bluuebunny/crossref_metadata_2025 huggingface dataset:
The impact of a warm moist air intrusion on dynamic and thermodynamic sea ice tendencies in the Arctic.
Authors: Dekker Evelien
Published: March 2020

Atmospheric blocking events in the Northern Hemishpere have been related to regional Arctic sea ice decline. During blocking events, pulses of warm and moist air enhance the radiative forcing on the sea ice in winter due to the increased longwave radiation associated with clouds. Several studies have shown that such events are related to regional sea ice concentration decline. Daily sea ice output with the latest version of CICE from the coupled Regional Arctic System model is used to study sea ice tendencies during January-February 2014. In this period there was a follow-up of a Atlantic warm moist air insturion and a Pacific warm moist air intrusion associated with surface air temperature perturbations up to 20 degrees locally.

A decline in sea ice concentration during wintertime does not neccesarily mean that ice melt has occurred. The goal of this case study is to distinguish the sea ice response between a dynamic and a thermodynamic component. In this way, we learn how much of the sea ice is advected into another region during such an event and how much the sea ice is lost due to the enhanced forcing and temperature increase.

 

 

 
A Method for Bias Correction of Remotely Sensed Precipitation across Western Ghats Region of India
Authors: Kunnath-Poovakka Aiswarya , T Iype Eldho
Published: March 2020

The systematic and random errors in different remotely sensed (RS) precipitation products varies spatially and seasonally.  Error characterisation of the satellite precipitation products is vital for improved hydrologic and climatic modelling as precipitation is the key component of surface and subsurface hydrologic system. In this study, a new approach is developed for the bias correction of different satellite and processed rainfall products across Western Ghats region of India. The Western Ghats are mountainous ranges of about 1600 Kms length parallel to west coast of peninsular India, which consists the largest tropical rainforest in India.  Many studies have reported that most of the RS rainfall products are underestimated in Western Ghats region. In the present study, a multiplicative error distribution model for the entire Western Ghats for each of the RS precipitation products used is developed. Quality controlled interpolated gridded rain gauge data from Indian Meteorological Department (IMD) is used as the base. The IMD rainfall data is cross validated with available rain gauge data in the Western Ghats region. The bias correction of four multisatellite high-resolution precipitation products namely, Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN), Tropical Rainfall Measuring Mission (TRMM) Multisatellite Precipitation Analysis (TMPA) precipitation products, 3B42 version 7 and TMPA-3B42RT (Real Time) version 7 and Precipitation data from NASA (National Aeronautics and Space Administration) Modern-Era Retrospective Analysis for Research and Applications (MERRA) is performed in this study. The multiplicative monthly bias factor for each grid cell of Western Ghats is generated with the IMD rainfall as reference and it is found that the monthly multiplicative error for Western Ghats fluctuates around a common mean for each of the grid cell. Based on this a rainfall multiplicative error distribution is generated for each month for the Western Ghats regions. Systematic errors in rainfall were corrected using this distribution and the efficacy of error-corrected rainfall is evaluated with the help of conceptual rainfall-runoff models. The results depict that the proposed method helps to reduce the bias in different rainfall products and provide improved runoff estimations at Western Ghats.
Creation of a new global geomorphological catalog of Mercury’s craters based on the latest MESSENGER data
Authors: Kolenkina Maria , Zharkova Anastasia , Feoktistova Ekaterina , Rodionova Zhanna , Kokhanov Alexander
Published: March 2020

Catalogs of impact craters – not only a layers of objects in GIS but complete databases containing the morphometric and geomorphological characteristics – can help to solve such fundamental problems as the estimation of parameters of populations of impactors that collided with the surface of the planet throughout its history, as well as to clarify the processes of crater formation in the Solar System.

Currently, there are few global catalogues of Mercury that includes big craters only. For example: 1) global digital GIS-catalogue of Mercury’s craters created by the Braun University, USA. It is based on modern data gathered by MESSENGER and, along with approximately 9000 objects; it includes coordinates and diameters of large craters (> 20 km), exclusively. At the same time, it doesn’t contain any geomorphological information; 2) the other source is a geomorphological catalogue that was composed by Sternberg Astronomical Institute (SAI), which, while containing geomorphological information, was created in accordance to data of Mariner 10 and was presented as a text in a table. The SAI’s catalogue includes craters with a size of 10 km and larger. 

Creation of a new global catalog of Mercury’s craters based on the latest MESSENGER data is a comprehensive work. The catalog will consist of two subdirectories: 1) the geomorphological catalog of craters with a size of 10 km and larger; 2) the morphometric catalog of craters with a size less than 10 km. We use MESSENGER MDIS global mosaic of Mercury with resolution ~166 m/pixel and several MESSENGER DEMs – the first global Mercury DEM with resolution 665 m/pixel and four DEMs on Mercury quadrants with resolution ~222 m/pixel (which will be used for formation of a database of craters with diameters less than 10 km).

