed study of the Doushantuo Formation at Huangliaba, China indicated that even though its ferromagnetic minerals were predominately secondary pyrrhotite, magnetic susceptibility measurements could still detect a depositional, orbitally-forced cyclostratigraphy carried by paramagnetic minerals. Finally, the Carboniferous Mauch Chunk Formation red beds from Pottsville, Pennsylvania yielded a magnetic susceptibility cyclostratigraphy in terrestrial, fluvial sediments despite their discontinuous sedimentation. This study showed that both portable susceptibility meter measurements and lab-based measurement of rock samples could discern the same period cycles. Detailed low and high temperature magnetic susceptibility measurements indicate that the ferromagnetic mineral hematite, rather than paramagnetic clays, is the predominant carrier of the orbitally-forced global climate signal. All these studies show the power of rock magnetics for constructing a high-resolution chronostratigraphy for sedimentary rock sequences.
Cooling joints of granite as a structural cause of the tors and boulder fields of granite
Authors: Chigira Masahiro , Hirata Yasuto
Published: March 2021

Typical cooling joints of granite have been believed to be orthogonal, and characteristic topography of granitic rocks like tors and boulder fields are interpreted in combination with the cooling joints and weathering. However, most of the previous studies were performed by the observation on the ground, and the 3D observation of cooling joints and the topographic features was not sufficient. We observed tors and boulder fields of granitic rocks using UAV and 3D modelling and found that columnar joints are typical for the granite that forms tors and that boulder fields are the accumulations of rock columns as well as boulders made by the spheroidal weathering of rock columns. Tors we observed were Mt. Kinabalu of Borneo, Mt. Mizugaki, Mt. Jizo, Mt. Gozaisho, Mt. Konze and 5 other locations in Japan. We observed that tors consist of polygonal rock columns with undulating joints, more irregularly shaped than the columnar joints of volcanic rocks. The cross-sectional areas of rock columns varied from 1 to 130 m^2, much larger than typical rock columns of volcanic rocks. The rock columns of granite are typically polygonal dipyramids, of which shapes may be dependent on the cooling history of granite. Boulder fields we observed was the Kui boulder fields in Hiroshima. We found that the boulder field is the accumulation of prismatic rock columns as well as rounded rock boulders. The prismatic rock columns had basal cross-sectional areas of 0.8 m^2 on average. The rock columns had chamfering cracks at corners, which are assumed to be made during cooling and to form preliminary outlines of core stones. Core stones had surface crusts or rindlets, which exfoliate and leave more rounded core stones.

  Rainstorm-induced landslides of weathered granite reflect weathering styles of granite: Landslides that occurred recently in Japan had three types, landslides of loosened layers of decomposed granite (or micro-sheeted granite), landslides of core-stone bearing materials, and landslides of saprolite. Landslides with core-stones were particularly destructive because of their inertia. Potential sites of such landslides could be predicted using columnar joints in fresh rocks as a clue.
Prediction of the interficial tension for CO2-Water/Brine binary system based on the linear fitting method
Authors: Mutailipu Meiheriayi , Yao Qiang
Published: March 2021

Countries in the world now are trying best to conserve energy and reduce emissions, at the meantime, efficient actions are taken to tackle with global warming. Emission reduction of main greenhouse gas CO2 can be achieved efficiently via CO2 geological storage, in terms of CO2 saline aquifer storage. The gas–liquid–solid interactions such as interfacial tension determines the injectability, sealing capacity and safety of this scheme. In order to better predict the storage capacity to evaluate the storage safety, this work aims at carrying out the numercial modelling work on the interfacial tension of CO2–water/brine binary system under the reservoir temperatures and pressures condition. 

A linear relationship between the increase in average interfacial tension and molality was observed and it is a function of the ionic type. Finally, modified empirical correlations based on experimental data in the literature, using only few regression coefficients with a relatively low error for most of the experimental data in the literature, were presented to estimate the CO2–water/brinebinary system interfacial tensions under wide range of temperatures, pressures, and the ionic strength.

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A century of European wind and solar power generation variability
Authors: Wohland Jan , Brayshaw David J. , Pfenninger Stefan
Published: March 2021

To reach its goal of net greenhouse gas neutrality by 2050, the European Union seeks to massively expand wind and solar power. Relying on weather-dependent power generation, however, poses substantial risks if climate variability is not adequately understood and accounted for in energy system design. Through informed combination of centennial reanalyses that have been tested for agreement with large scale climate phenomena, we here quantify European wind and solar generation variability over the last century. We report that wind and solar generation vary on a multidecadal scale, but wind more strongly. We identify hotspots and study dominant patterns of (co-)variability, finding that solar generation varies mostly uniformly across Europe while the leading wind variability modes reveal cross-border balancing potential. Continental scale transmission thus proves useful in balancing wind power variability also on multidecadal timescales. Evaluating local solutions to balance generation variability, we find that combined wind and solar systems optimized for minimal seasonal variability exhibit multidecadal variability of around 10% in many European countries. This amplitude can be reduced three-fold through wind shares optimised for minimal multidecadal variability. Thus, with improved spatial planning only, multiple options to mitigate long-term renewable generation variability exist.
Kinetic simulations of high Mach shocks: PIC simulations vs in-situ measurements
Authors: Bohdan Artem , Pohl Martin , Niemiec Jacek , Morris Paul J. , Matsumoto Yosuke , Amano Takanobu , Hoshino Masahiro , Sulaiman Ali
Published: March 2021

