bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial patterns of multi-centennial temperature trend in Antarctica over 0-1000 CE: insights from ice core records and modeling
Authors: Lyu Zhiqiang , Goosse Hugues , Dalaiden Quentin
Published: March 2021

Recent Antarctic surface climate change has been characterized by greater warming trends in West Antarctica than in East Antarctica. Although the changes over recent decades are well studied, the short instrumental record limits our ability to determine if such asymmetric patterns are common for Antarctica and the processes at their origin. Here, we will focus on the years 0-1000 CE as some ice core records display very contrasted trends during this period. Furthermore, the climate models are unable to reproduce the warming displayed in some reconstructions from 1 to 500 CE over East Antarctica. In order to understand the origin of these apparent incompatibilities and investigate the effect of proxy selection on regional reconstructions over 0-1000 CE, we performed several offline data assimilation experiments based on different groups of d18O records and the isotope-enabled general circulation models (iCESM). When assimilating different d18O data sets, large differences appear in the pattern of temperature trend over 0-500 CE, but the patterns over 500-1000 CE are more consistent among the various experiments. This implies that the spatial pattern of temperature trend over 0-500 CE is still uncertain because of this high sensitivity on the choice of the proxies to constrain the model results, while the pattern over 500-1000 is more robust, with the greater cooling over West Antarctica than East Antarctica. This pattern over 500-1000 CE relates to the intensifying of the low pressure centered in the Amundsen Sea, which induces enhanced southerly flow through most of WAIS.
Applying the Values of Geoethics for Sustainable Speleotourism Development
Authors: Antić Aleksandar , Di Capua Giuseppe , Peppoloni Silvia
Published: March 2021

Establishing sustainable and responsible speleotourism development is a major challenge and involves complex activities. Adequate theoretical starting point is the application of geoethical values related to the conservation and protection of the caves to be used for touristic purposes. Positive and negative cases of human behaviors towards speleological geoheritage are discussed, in order to highlight what should be done in cave management to avoid malpractices and on what elements could be founded adequate strategies aimed at promoting sustainable speleotourism. This is important to tourism management organizations involved in the promotion of caves and in creating economic opportunities for local populations, while respecting cave ecosystems. Modern cave management must be focused on the protection of the cave ecosystems, finding ways to achieve at the same time an economic development of local communities. But this approach needs the adoption of a geoethical framework of values to be shared by all stakeholders involved so that successful cooperation can be achieved despite differences in interests and expectations. The aim of this paper is to raise the awareness about the need to apply the values of geoethics to speleotourism, stimulating new fields of discussion within the scientific and technical communities involved in studies and activities related to geotourism and geoheritage. The possibilities of developing new ways to manage caves, in order to promote a sustainable socio-economic development of local communities, have to be balanced with the protection of natural environments as much as possible. The proposed theoretical frameworks have the goal to increase the discussion on the best ways of connecting speleotourism to sustainable and responsible cave management, presenting two case studies, and pointing out potential solutions.
What happens with the Ekman current under constant wind?
Authors: Shrira Victor , Almelah Rema
Published: March 2021

The work examines the Ekman current  response to a steady
wind within the Stokes-Ekman paradigm. Under constant wind
in the classical Ekman model there is a single attractor
corresponding to the Ekman (1905)steady solution. It is
known that the account of wind waves  strongly affects the
Ekman current dynamics via the Stokes drift, which is
described by the Stokes-Ekman  model. Waves continue to
evolve even under constant wind, which makes  steady
solutions of the Stokes-Ekman equation impossible. Since
the dynamics of the Ekman response in the presence of
evolving wave field have not been considered,  the basic
questions on how  the Ekman current evolves and,
especially, whether it grows or decays at large times,
remain open.

Here by employing the known self-similar laws of wave
field evolution and  solving analytically the
the Stokes-Ekman equation we  find and analyse
evolution of the Ekman current. We show that the system has
a single time dependent attractor which can be described
asymptotically. The large time asymptotics of the Ekman
current is found to be determined by the regime of wave
field evolution:  for the regimes typical of young waves
 the Ekman current grows with time to infinity, in contrast, for
`old waves'  the Ekman current asymptotically decays.

 
Climatic control on the Southern Andean volcanic arc location
Authors: Paiva Muller Veleda Astarte , Sternai Pietro , Sue Christian
Published: March 2021