In addition to the required elements of any catalog (coordinates of craters and their diameters), we will be able to add full geomorphological description of craters, reduced to code designations (to simplify the implementation of the catalog in the GIS) and morphometric characteristics. For instance: 1) the diameter of the interior feature (flat floor, central peak, or inner ring); 2) depth and relative depth of each crater; 3) max and min slopes; 4) the average level of inclination of the external; 5) internal slopes of crater; 6) the ratio of volume of the crater rim to the volume of the bowl. The most of listed parameters can be calculated both for craters and for the surrounding surface.

By using this catalog, we will be able to quickly get statistics and create thematic maps, for example, maps of crater density on regions of interest.

This research was supported by Russian Foundation for Basic Research (RFBR), project No 20-35-70019.
Low-cost, high accuracy Global Navigation Satellite System positioning for understanding floods
Authors: Winsemius Hessel , Krietemeyer Andreas , Van Dongen Kirsten , Gayton Ivan , Annor Frank , Tiberius Christiaan , Ten Veldhuis Marie-Claire , Samboko Hubert , Hut Rolf , Van de Giesen Nick
Published: March 2020

Detailed elevation is a prerequisite for many hydrological applications. To name a few, understanding of urban and rural flood hazard and risk; understanding floodplain geometries and conveyance; and monitoring morphological changes. The accuracy of traditional Global Navigation Satellite System (GNSS) chipsets in smart phones is typically in the order of several meters, too low to be useful for such applications. Structure from Motion photogrammetry methods or Light Detection and Ranging (LIDAR), may be used to establish 3D point clouds from drone photos or lidar instrumentation, but even these require very accurate Ground Control Point (GCP) observations for a satisfactory result. These can be acquired through specialised GNSS rover equipment, combined with a multi-frequency GNSS base station or base station network, providing a Real-Time (RTK) or Post-Processing Kinematics (PPK) solution. These techniques are too expensive and too difficult to maintain for use within low resource settings and are usually deployed by experts or specialised firms.

Here we investigate if accurate positioning (horizontal and vertical) can be acquired using a very recently released low-cost multi-constellation dual-frequency receiver (ublox ZED-F9P), connected with a simple antenna and a smart phone. The setup is remarkably small and easy to carry into the field. Using a geodetic (high-grade) GNSS antenna and receiver as base station, initial results over baselines in the order of a few km with the low-cost receiver revealed a positioning performance in the centimeter domain. Currently, we are testing the solution using a smart phone setup as base station within Dar es Salaam, to improve elevation mapping within the community mapping project “Ramani Huria”. We will also test the equipment for use in GCP observations within the ZAMSECUR project in Zambia and TWIGA project in Ghana. This new technology opens doors to affordable and robust observations of positions and elevation in low resource settings.
Plants possibility to control soil gas exchanges via mucilage
Authors: Haupenthal Adrian , Bentz Jonas , Brax Mathilde , Schuetzenmeister Klaus , Jungkunst Hermann , Kroener Eva
Published: March 2020

Gaseous matter exchanges in soil are determined by the connectivity of the pore system which is easily clogged by fresh root exudates. However, it remains unclear how a hydrogel (e.g. mucilage) affects soil pore tortuosity when drying. The aim of this study is to obtain a better understanding of gas diffusion processes in the rhizosphere by explaining patterns formed by drying mucilage.

We measured oxygen diffusion through a soil-mucilage mixture after drying using a diffusion chamber experiment. Therefore we mixed soil with different particle size with various amounts of mucilage. Afterwards we saturated the soil and measured the gas diffusion coefficient during drying.

We found that mucilage decreases gas diffusion coefficient in dry soil without significantly altering bulk density and porosity. Electron microscopy indicate that during drying mucilage forms filaments and interconnected structures throughout the pore space. Exudation of mucilage may be a plant possibility to actively alter gas diffusion in soil.
A theory of palaeoclimate reconstruction
Authors: Liu Mengmeng , Prentice Iain Colin , Braak Cajo ter , Harrison Sandy
Published: March 2020

Past climate states can be used to test climate models for present-day changes and future responses. Past states can be reconstructed from fossil assemblages, and WA-PLS (weighted averaging–partial least squares) is one of the most widely used statistical methods to do this. However, WA-PLS has a marked bias. Whatever biotic indicator is being used, reconstructed climate values are artificially compressed and biased towards the centre of the range used for calibration.