High-Mach-number collisionless shocks are found in planetary systems and supernova remnants (SNRs). Electrons are heated at these shocks to temperatures well above the Rankine–Hugoniot prediction. However, the processes responsible for causing the electron heating are still not well understood. We use a set of large-scale particle-in-cell simulations of nonrelativistic shocks in the high-Mach-number regime to clarify the electron heating processes. The physical behavior of these shocks is defined by ion reflection at the shock ramp. Further interactions between the reflected ions and the upstream plasma excites electrostatic Buneman and two-stream ion–ion Weibel instabilities. Electrons are heated via shock surfing acceleration, the shock potential, magnetic reconnection, stochastic Fermi scattering, and shock compression. The main contributor is the shock potential. The magnetic field lines become tangled due to the Weibel instability, which allows for parallel electron heating by the shock potential. The constrained model of electron heating predicts an ion-to-electron temperature ratio within observed values at SNR shocks and in Saturn’s bow shock. We also present evidence for field amplification by the Weibel instability. The normalized magnetic field strength strongly correlates with the Alfvenic Mach number, as is in-situ observed at Saturn's bow shock.
Statistical Modeling of Non-Stationary Heatwave Hazard
Authors: Zhong Peng , Huser Raphael , Opitz Thomas
Published: March 2021

The modeling of spatio-temporal trends in temperature extremes can help better understand the structure and frequency of heatwaves in a changing climate, as well as their environmental, societal, economic and global health-related risks. Here, we study annual temperature maxima over Southern Europe using a century-spanning dataset observed at 44 monitoring stations. Extending the spectral representation of max-stable processes, our modeling framework relies on a novel construction of max-infinitely divisible processes, which include covariates to capture spatio-temporal non-stationarities. Our new model keeps a popular max-stable process on the boundary of the parameter space, while flexibly capturing weakening extremal dependence at increasing quantile levels and asymptotic independence. It clearly outperforms natural alternative models. Results show that the spatial extent of heatwaves is smaller for more severe events at higher altitudes and that recent heatwaves are moderately wider. Our probabilistic assessment of the 2019 annual maxima confirms the severity of the 2019 heatwaves both spatially and at individual sites, especially when compared to climatic conditions prevailing in 1950-1975. Our applied results may be exploited in practice to understand the spatio-temporal dynamics, severity, and frequency of extreme heatwaves, and design suitable regional mitigation measures.
Amplified warming of extreme temperatures over tropical land
Authors: Byrne Michael
Published: March 2021

Extreme temperatures have warmed substantially over recent decades and are projected to continue warming in response to future climate change. Warming of extreme temperatures is amplified over land where the impacts on human health, wildfire risk and food production are most severe. Using simulations with climate models, I show that hot days over tropical land warm substantially more than the average day. For example, warming of the hottest 1% of land days is 24% larger than the time-mean warming averaged across models. The climate-change response of extreme temperatures over tropical land is interpreted using a theory based on atmospheric dynamics. According to the theory, warming is amplified for hot land days because those days are dry: I term this the "drier get hotter" mechanism. Changes in near-surface relative humidity further increase tropical land warming , with decreases in land relative humidity particularly important. The theory advances physical understanding of the tropical climate and highlights land-surface dryness as a key factor determining how extreme temperatures will respond to future climate change.
Geoethics, a Philosophical Hybrid of European Origin
Authors: Bohle Martin
Published: March 2021

European philosophies shape geoethics. The Culture-Nature-Dichotomy (“appropriate behaviours and practices, wherever human activities interact with the Earth system” [1; p.30]) and the associated anthropocentric interpretation of the human condition [1; p.58-60] is an example.

The European post-medieval cultural models [2, 3] led to engage early with scientific studies of Earth [4, 5], to merge science, research, engineering, economy and applied ethics into a massive societal venture [6, 7], and to shape global hegemonic societal practices [8, 9]. These developments provide the socio-historical foundation of geoethics. It implies depicting Culture and Nature differently, respectively using either idealistic or materialistic philosophies.

Tinted by European cultural models, geoethics is based on geosciences knowledge and applies philosophical materialism when inspecting Nature. However, geoethics displays philosophical idealism when inspecting Culture, e.g. the virtuous individual's societal role [1; p.33-43]. Recently, an academic noticed: “not even a single word [in geoethics] about the structural determinations upon individuals in the particular form of social organisation where they live [a].” Such a critical view (absence to apply philosophical materialism) is valuable when considering that geoethics aims to advise about “appropriate [socio-historical/cultural] behaviours and practices”.

Such considerations point at the need to re-inspect the philosophical basis of geoethics. Merely being ‘tinted’ by European cultural models is unsatisfying. Instead, analyses should show whether to apply idealistic and materialistic philosophies. Investigating, for example, whether to inspect Culture like Nature using philosophical materialism, would test the consistency of the current philosophical hybrid, geoethics; subsequently, such analyses should elucidate geoethics’ anthropocentric bearings.

[a] anonymous review published in Quaternary (2019); https://www.mdpi.com/2571-550X/2/2/19/review_report (1st round reviewer 2 report)