The Southern Andes Volcanic zone (SVZ) is located between latitudes 33-46°S in the western margin of the South American continental plate, above the subducting Nazca oceanic plate. Although the slab dip angle is constant (~25°) along strike, the distance between the volcanic arc and the subduction trench decreases southward. In the northern segment (33-41°S) the volcanoes are co-located with the main orogenic water divide, whereas in the southern segment (41-46°S) the water divide is shifted eastward and the volcanic arc is shifted westward. The eastward water divide migration in the southern segment is explained by an orographic effect due to the westerlies winds, which causes high precipitation (>2 m/yr) and erosion rates (>1.5 mm/yr) on the upwind side of the orogen. Thermomechanical visco-elasto-plastic numerical models exploring the effects of the topographic shift on the magma upwelling path explain the westward migration of the volcanic arc. Results show that when the topographic barrier is shifted to the east with respect to a central magmatic source, asymmetric strain due to the magma emplacement into the crust drives preferential westward magma upwelling. The southern segment of the SVZ is proximal to an important strike slip fault system, the Liquiñe-Ofqui fault zone. We propose that the (re-)activation of these fracture zone on the western side of the Southern Andes is related to the orographic migration of the water divide during magma upwelling. This conclusion is further supported by the lack of structures accommodating magma emplacement/eruption and volcanoes east of the water divide. If correct, this is the first-recognized example of a climatic control on the location of a volcanic arc in convergent settings.
Numerical Modelling of a District Scale Groundwater Heat Pump Operation: Case Study from Colchester, UK
Authors: Sezer Taha , Sani Abubakar Kawuwa , Singh Rao Martand , Boon David P.
Published: March 2021

Groundwater heat pumps (GWHP) are an environmentally friendly and highly efficient low carbon heating technology that can benefit from low-temperature groundwater sources lying in the shallow depths to provide heating and cooling to buildings. However, the utilisation of groundwater for heating and cooling, especially in large scale (district level), can create a thermal plume around injection wells. If a plume reaches the production well this may result in a decrease in the system performance or even failure in the long-term operation. This research aims to investigate the impact of GWHP usage in district-level heating by using a numerical approach and considering a GWHP system being constructed in Colchester, UK as a case study, which will be the largest GWHP system in the UK. Transient 3D simulations have been performed pre-construction to investigate the long-term effect of injecting water at 5°C, into a chalk bedrock aquifer. Modelling suggests a thermal plume develops but does not reach the production wells after 10 years of operation. The model result can be attributed to the low hydraulic gradient, assumed lack of interconnecting fractures, and large (>500m) spacing between the production and injection wells. Model validation may be possible after a period operational monitoring.
An investigation into edge-wave generation by wind
Authors: Sheremet Alex , Troitskaya Yulia. I. , Soustova Irina , Shrira Victor I.
Published: March 2021

Edge waves (EW) are surface gravity waves topographically trapped near the highly reflective ocean shorelines. Over mildily sloping beaches, the high-reflectivity condition is only satisfied for infragravity waves (IGW, periods of a few minutes). Initially believed to drive alongshore-periodic shoreline features, EW have been shown to be important also for a variety of coastal ocean processes such as nonlinear shoaling of wind waves, coastal flooding, ice-shelf break up in polar oceans, and others.  As IGW, on mildly sloping beaches EW are outside the wind-wave frequency range, which seems to exclude direct wind forcing as generating mechanism. It is generally agreed that IGW ove mildly sloping beaches are generated by nonlinear swell interaction.

Wave-wave interactions can excite both alongshore progressive and standing EW, but EW directional symmetry should match swell directionalty. This simple rule is confirmed also by observations. Exceptions to thius rule are intriguing: if directionally-asymmetric edge waves fields that do not match the swell direction, occur, the implication is that wave-wave interactions are not the dominant IGW/EW generation mechanism. Direct wind forcing would then be the only conceivable candidate. The high correlation of swell and IG wave directionality, however, suggests that such occurrences must be rare, possibly associated with peculiar coastal weather conditions. 

We investigate data produced by the most comprehensive effort to date to study EW - the nearshore array deployed by Elgar, Herbers, O'Reilly and Guza during the SandyDuck'97 experiment - which recorded pressure and velocity continuously at 2 Hz from August to December 1997, at sensors distributed on six alongshore lines between approximately the 1-m and 6-m isobaths near the Duck NC pier. Estimates directional IGW/EW match well swell directionality. However, a few events exhibit strong IG/EW directional asymmetry matching wind direction, with nearly shorenormal offshore swells. In most of these cases, IGW propagate against the nearshore current. These events are consistent with a mechanism for direct generation of IGW/EW by wind. It is not clear whether their scarcity is due to intrinsic properties of the wind generation mechanism, or to the rather low-energy conditions of the SandyDuck'97 experiment. In general, both nonlinear wave-wave interactions and wind generation should be taken into account, and we expect the wind generation mechanism to play an increasingly important role in storms, for example, for modeling wave surges. An investigation into modeling EW generation by wind will be reported elsewhere. 

 
A pause in Southern Hemisphere circulation trends due to the Montreal Protocol
Authors: Banerjee Antara , Fyfe John C. , Polvani Lorenzo M. , Waugh Darryn , Chang Kai-Lan
Published: March 2021