Here we developed an improvement of the method, derived rigorously from theory. It makes three assumptions:

a) the theoretical abundance of each taxon follows a Gaussian (unimodal) curve with respect to each climate variable considered;

b) the abundances of taxa are compositional data, so they sum to unity and follow a multinomial distribution;

c) the best estimate of the climate value at the site to be reconstructed maximizes the log-likelihood function – in other words, it minimizes the difference between theoretical and actual abundances as assessed by the likelihood criterion.

The best estimate of the climate value is approximated by a tolerance-weighted version of the weighted average in which the abundances of taxa are weighted by the inverse square of their tolerances (a measure of the range of environments in which a taxon is found). WA-PLS thus corresponds to the special case when all taxon tolerances are equal. The fact that this special case is far from reality generally is part of the the cause of the “compression and bias”. The new method can be applied using the existing functions for WA-PLS in the R package rioja. We show that it greatly reduces the compression bias in reconstructions based on a large modern pollen data set from Europe, northern Eurasia and the Middle East.
Microplastic input in to alluvial meadows of the Rhine river in Cologne, Germany
Authors: Müller Katharina Luise , Laermanns Hannes , Rolf Markus , Steininger Florian , Löder Martin , Möller Julia , Bogner Christina
Published: March 2020

River systems are major pathways for the transport of microplastic (MP). The Rhine is among the biggest river systems in regard to catchment size and discharge in northwestern Europe. Studies have documented the presence of MP in the Rhine and its tributaries along its course through Germany. The region of Cologne is densely populated, with a variety of land use forms occurring. Thus, an understanding of the presence and entry pathways of MP into alluvial meadows of the Rhine is important for risk assessments. 

This study aims to quantitively analyse transport pathways and sedimentation of MP into the alluvial meadows of the Rhine. We expect that the main entrance pathway of MP into these alluvial meadow soils is via fluvial transport. Two study sites were chosen in Cologne, one in the southern part of the central city (Poller Wiesen) and one in northern rural areas of the city (Merkenich-Langel). These sites were chosen as there are no agricultural fields in the direct vicinity, which could account for major MP input through surface runoff. The sites were flooded intermittently in the past with records of the water level during flooding and extent of flooded areas. For each site, sampling transects were chosen increasing in elevation and distance relative to the river water level. Samples were investigated for their MP concentrations via FTIR-spectroscopy. A digital elevation model supports the understanding of the water flow during flood events. Differences in MP concentrations with increasing elevation and distance to the river are thought to be caused by differences in intensity and frequency of flooding.

 
Effects of clay type on soil hydraulic and mechanical properties - a global perspective
Authors: Lehmann Peter , Leshchinsky Ben , Mirus Ben , Lu Ning , Gupta Surya , Or Dani
Published: March 2020

Clay fraction affects soil hydraulic and mechanical properties and dominates specific surface area. Clay fraction is used for soil classification and in pedotransfer functions (PTFs) to estimate soil hydraulic functions from simpler soil properties (texture). Remarkably, despite large variations in composition and properties of clay minerals, PTFs use this attribute in undifferentiated manner, applied similarly to soils in the tropics dominated by Kaolinite and temperate soils with Montmorillonite. The large specific surface area of Montmorillonite compared to Kaolinite reduces both the soil hydraulic conductivity and the residual friction angle. We develop PTFs informed by clay-type via soil specific surface area effects on saturated hydraulic conductivity and residual friction angle. For friction angle, PTFs were fitted to experimental data using information on clay content and clay type. For hydraulic conductivity, analytical models based on surface area and particle size were adapted to capture conductivity data from different climatic regions. Global distributions of clay types are used to map soil specific surface area and related hydro-mechanical properties to improve land-surface models (especially in the tropics) and refine natural hazard risk assessment (landslides and debris flows).
Mapping (un)certainty of machine learning-based spatial prediction models based on predictor space distances
Authors: Meyer Hanna , Pebesma Edzer
Published: March 2020

Spatial mapping is an important task in environmental science to reveal spatial patterns and changes of the environment. In this context predictive modelling using flexible machine learning algorithms has become very popular. However, looking at the diversity of modelled (global) maps of environmental variables, there might be increasingly the impression that machine learning is a magic tool to map everything. Recently, the reliability of such maps have been increasingly questioned, calling for a reliable quantification of uncertainties.

Though spatial (cross-)validation allows giving a general error estimate for the predictions, models are usually applied to make predictions for a much larger area or might even be transferred to make predictions for an area where they were not trained on. But by making predictions on heterogeneous landscapes, there will be areas that feature environmental properties that have not been observed in the training data and hence not learned by the algorithm. This is problematic as most machine learning algorithms are weak in extrapolations and can only make reliable predictions for environments with conditions the model has knowledge about. Hence predictions for environmental conditions that differ significantly from the training data have to be considered as uncertain.