Observations show robust near-surface trends in Southern Hemisphere tropospheric circulation towards the end of the twentieth century, including a poleward shift in the mid-latitude jet, a positive trend in the Southern Annular Mode and an expansion of the Hadley cell. It has been established that these trends were driven by ozone depletion in the Antarctic stratosphere due to emissions of ozone-depleting substances. Here we show that these widely reported circulation trends paused, or slightly reversed, around the year 2000. Using a pattern-based detection and attribution analysis of atmospheric zonal wind, we show that the pause in circulation trends is forced by human activities, and has not occurred owing only to internal or natural variability of the climate system. Furthermore, we demonstrate that stratospheric ozone recovery, resulting from the Montreal Protocol, is the key driver of the pause. Because pre-2000 circulation trends have affected precipitation, and potentially ocean circulation and salinity, we anticipate that a pause in these trends will have wider impacts on the Earth system. Signatures of the effects of the Montreal Protocol and the associated stratospheric ozone recovery might therefore manifest, or have already manifested, in other aspects of the Earth system.
The predictive power of wood traits on species mortality change during tree development 
Authors: Gonzalez-Melo Andres , Posada Juan
Published: March 2021

One foundational assumption of trait-based ecology is that functional traits can predict species demography. Yet, in general, the links between traits and demographic rates are not as strong as usually assumed. These weak associations may be due to two main reasons: the use of easy-to-measure traits as proxies of tree species performance, and the lack of consideration of size-related variations in both traits and demographic rates.

Here, we examined the associations between wood functional traits and mortality rates of 19 tree species from Eastern Amazonia. We measured eleven wood traits (i.e., structural, anatomical and chemical) in sapling, juvenile and adult wood, and related them to corresponding mortality rates.

Both sapling and juvenile mortality rates were best explained by wood specific gravity (WSG) and vessel lumen area (Va), while adult mortality was predicted only by Va. On the other hand, we found that the predictive power of wood trait on mortality rates decreased from saplings to adults.

These results indicate that the associations between traits and mortality rates can change during tree development, and also that hard-to-measure traits, such as wood chemical or anatomical traits, may be better predictors mortality rates than WSG. Our findings are important to expand our knowledge on tree life-history variations and community dynamics in tropical forests.

 

 
Mineral protection regulates the long-term global preservation of natural organic carbon
Authors: Hemingway Jordon , Rothman Daniel , Grant Katherine , Rosengard Sarah , Eglinton Timothy , Derry Louis , Galy Valier
Published: March 2021

The vast majority of organic carbon (OC) produced by life is respired back to carbon dioxide (CO2), but roughly 0.1% escapes and is preserved over geologic timescales. By sequestering reduced carbon from Earth’s surface, this “slow OC leak” contributes to CO2 removal and promotes the accumulation of atmospheric oxygen and oxidized minerals. Countering this, OC contained within sedimentary rocks is oxidized during exhumation and erosion of mountain ranges. By respiring previously sequestered reduced carbon, erosion consumes atmospheric oxygen and produces CO2. The balance between these two processes—preservation and respiration—regulates atmospheric composition, Earth-surface redox state, and global climate. Despite this importance, the governing mechanisms remain poorly constrained. To provide new insight, we developed a method that investigates OC composition using bond-strength distributions coupled with radiocarbon ages. Here I highlight a suite of recent results using this approach, and I show that biospheric OC interacts with particles and becomes physiochemically protected during aging, thus promoting preservation. I will discuss how this mechanistic framework can help elucidate why OC preservation—and thus atmospheric composition, Earth-surface redox state, and climate—has varied throughout Earth history.
Stability of the Atlantic overturning circulation under intermediate (MIS3) and full glacial (LGM) conditions and its relationship with Dansgaard-Oeschger climate variability
Authors: Zhang Xiao
Published: March 2021

Paleoclimatic records reveal that millennial-scale climate variability during the Pleistocene was most pronounced during intermediate glacial conditions, like Marine Isotope Stage 3 (MIS3), rather than during interglacial and fully glaciated climates, like the Last Glacial Maximum (LGM). The rapid transitions between cold stadials and warm interstadials recorded in Greenland ice cores during MIS3, referred to as DansgaardeOeschger (D-O) events, have been correlated with millennial-scale climate variations worldwide. Although the origin of D-O events is a matter of controversy, striking evidence shows that
variations in the strength of the Atlantic meridional overturning circulation (AMOC) were involved.Therefore, understanding the stability properties of the ocean circulation under different background climate conditions is key to understanding D-O millennial-scale climate variability. In the present study,the stability of the AMOC to northern high-latitude freshwater perturbations under MIS3 and LGM boundary conditions is investigated by using the coupled climate model CCSM3. Stability diagrams constructed from a large set of equilibrium experiments reveal a nonlinear dependence of AMOC
strength on freshwater forcing under both MIS3 and LGM conditions. The MIS3 baseline state is close to an AMOC stability threshold, which makes the MIS3 climate unstable with respect to minor perturbations. A similar threshold behavior in AMOC stability is observed under LGM conditions; however, larger freshwater perturbations are necessary to pass the threshold and weaken the AMOC. The threshold’s displacement relative to the MIS3 background climate is attributable to differences in the atmospheric hydrologic cycle and North Atlantic sea ice transport. Different atmospheric moisture transports are attributable to thermodynamic and dynamic processes related to differences in greenhouse gas forcing and ice-sheet height between MIS3 and the LGM. We conclude that the higher stability of the AMOCduring the LGM is a physically plausible explanation for millennial-scale D-O-type climate variability being suppressed under full glacial conditions, whereas minor perturbations in freshwater fluxes could
have triggered D-O climate shifts during MIS3.
How do silicious trichomes influence leaf decomposition by meso- and macrofauna?
Authors: Nakamura Ryosuke , Amada Gaku , Kajino Hirofumi , Morisato Kei , Kanamori Kazuyoshi , Hasegawa Motohiro
Published: March 2021

Decomposition of plant leaves is influenced by multiple traits, however, discrete structures of Si such as silicious trichomes on the leaf surface have been overlooked, although similarly to defense against insect herbivores, trichomes are thought to protect leaves from decomposers. This study hypothesized that silicious trichomes slow down leaf decomposition by soil meso- and macrofauna. We used two mesh bags (<0.2 mm and 5 mm) and examined ash-free mass loss of green leaves of Broussonetia papyrifera and Morus australis, closely related Moraceae species apparently different in trichome size and density, after 25 days of decomposition in a common garden. We also measured 10 traits of initial leaves and performed microscopic observation of the leaf surface with an energy dispersive X-ray analyzer. Of the leaf traits, trichome density on the lower leaf surface differed greatly between the two species. Our microscopic observation showed that short trichomes densely arranged on the lower leaf surface of B. papyrifera were highly silicified and that some of long trichomes were also composed of calcium. Ash-free mass loss of M. australis was greater in 5-mm mesh bag than in <0.2-mm mesh bag, while that of B. papyrifera did not differ by mesh size, which represents a suppressive effect of silicious trichomes on decomposition by meso- and macrofauna. The trichomes of B. papyrifera remained apparently intact on the decomposed surface, supporting a view of their continuously deferring influence on the large decomposers during the experimental period. For the meso- and macro-detritivore community, three taxa (Acari, Collembola and Isopoda) showed high population density in the common garden. Overall, our results suggest that distinct forms of Si bodies in plants such as trichomes are worth considering in better understanding of leaf decomposition by meso- and macrofauna.
Impact of post-wildfire stabilization treatments on major and minor topsoil elements in a Mediterranean environment (Croatia): first-year study
Authors: Delač Domina , Pereira Paulo , Kisić Ivica
Published: March 2021

In the Mediterranean part of Croatia, wildfires have increased in recent decades raising concerns about soil degradation. Post-wildfire stabilization treatments are used in fire affected areas due to their easy application and possible beneficial effects on soil quality. On 28 July 2019, a moderate to high severity wildfire affected about 900 ha in the central part of Mediterranean, Croatia (43°45'N 15°56'E; 105 m a.s.l.). Wildfire mostly affected abandoned grassing with a dominant culture Aleppo pine (Pinus halepensis), and olive groves (Olea europaea). The effects of wildfire (control (C); uncovered burned soil), and two post-wildfire stabilization treatments (mulches); pine needles (PM) and olive leaves (OM) were evaluated on soil samples (0–5 cm depth) taken during 5 sampling campaigns; 25 days after fire (DAF), 3 months after fire (MAF), 6 MAF, 9 MAF, and 12 MAF. One treatment covered 10 m2, and mulches were applied in 0.5 kg m-2. The non-destructive analytic method, X-ray fluorescence (pXRF), was used to determine the behavior of total concentrations of nutrients and pollutants in all soil samples. The results showed that Al and P were significantly lowest at PM 12 MAF compared to other dates. The P was also significantly lowest at C 3 MAF than other dates. The Ti was significantly lowest at PM 12 MAF then C treatment, while the Zn was significantly different between PM and OM treatments 12 MAF, with highest values at PM. The Si didn’t vary significantly under mulch treatments, but in C was significantly highest 12 MAF in regard to 25 DAF. The K was significantly highest at both mulch treatments 3 MAF, regard to other dates and C treatment. The Pb showed significant changes only in PM between 3 and 12 MAF, with highest concentrations 12 MAF. The S showed significant difference in C between 25 DAF and 12 MAF with the highest 25 DAF. The effects of fire and mulches during the first post-fire year didn’t show significant change of Ca, V, Cr, Mn, Fe, Co, Ni, Cu, As, Rb, Sr, Y, Zr, Nb, and Th concentrations. These results show that PM had a more notable impact on the concentrations of major and minor topsoil elements in comparison to OM. However, it is concluded that more time is required to complete mulch decomposition and possible increment in soil quality.

Acknowledgments: The work was supported by Croatian science foundation under the project “Influence of Summer Fire on Soil and Water Quality” (IP-2018-01-1645).
Equality of opportunities in geosciences: The EGU Awards Committee experience
Authors: Blunier Thomas
Published: March 2021

EGU, the European Geosciences Union, is Europe’s premier geosciences union, dedicated to the pursuit of excellence in the Earth, planetary, and space sciences for the benefit of humanity, worldwide. Every year, the EGU awards and medals programme recognises eminent scientists for their outstanding research contribution in the Earth, planetary and space sciences. In addition, it identifies the awardees as role models for the next generation of early career scientists to foster geoscience research.