To approach this problem, we suggest a measure of uncertainty that allows identifying locations where predictions should be regarded with care. The proposed uncertainty measure is based on distances to the training data in the multidimensional predictor variable space. However, distances are not equally relevant within the feature space but some variables are more important than others in the machine learning model and hence are mainly responsible for prediction patterns. Therefore, we weight the distances by the model-derived importance of the predictors. 

As a case study we use a simulated area-wide response variable for Europe, bio-climatic variables as predictors, as well as simulated field samples. Random Forest is applied as algorithm to predict the simulated response. The model is then used to make predictions for entire Europe. We then calculate the corresponding uncertainty and compare it to the area-wide true prediction error. The results show that the uncertainty map reflects the patterns in the true error very well and considerably outperforms ensemble-based standard deviations of predictions as indicator for uncertainty.

The resulting map of uncertainty gives valuable insights into spatial patterns of prediction uncertainty which is important when the predictions are used as a baseline for decision making or subsequent environmental modelling. Hence, we suggest that a map of distance-based uncertainty should be given in addition to prediction maps.
Research and Development of Universal Equipment for Geological Hazard Monitoring and Early Warning
Authors: Ma Juan , Zhang Mingzhi , Qi Gan , Xing Gloria , Huang Zack
Published: March 2020

Hilly and mountainous areas account for 65% of the total land area in China. There were 286,708 potential geological hazard sites registered at the end of 2018, among which 276,600 were small-and medium-sized. Small and medium geological hazards are a priority in geological disaster prevention. However, due to their large number and the high prices of professional monitoring equipment, it is difficult to find a cost-effective and accurate monitoring technology, method, or means for their long-term disaster monitoring. To this end, this paper aims to explore a reliable, cost-effective, precise, easily installable, low-power solution for small and medium geological hazard monitoring and early warning, centring on characteristic quantities such as deformation before collapse, landslides, and other disasters, and some key impact factors such as rainfall, moisture content, stress, and displacement velocity. Using universal  equipment based on microelectromechanical sensing technology and narrowband IoT technology, laboratory simulations and field tests were performed to research the equipment in terms of adaptation scenarios, effective monitoring ranges, installation methods and locations, and normalization of data reporting content, thus setting up a scientific method for small and medium geological hazard monitoring and early warning.
Stable water isotope observations during INTAROS cruises North of Svalbard: links to atmospheric circulation and sea ice processes
Authors: Touzeau Alexandra , Sodemann Harald , Sagen Hanne , Granskog Mats Anders , Raffel Bonnie , Roden Nicholas , Storheim Espen , de Lange Tor Einar , Chen Yi-Chun , Sandven Håkon
Published: March 2020

Water isotopes measured in ice cores are well-known tracers of paleoclimate variations. The ratio of heavy to light isotope in snow is indeed strongly controlled by the temperature during condensation along the entire airmass transport. This allows the utilization of isotope variability in the water cycle in current climatic conditions, and on weather time scales, to try to pinpoint key events and processes building up (or re-stating) the isotope signature of a given air mass. Because isotopic fractionation occurs every time water changes phase, it is highly beneficial to sample concurrently the different water reservoirs (i.e. seawater, sea ice, snow, rain and vapor) in order to truly understand the processes at work.

Here we present stable water isotope data from two cruises north of Svalbard within the INTAROS project (summer 2018 and summer 2019). During these cruises, vapor isotope composition was measured quasi-continuously on the coast guard icebreaker KV Svalbard. Seawater and precipitation samples were collected continuously throughout the cruises. The 2018 cruise mainly targeted locations within the Marginal Ice Zone north of Svalbard. On the 2019 cruise, sea ice samples and snow samples were collected at 8 ice stations, all the way to the North Pole. The liquid/solid samples were later analyzed at FARLAB at the University of Bergen.

A first analysis of the dataset shows that stable water isotope values vary with air mass origin, with marked differences between '18O-enriched’ air coming from the south-east (Barents Sea) and ‘18O-depleted’ air from the north-west (Inner Arctic) during the second cruise. During the 2019 cruise, vapor in air from the south-east tends to have relatively low d-excess values whereas precipitation is largely at equilibrium with the ambient vapor. This INTAROS dataset will be highly beneficial for studies using (coupled) isotope-enabled models, such as earth system models or high-latitude regional climate models, to validate their representation of the high-latitude water cycle.