Nominations for all the medals and awards are submitted every year online by 15 June by the members of the EGU scientific community. Any person can be nominated except the EGU president, vice-president council members (not including ex- officio members) and chairs of the EGU committees. The EGU Council, the medal and award committees’ members and the Union and division officers are committed to soliciting nominations of deserving individuals by avoiding conflicts of interest. Each EGU medal or award is selected through a rigorous assessment of the candidates and their merits through the respective committee. The procedures for nomination, selection of candidates and the time schedule are described in detail on EGU websites.

It is a strict necessity when recognizing scientific excellence by any scientific association providing equal opportunities and ensuring balance. The processes and procedures that lead to the recognition of excellence has to be transparent and free of gender biases. However, establishment of clear and transparent evaluation criteria and performance metrics in order to provide equal opportunities to researchers across gender, continents and ethnic groups can be challenging since the definition of scientific excellence is often elusive.

This presentation aims to present the experience and the efforts of the European Geosciences Union to ensure equal opportunities. Data and statistics will be presented in the attempt to provide constructive indications to get to the target of giving equal opportunities to researchers across gender, continents and ethnic groups.
Bathymetry estimation from altimeter - derived gravity data in the Adriatic Sea
Authors: Vrdoljak Ljerka , Grgić Marijan , Bašić Tomislav
Published: March 2021

Bathymetric models representing the topography of the seafloor are an important parameter in almost all maritime related research. Traditional bathymetric shipborne or airborne surveys are cost and/or time consuming, and access to the measured data is mostly limited or expensive. Alternative bathymetric data sources for marine researchers are publicly available bathymetric models whose quality is often unknown and/or uneven. This research presents the study on the bathymetric prediction for the Adriatic Sea from altimetry-derived gravity anomalies and in-situ soundings using the gravity - geologic method (GGM). Bathymetric soundings used to determine the density contrast between seawater and bedrock were derived from nautical charts, EMODnet (European Marine Observation and Data Network) bathymetric grid, and GEBCO (General Bathymetric Chart of the Oceans) One Minute grid. More than 3000 chart soundings distributed across the Adriatic Sea were used to estimate the quality of the predicted bathymetric model as well as the quality of the latest versions of publicly available bathymetric models: DTU10Bat (Technical University of Denmark), GEBCO 2020, EMODnet 2018, ETOPO1, Smith and Sandwell v.19.1, and SRTM (Shuttle Radar Topography Mission) 15+ V.2.1. The results show that the computed model represents an update to bathymetric data in the Adriatic Sea, especially along its eastern coast.
Amorphous silica increases the water holding capacity of soils – from mechanistic understanding to field experiments
Authors: Schaller Joerg
Published: March 2021

A main problem currently facing agriculture is drought. More frequent and longer drought periods are predicted to threaten agricultural yields in future. The capacity of soils to hold water is a highly important factor controlling drought stress intensity for plants during the growing phase. Amorphous silica (ASi) has been suggested to be able to mitigate these problems. Amorphous silica pools in natural soils are in the range of 0-6%. However, ASi pools have declined in agricultural soils since the development of high intensity agriculture to values of <1% due to yearly crop harvests, decreasing the water holding capacity of the soils. Here, we analyzed the effect of ASi on the water holding capacity (WHC) of soils. ASi was mixed at varying rates with different soils. Afterwards, the retention curve of the soils was determined. Here we show that ASi increases the soil water holding capacity substantially, by forming silica gels with a water content at soil saturation higher than 700%. An increase of ASi by 1% or 5% (weight) increased the water content at all studied water potentials and plant available water increased by >40% and >60%, respectively. In a lysimeter experiment we found that ASi strongly increased the WHC of soils, too. In a field experiment we found an increase of soil moisture after ASi fertilization over the whole growing season. Furthermore, wheat plant grown in this field experiment suffered less from drought and had a later onset of senescence. Our results suggest that ASi is a main control on soil water availability, potentially decreases drought stress for plants in future.
Exploring ocean floor geodiversity in relation to mineral resources in the Pacific Ocean
Authors: Seijmonsbergen Harry , Valentijn Sanne , Westerhof Lisan , Rijsdijk Kenneth
Published: March 2021

There is a growing demand for mineral resources such as metals and rare earth elements, but global terrestrial resources are rapidly declining. Alternatively, the ocean floor provides unprecedented mining potential. However, their occurrences  in relation to ocean floor geodiversity is largely unexplored. Therefore, it is unclear what the (irreversible) potential impact of future mining is on ocean floor geodiversity.

Here, we quantify the ocean floor geodiversity of the West-Pacific ocean floor and explore the distribution of three mineral resources: polymetallic sulfides, cobalt-rich ferromanganese crusts and polymetallic nodules.  We developed a workflow for the calculation of a geodiversity index composed of openly available geomorphological, sediment thickness, bathymetric and derived ocean floor roughness input data in ArcGIS Pro.

Our results show a large variety in geodiversity on the West-Pacific ocean floor, ranging from very low and low geodiversity on large plateaus and in wide trenches and throughs, to high and very high geodiversity in heterogeneous, patchy environments on shelves, basins and abyssal plains. Regression analysis results indicate that polymetallic sulfides and cobalt-rich ferromanganese crusts positively correlate to the geodiversity index, while polymetallic nodules indicate a negative correlation.  Further analysis will focus on refining and expanding this method to a global extent by adding ocean floor age, a possible important factor, into the geodiversity assessment.