 
Interseismic stress field variations in Hjalli-Ölfus, SW Iceland
Authors: Bjarnason Ingi Th. , Parameswaran Revathy M. , Thorbjarnardóttir Bergthóra S.
Published: March 2020

Western South Iceland Seismic Zone (SISZ) plate boundary lies adjacent to the Hengill central volcano. The sinistral SISZ connects the two arms of the divergent Mid-Atlantic Ridge (MAR) plate boundaries (Western and Eastern Volcanic Zones; WVZ, EVZ), while Hengill is a part of the WVZ. Seismicity in western SISZ, also known as the Hjalli-Ölfus region, closely interacts with the seismicity and magmatism in Hengill. For instance, the  4 June 1998 Mw 5.4 Hengill earthquake witnessed aftershocks that extended south to meet the Hjalli-Ölfus segment. This segment then hosted the Mw 5.1 Hjalli-Ölfus earthquake that occurred on 13 November 1998; elucidating the Hengill-Ölfus interaction. Relative relocations of earthquakes from July 1991 to December 1999 in Hjalli-Ölfus indicate that the seismogenic zone is predominant at 4-8 km depth, with 80% of the events occuring along an ~ENE-WSW trending seismic zone with lateral extension of ~12 km. The remaining occur along N-S faults, much like the observed norm of dextral faulting along the rest of the SISZ (e.g., 17 June 2000, 29 May 2008 earthquakes; Árnadottir et al., 2001; Brandsdottir et al., 2010). These relocated earthquake sequences were used to perform stress inversions within specified spatio-temporal grids. The results show that from 1994 to 1997, the western part of the Hjalli-Ölfus region exhibits an oblique normal stress regime, while the eastern part remains consistently strike-slip in nature. From mid-1997 to June 1998 western Hjalli-Ölfus shifts from an oblique normal to a strike-slip stress regime, while the eastern part maintains the strike-slip character of the SISZ. However, two months after the 4 June 1998 Hengill earthquake, the western part shifts back to an oblique normal regime, which loses a part of its normal-faulting tendency after the 13 November 1998 Hjalli-Ölfus earthquake. This variation in stress fields between two significant events on conjugately oriented prodominantly strike-slip faults is a clear example of these features influencing one another between seismic episodes. 
Paleomagnetic investigation of the Tarhanian deposits of Cop-Takyl section (Kerch peninsula, Crimea)
Authors: Filina Eugeniya , Pilipenko Olga , Rostovtseva Yuliana
Published: March 2020

With the goal to provide the new magnetostratigraphic investigations of the Miocene marine deposits of the Black Sea Basin the forty-four oriented hand blocks of the Cop-Takyl section (45°N, 36°E, Kerch peninsula, Crimea) were collected during summer 2019 field work. The section is composed mainly of clays, has a total thickness of ~ 53 m and covered the Tarhanian stratigraphic interval. Standard paleomagnetic measurements have been performed to establish a new magnetostratigraphic record for the Cop-Takyl section. The composition of the ferromagnetic fraction was examined using dependences of magnetic susceptibility on temperature and saturation magnetic moment on temperature. These thermo magnetic analyzes showed that the low concentration of magnetite is the main carrier of the natural remanent magnetization NRM. Coercivity of remanence Bcr values, determined from backfield demagnetization measurements, range between ~34 and 91 mT. The structure of the magnetite grains is mainly pseudo-single domain. In order to determine true NRM directions, we studied the anisotropy of magnetic susceptibility. The rock sample possesses a planar anisotropy, which is a characteristic of the normal sedimentary rocks. The alternating field demagnetization of the samples (three duplicates from each level) was used for obtaining NRM vector angle elements. Demagnetization results were analyzed using orthogonal plots and stereographic projections. Polarity components were isolated in most samples between 15-60 mT. The values of the declination D and inclination I of the NRM satisfactory agree for all three duplicates from each level. This allows to average angle elements and construct curves of I and D variations over the thickness of the section. New paleomagnetic data of the Cop-Takyl section will used for assessing the effect of astronomical cyclicity on sedimentation processes. This work was supported by Russian Science Foundation, project № 19-77-10075.
Does temperate agroforestry reduce nutrient leaching losses compared to cropland monocultures?
Authors: Schmidt Marcus , Corre Marife D. , Duan Xiaohong , Heinlein Florian , Veldkamp Edzo
Published: March 2020

Over the past decades, excessive use of fertilizers in cropland monocultures in combination with a decrease in fertilizer use efficiency, have led to an increase in nutrient leaching losses, especially for nitrate. Consequently, ground water pollution is widespread and starting to be recognized and potentially sanctioned by the European Union. Unfertilized tree rows alternating with crop rows (e.g. alley-cropping agroforestry) are hypothesized to act as a safety net by taking up excess nutrients below the crop-rooting zone. Here, we measured leaching losses of nitrogen (N), phosphorus (P) and potassium (K) during two growing seasons in agroforestry systems and adjacent monocultures at three sites in Germany, representing a wide range of soil characteristics. Leaching losses of N, P and K were generally lower under agroforestry tree rows at all sites compared to agroforestry crop rows or crop monocultures. Overall, agroforestry reduced nitrate leaching losses by up to 82% compared to monocultures, but showed comparable losses of P and K. Nutrient leaching losses were high in the agroforestry crop rows close to the tree rows where crop productivity is lowest due to resource competition with trees. An adjusted management, e.g. reduced fertilizer inputs close to the tree rows, may counteract these losses. Our results suggest that agroforestry has the potential to reduce nutrient leaching losses through the trees and the application of fertilizer should be reduced in the agroforestry crop row close to the trees. The reduction in nutrient leaching losses in agroforestry indicates an increase in the soil function of water filtration. In order to achieve large-scale implementation of temperate agroforestry, its environmental benefits need to be financially valued for farmers to adapt this widely applicable land use alternative. The presented project, SIGNAL (Sustainable intensification of agriculture through agroforestry) is part of the German research initiative BonaRes (Soil as a sustainable resource).
Modelling London’s Urban Green physiological responses and impacts on flood retention sustainability under climate change
Authors: Zhang Ziyan , Paschalis Athanasios , Mijic Ana
Published: March 2020

Surface water flooding is the most likely cause of flooding in London, still affecting at least 3% of the area and up to 680,000 properties. Urbanization and climate change are expected to increase the impacts of urban flooding in the near future. To mitigate such problem and provide resilient ecosystem services for Europe’s largest capital, Urban Green Infrastructure adaptations have been extensively used in the last two decades in conjunction with traditional grey infrastructure. Sustainability and efficiency of green infrastructure depend on the ability of plants to emulate the natural ecosystem water and carbon cycles in the city. Considering the expected rise in temperature, changes in rainfall patterns and intensification of the urban heat island effect, existing and planned green infrastructure solutions might be vulnerable to plant water stress. Since there will be much less space available to accommodate future changes in cities, it is extremely important to think about the system’s potential performance further ahead the construction. In this study we perform a detailed evaluation of representative London parks and rain gardens to mitigate flood risk under a changing climate. Specifically, we focus on the hydrological performance of urban raingardens (consisting exclusively of low stature plants) and urban parks (as a composite of low stature vegetation and urban forests) in London. The coupled water and carbon dynamics were evaluated using the ecohydrological model Tethys-Chloris (TeC) forced with the last generation climate change projections UKCP18. Based on our simulation we disentangle the composite effects of climate change, to plant physiological responses to elevated CO2 and changes in precipitation patterns and temperature.

Our results indicate that:

(a) Changes in weather severely affect plant efficiency during the 2nd half of the 21st century;

(b) Effectiveness of green infrastructure is strongly dependent on possible climate change outcomes;

(c) Within a certain range of plausible climate changes, for the 1st half of the 21st century positive effects of changes in climate can mostly counteract negative plant physiological responses to elevated CO2, but those negative effects gradually become dominant;

(d) Efficient and sustainable design of urban green infrastructure to mitigate flooding must consider an optimal adaptive choice of plants to offset the projected negative impacts of elevated CO2 and uncertain climate.
A comparison of two alternative approaches to modelling the sea ice floe size distribution.
Authors: Bateson Adam , Feltham Daniel , Schröder David , Hosekova Lucia , Ridley Jeff , Aksenov Yevgeny
Published: March 2020

Sea ice exists as individual units of ice called floes. These floes can vary by orders of magnitude in diameter over small spatial scales. They are better described by a floe size distribution (FSD) rather than by a single diameter. Observations of the FSD are frequently fitted to a power law with a negative exponent. Floe size can influence several sea ice processes including the lateral melt rate, momentum exchange between the sea ice, ocean and atmosphere, and sea ice rheology. There have been several recent efforts to develop a model of the floe size distribution to include within sea ice models to improve the representation of floe size beyond a fixed single value. Some of these involve significant approximations about the shape and variability of the distribution whereas others adopt a more prognostic approach that does not restrict the shape of the distribution.

In this study we compare the impacts of two alternative approaches to modelling the FSD within the CICE sea ice model. The first assumes floes follow a power law distribution with a constant exponent. Parameterisations of processes thought to influence the floe size distribution are expressed in terms of a variable FSD tracer. The second uses a prognostic floe size-thickness distribution. The sea ice area in individual floe size categories evolves independently such that the shape of distribution is an emergent behaviour rather than imposed. Here we compare the impact of the two modelling approaches on the thermodynamic evolution of the sea ice. We show that both predict an increase in lateral melt with a compensating reduction in basal melt. We find that the magnitude of this change is highly dependent on the form of the distribution for the smallest floes. We also explore the impact of both FSD models on the momentum exchange of the sea ice and find a large response in the spatial distribution of sea ice volume. Finally, we will discuss whether the results from the prognostic FSD model support the assumptions required to construct the power law derived FSD model.
Singular Extreme Events and Their Attribution to Climate Change: A Climate Service–Centered Analysis
Authors: Jezequel Aglae , Dépoues Vivian , Guillemot Hélène , Rajaud Amélie , Trolliet Mélodie , Vrac Mathieu , Vanderlinden Jean-Paul , Yiou Pascal
Published: March 2020