Our findings suggest that understanding of ocean floor geodiversity can contribute to promote sustainable mining and support conservation of the ocean floor.
Operational Single-Precision Earth-System Modelling at ECMWF
Authors: Hatfield Sam , Mogensen Kristian , Dueben Peter , Wedi Nils , Diamantakis Michail
Published: March 2021

Earth-System models traditionally use double-precision, 64 bit floating-point numbers to perform arithmetic. According to orthodoxy, we must use such a relatively high level of precision in order to minimise the potential impact of rounding errors on the physical fidelity of the model. However, given the inherently imperfect formulation of our models, and the computational benefits of lower precision arithmetic, we must question this orthodoxy. At ECMWF, a single-precision, 32 bit variant of the atmospheric model IFS has been undergoing rigorous testing in preparation for operations for around 5 years. The single-precision simulations have been found to have effectively the same forecast skill as the double-precision simulations while finishing in 40% less time, thanks to the memory and cache benefits of single-precision numbers. Following these positive results, other modelling groups are now also considering single-precision as a way to accelerate their simulations.

In this presentation I will present the rationale behind the move to lower-precision floating-point arithmetic and up-to-date results from the single-precision atmospheric model at ECMWF, which will be operational imminently. I will then provide an update on the development of the single-precision ocean component at ECMWF, based on the NEMO ocean model, including a verification of quarter-degree simulations. I will also present new results from running ECMWF's coupled atmosphere-ocean-sea-ice-wave forecasting system entirely with single-precision. Finally I will discuss the feasibility of even lower levels of precision, like half-precision, which are now becoming available through GPU- and ARM-based systems such as Summit and Fugaku, respectively. The use of reduced-precision floating-point arithmetic will be an essential consideration for developing high-resolution, storm-resolving Earth-System models.
2021 State of Climate Services report: Risk Information and Early Warning Systems
Authors: Grasso Veronica
Published: March 2021

Between 1970 and 2019, 79% of disasters worldwide involved weather, water, and climate-related hazards. These disasters accounted for 56% of deaths and 75% of economic losses from disasters associated with natural hazards reported during that period. As climate change continues to threaten human lives, ecosystems and economies, risk information and early warning systems (EWS) are increasingly seen as key for reducing these impacts. The majority of countries, including 88% of least developed countries and small island states, that submitted their Nationally Determined Contributions (NDCs) to UNFCCC have identified EWS as a “top priority”.

This latest multi-agency report, coordinated by WMO, highlights progress made in EWS capacity – and identifies where and how governments can invest in effective EWS to strengthen countries’ resilience to multiple weather, water and climate-related hazards. Being prepared and able to react at the right time, in the right place, can save many lives and protect the livelihoods of communities everywhere.
Quantifying plant-soil-nutrient dynamics in rangelands: Fusion of UAV hyperspectral-LiDAR, UAV multispectral-photogrammetry, and ground-based LiDAR-digital photography in a shrub-encroached desert grassland
Authors: Sankey Temuulen , Sankey Joel , Li Junran , Ravi Sujith , Wang Guan , Caster Joshua , Kasprak Alan
Published: March 2021

Rangelands cover 70% of the world’s land surface, and provide critical ecosystem services of primary production, soil carbon storage, and nutrient cycling. These ecosystem services are governed by very fine-scale spatial patterning of soil carbon, nutrients, and plant species at the centimeter-to-meter scales, a phenomenon known as “islands of fertility”. Such fine-scale dynamics are challenging to detect with most satellite and manned airborne platforms. Remote sensing from unmanned aerial vehicles (UAVs) provides an alternative option for detecting fine-scale soil nutrient and plant species changes in rangelands over smaller extents than typically imaged with satellite and manned airborne platforms. We demonstrate that a model incorporating the fusion of UAV multispectral and structure-from-motion photogrammetry classifies plant functional types and bare soil cover with an overall accuracy of 95% in rangelands degraded by shrub encroachment and disturbed by fire. We further demonstrate that employing UAV hyperspectral and LiDAR (light detection and ranging) fusion greatly improves upon these results by classifying 9 different plant species and soil fertility microsite types (SFMT) with an overall accuracy of 87%. Creosote bush (Larrea tridentata) and black grama (Bouteloua eriopoda) are the most important native species in the rangeland and have the highest producer’s accuracies at 98% and 94%, respectively. The integration of UAV LiDAR-derived plant height differences was critical in these improvements. Finally, we use synthesis of the UAV datasets with ground-based LiDAR surveys and lab characterization of soils to estimate that the burned rangeland potentially lost 1,474 kg/ha of C and 113 kg/ha of N owing to soil erosion processes during the first year after a prescribed fire. However, during the second-year post-fire, grass and plant-interspace SFMT functioned as net sinks for sediment and nutrients and gained approximately 175 kg/ha C and 14 kg/ha N, combined. These results provide important site-specific insight that is relevant to the 423 Mha of grasslands and shrublands that are burned globally each year. While fire, and specifically post-fire erosion, can degrade some rangelands, post-fire plant-soil-nutrient dynamics might provide a competitive advantage to grasses in rangelands degraded by shrub encroachment. These novel UAV and ground-based LiDAR remote sensing approaches thus provide important details towards more accurate accounting of the carbon and nutrients in the soil surface of rangelands.
The archaeological site of chellah, new technologies for investigation, modeling, and mapping.
Authors: el guertet Iman , aarab Abdellatif , larabi Abdelkader , Jemmal Mohammed , benchekroun Sabah
Published: March 2021