Extreme event attribution (EEA) proposes scientific diagnostics on whether and how a specific weather event is (or is not) different in the actual world from what it could have been in a world without climate change. This branch of climate science has developed to the point where European institutions are preparing the ground for an operational attribution service. In this context, the goal of this article is to explore a panorama of scientist perspectives on their motivations to undertake EEA studies. To do so, we rely on qualitative semi-structured interviews of climate scientists involved in EEA, on peer-reviewed social and climate literature discussing the usefulness of EEA, and on reports from the EUCLEIA project (European Climate and Weather Events: Interpretation and Attribution), which investigated the possibility of building an EEA service. We propose a classification of EEA’s potential uses and users and discuss each of them. We find that, first, there is a plurality of motivations and that individual scientists disagree on which one is most useful. Second, there is a lack of solid, empirical evidence to back up any of these motivations.
Characteristics of Nature-based Solutions in non-urban environments
Authors: Tuomenvirta Heikki , Korhonen Natalia , Votsis Athanasios , Menenti Massimo , Alfieri Silvia , Kumar Prashant , Renault Fabrice , Soini Katriina
Published: March 2020

Nature-based Solutions (NBS) are being developed in variable environments to address societal challenges with use of ecosystem services. Recently there has been notable activities and progress in developing and implementing NBS in urban environments. On the other hand, NBS have “roots” in nature conservation and ecosystem services. Accordingly, the International Union for Conservation of Nature is leading the community effort to articulate a Global Standard for the Design and Verification of Nature-based Solutions.

The ongoing EU H2020 project OPERANDUM focuses on development and implementation of NBS to mitigate exposure, vulnerabilities and risks to hydro-meteorological hazards in European rural and natural landscapes. This presentation identifies and examines some of the characteristic of NBS in non-urban settings based on literature and experiences gained in the OPERANDUM project. These include, e.g. physical environment, economic and social capital as well as other resources, and legal and governance issues. Additional challenges arise from requirement to co-design of NBS with the stakeholders which can have a large diversity of societal demands for land use. The OPERANDUM project activities are discussed in relation to four approaches relevant for the OPERANDUM project: Ecosystem-based disaster risk reduction; Climate adaptation services; Ecosystem-based adaptation; Ecosystem-based mitigation.

Case – studies are being developed to document the impact of extreme events related to different hydro-meteorological hazards, e.g. floods, landslides and droughts by combining earth observation with hydro-meteorological data. The analysis is designed to mirror the role of NBS in providing multiple benefits, in particular in mitigating impacts of extreme hydro-meterological events by acting on bio-geophysical and socio-economic variables characterizing exposure and vulnerabilities.
The Santa Rosa Meteorite from Colombia: An example of critical raw materials in a meteorite
Authors: Wilke Franziska D.H. , Bsdok Barbara , Altenberger Uwe , Concha Ana E.
Published: March 2020

Meteorites, especially the undifferentiated ones like primitive chondrites, provide information about the origin and initial conditions of the solar system since they contain presolar and solar nebula materials (Scott, 2007). Differentiated meteorites like iron meteorites play a distinct role in constraining the early phases of planetary accretion (Yang et al. 2007). They also provide the possibility to receive information about core properties and planetary bodies. In addition to the gain in such fundamental scientific knowledge both types are of interest for the exploration of critical and precious elements (CRMs).

In the future, the tremendous increase of the consumption of these elements from terrestrial deposits and the subsequent shortage could lead to an exploitation of extra-terrestrial deposits. Therefore, “space-mining” of near Earth objects could be used as alternative source of raw materials (Ross, 2001).

While improving the characterization and classification of the Santa Rosa de Viterbo Iron Meteorite, we found notable concentrations of Au and Ge alongside major elements such as Fe, Ni and Co in the bulk composition of that meteorite. Major and rock-forming minerals such as kamacite and taenite incorporate hundreds of ppm of Ge whereas schreibersite, itself a minor component in that particular meteorite, is a source for Au. In kamacite and taenite also Ir and Ga were found in minor amounts.

 

Scott, E. R. (2007). Chondrites and the protoplanetary disk. Annu. Rev. Earth Planet. Sci., 35, 577-620.

Ross, S. D. (2001). Near-earth asteroid mining. Space, 1-24.

Yang, J., Goldstein, J. I., & Scott, E. R. (2007). Iron meteorite evidence for early formation and catastrophic disruption of protoplanets. Nature, 446(7138), 888.