archaeological sites have been always a subject of curiosity and search, the archaeologists and scientists from different specialties have been wondering about the origins of the man civilization, about the way our forefathers lived, how they nourished, dressed, and housed themselves, what techniques were used for the transport, the fishing, and the business, about the culture and the spiritual practices. in fact, the modern technologies, practices, and innovations are only a continuation of what was once; this is why the human being believes it is imperative to revive and understand the heritage and to discover its secrets. in the present work which pours in the same direction, we decided to revive and explore a wealthy site located in rabat, the Moroccan capital, this site is named chellah, which represents the summing up of historical eras from the antiquity to the Islamic period and which is marked by the presence of antique and Islamic constructions which reflect this continuity. our research aims to build a model for the detection of areas that are not yet excavated but are already mentioned by archaeologists, geographers, and historians to validate their hypothesis and to find out where exactly these areas are located. our methodology is based on the processing of unmanned aerial vehicle (uav) images to generate high-resolution photogrammetric products with low cost, those datasets will be analyzed with a technique that has been in use since the '80s and which is using crop, soil, and shadow marks visualized on images taken by aerial photography. this analysis gave us the vision to select the zones on which a geophysical investigation by electrical tomography was carried out to approve the presence of the archeological components that require future excavation. our study focused on the importance of non-invasive methodologies for the study, preservation, and valorization of archaeological sites.
Measurement of the effective mean-free-path of the solar wind protons
Authors: Coburn Jesse , Chen Christopher , Squire Jonathan
Published: March 2021

The solar corona is heated and accelerated sufficiently to escape the gravitational bound of the sun into the interplanetary medium as a super-Alfvénic turbulent plasma called the solar wind. The Spitzer-Härm particle mean-free-path and relaxation time (i.e. to an isotropic Maxwellian distribution function) for typical solar wind proton parameters are large compared to the system size and therefore a non-collisional treatment of the plasma can be argued to be appropriate. Despite the long mean-free-path, large scales of the solar wind are fluid-like: density-pressure polarizations follow a polytropic equation of state. These observations suggest effective collisional processes (e.g. quasi-linear relaxation, plasma wave echo) are active, altering the equation of state from a non-collisional (or kinetic) to a polytropic equation of state (e.g. fluid magnetohydrodynamics [MHD]). We employ 13 years of high cadence onboard 0th-2nd moments of the proton velocity distribution function recorded by the Wind spacecraft to study the equation of state via compressive fluctuations. Upon comparison with a collisional kinetic-MHD dispersion relation solver, our analysis indicates an effective mean-free-path (collision frequency) that is [∼102] smaller (larger) than the typical Spitzer-Härm estimate. This effect is scale dependent justifying a fluid approach to large scales which breaks down at smaller scales where a more complex equation of state is necessary.
Modelling of Io’s Atmosphere for the IVO Mission
Authors: Wurz Peter , Vorburger Audrey , McEwen Alfred , Mandt Kathy , Davies Ashley , Hörst Sarah , Thomas Nicolas
Published: March 2021

The Io Volcano Observer (IVO) is a proposed NASA Discovery-class mission (currently in Phase A), that would launch in early 2029, arrive at  Jupiter in the early 2033, and perform ten flybys of Io while in Jupiter's orbit. IVO's mission motto is to 'follow the heat', shedding light onto tidal heating as a fundamental planetary process. Specifically, IVO will determine (i) how and where heat is generated in Io's interior, (ii) how heat is transported to the surface, and (iii) how Io has evolved with time. The answers to these questions will fill fundamental gaps in the current understanding of the evolution and habitability of many worlds across our Solar System and beyond where tidal heating plays a key role, and will give us insight into how early Earth, Moon, and Mars may have worked.

One of the five key science questions IVO will be addressing is determining Io's mass loss via atmospheric escape. Understanding Io's mass loss today will offer information on how the chemistry of Io has been altered from its initial state and would provide useful clues on how atmospheres on other bodies have evolved over time. IVO plans on measuring Io's mass loss in situ with the Ion and Neutral Mass Spectrometer (INMS), a successor to the instrument currently being built for the JUpiter Icy moons Explorer (JUICE). INMS will measure neutrals and ions in the mass range 1 – 300 u, with a mass resolution (M/ΔM) of 500, a dynamic range of > 105, a detection threshold of 100 cm–3 for an integration time of 5 s, and a cadence of 0.5 – 300 s per spectrum.

In preparation for IVO, we model atmospheric density profiles of species known and expected to be present on Io's surface from both measurements and previous modelling efforts. Based on the IVO mission design, we present three different measurement scenarios for INMS we expect to encounter at Io based on the planned flybys: (i) a purely sublimated atmosphere, (ii) the 'hot' atmosphere generated by lava fields, and (iii) the plume gases resulting from volcanic activity. We calculate the expected mass spectra to be recorded by INMS during these flybys for these atmospheric scenarios.
The timescale of the aseismic to seismic deformation in a cooling pluton: 40Ar-39Ar ages of the solid-state deformation in the Adamello (Southern Italian Alps)
Authors: Mittempergher Silvia , Zanchetta Stefano , Caldiroli Federico , Bistacchi Andrea , Zanchi Andrea , Villa Igor Maria
Published: March 2021

The northern Adamello is crosscut by ductile shear zones and pseudotachylyte-bearing faults, both compatible with the same stress field, with ductile shear zones crosscut by brittle faults. These relations are coherent with the re-equilibration of the pluton-related thermal anomaly to temperatures typical of the base of the seismogenic continental crust (T = 250 – 300°). Our new 40Ar-39Ar ages help to constrain the absolute age and duration of each deformation phase.

Samples included wall-rock biotite, bulk ultramylonites and pseudotchylytes. Before stepwise heating 40Ar-39Ar measurements, samples were characterized by microstructural, geochemical and petrological analyses.

The wall-rock biotite is 33.4±0.1 Ma old, independently of grainsize. Mylonites feature complex age spectra between 28-31 Ma, including biotite and altered feldspar. Four pseudotachylyte matrices are clustered around 30-31.5 Ma, and two samples have 25-26 Ma ages.

Ductile shearing active 2 Ma after wall-rock emplacement indicates either low strain rates, or a long-lasting thermal anomaly, which might be due to high emplacement depth, and/or the progressive assemblage of adjacent plutons through small magma pulses. Seismogenic faulting overlaps with mylonitization around 31 Ma; younger pseudotachylyte ages may be due to late-stage reactivation.
Future changes in snow and its influence on seasonal runoff and low flows in Czechia
Authors: Jenicek Michal , Hnilica Jan , Nedelcev Ondrej , Sipek Vaclav
Published: March 2021

Mountains are often called as “water towers” because they substantially affect hydrology of downstream areas. However, snow storages are decreasing and snow melts earlier mainly due to air temperature increase. These changes largely affect seasonal runoff distribution, including summer low flows and thus influence the water availability. Therefore, it is important to investigate the future change in relation between snow and summer low flows, specifically to assess a wide range of hydrological responses to different climate predictions. Therefore, the main objectives of this study were 1) to simulate the future changes in snow storages for a large set of mountain catchments representing different elevations and to 2) analyse how the changes in snow storages will affect streamflow seasonality and low flows in the future reflecting a wide range of climate predictions. The predictions of the future climate from EURO-CORDEX experiment for 59 mountain catchments in Czechia were considered. These data were further used to drive a bucket-type catchment model, HBV-light, to simulate individual components of the rainfall-runoff process for the reference period and three future periods.

Future simulations showed a dramatic decrease in snow-related variables for all catchments at all elevations. For example, annual maximum SWE decreased by 30%-70% until the end of the 21st century compared to the current climate. Additionally, the snow will melt on average by 3-4 weeks earlier in the future. The results also showed the large variability between individual climate chains and indicated that the increase in air temperature causing the decrease in snowfall might be partly compensated by the increase in winter precipitation. Expected changes in snowpack will cause by a month earlier period with highest streamflow during melting season in addition to lower spring runoff volume due to lower snowmelt inputs. The future climate scenarios leading to overall dry conditions in summer are associated with both lowest summer precipitation and seasonal snowpack. The expected lower snow storages might therefore contribute to more extreme low flow periods. The results also showed considerably smaller changes for the RCP 2.6 scenario compared to the RCP 4.5 and RCP 8.5 both in terms snow storages and seasonal runoff. The results are therefore important for mitigation and adaptation strategy related to climate change impacts in mountain regions.
Dynamics of the tongue of ionizations during the geomagnetic storm on September 7, 2015
Authors: Zhang Kedeng , Wang Hui , Liu Jing , Zheng Zhichao , He Yangfan , Gao Jie , Sun Luyuan , Zheng Yunfang
Published: March 2021

The dynamic evolution of the double tongue of ionization (TOI) into a single TOI at 400 km during the geomagnetic storm on September 7, 2015 was studied using the Defense Meteorological Satellite Program observations and Thermosphere Ionosphere Electrodynamic General Circulation model simulations. The double TOIs occurred in the presence of increased southward Bz and weak positive By, while the single TOI occurred in the presence of northward turning of Bz and duskward turning of By. In both double and single TOI events, the plasma at middle latitudes in the afternoon (prenoon) sector was greatly enhanced due to the local upward (upward) and zonal (meridional) E × B. The transition process is due to both the northward and duskward turning of IMF. The northward turning of IMF Bz weakens the SED and the TOI in both afternoon and morning sectors, while the increasing duskward IMF By strengthens the morning TOI.