 
Modeling effects of plastic mulching on crop yields and water productivity in the middle Heihe River Basin
Authors: Zhang Wang , Zheng Chunmiao
Published: March 2020

Plastic mulching is an effective field practice to improve crop water productivity (WP), especially widely used in arid and semi-arid areas. The positive effects of soil mulching on crop yield and WP have been studied through numerous field experiments and simulations at the site scale. However, few studies have focused on the mulching effects at the regional scale. Zhangye oasis, a typical arid region in the middle Heihe River Basin, was chosen as the study area. Global sensitivity analysis was applied to determine the most sensitive parameters in AquaCrop model. Based on the results of global sensitivity analysis, soil and crop parameters of AquaCrop model were calibrated and validated using field observations from three stations. The normalized root mean square error (NRMSE) values for soil water content, seed maize canopy cover, aboveground biomass, yield, spring wheat canopy cover, aboveground biomass and yield were 18.7%, 6.7%, 23.5%, 12.5%, 10.7%, 24.2% and 15.0% during the calibration period, and the corresponding values during the validation period were 25.1%, 7.0%, 22.2%, 17.7%, 9.1%, 23.6% and 11.7%, respectively. These values indicated the calibrated model performed well to simulate the soil water content and crop growth. Compared with no-mulching, the average soil water content during the growth period, seed maize yield and WP under mulching had been increased by 8.8%, 3.0% and 3.0%, respectively. The results demonstrated that plastic mulching could effectively improve the yield and WP of seed maize, which not significantly on spring wheat. This study offers a quantitatively analysis for plastic mulching applications at the regional scale.
Sensing Ionospheric Turbulence Using GNSS
Authors: Tagliaferro Giulio , Gatti Andrea , Realini Eugenio
Published: March 2020

Electron density in ionospheric plasma exhibits fluctuations and irregularities in time and space, at several scales. Plasma, being ionized gas, is subject to a turbulent behaviour similar to that observed in fluid dynamics, with two main distinctions: a) its dynamics are coupled with electromagnetic fields; b) collisions of particles are rare. These unique properties characterize the inertial range of ionospheric plasma turbulence, which represents the energy cascade from large-scale structures (e.g. travelling ionospheric disturbances) to small-scale ones (eddies) until energy dissipation occurs. 

Kolmogorov power law would predict a spectrum of 8/3 and equivalently a structure function with a power law of 5/3 for a phase signal crossing a 3D turbulent medium. However, the previous investigation of spatial structure characteristic of the ionosphere using LOFAR array observed a power law of around 1.9 in the spatial domain. In this study, we investigate the spatio-temporal and temporal structure of the ionosphere using structure function of GNSS phase geometry free signals from both medium earth orbit satellites and geostationary ones. We found two regimes, one compatible the 5/3 Kolmogorov theory and one obeying a 2 power law. We propose an interpretation for the two regimes, the first being a 3D turbulent flow driven by local instabilities, and the second one being driven by solar radiation-induced ionization and successive recombination. The second spectrum obeys a power law of 2, that is the power spectrum of a sinusoidal function like the local sun elevation. By using receivers at almost constant solar irradiance located in polar regions, we further observe the turbulent regimes also in spatio-temporal structure function.
Secondary Organic Aerosol Reduced by Mixture of Atmospheric Vapours
Authors: Mentel Thomas , McFiggans Gordon , Wildt Jürgen , Kiendler-Scharr Astrid ,   JPAC-Team 2015
Published: March 2020

Biogenic volatile organic compounds (VOC) are important secondary organic aerosol (SOA) precursors. Whilst isoprene dominates VOC plant emissions globally, its yield of SOA mass is found to be modest in comparison to that of monoterpenes (MT). Tracers from isoprene oxidation have been observed in particles showing that they condense from the gas phase and yet new particle formation is suppressed by the presence of isoprene in mixtures of plant emissions containing MT.

Experiments were performed in the JPAC chamber in Jülich. We showed that isoprene can suppress both the instantaneous mass formation and overall yield of monoterpenes in mixtures by two effects: oxidant and product scavenging. Isoprene scavenged OH radicals from reacting with MT (oxidant scavenging). Subsequently, the resulting isoprene peroxy radicals reacted with highly oxygenated peroxy radicals from MT oxidation (product scavenging). These effects from isoprene, also demonstrated using CO or CH4, reduced the yield of low-volatility, highly oxygenated molecules (HOM) from MT that would otherwise form SOA.

Our results show that in mixtures changes in particle mass and number are not additive, and yields from single precursor experiments cannot simply be linearly combined. Reactive, modest SOA yield compounds are not necessarily net SOA producers and isoprene oxidation can suppress both SOA number and mass. Global model calculations support that OH scavenging and product scavenging can also operate in the real atmosphere. Our results highlight a need for more realistic consideration of SOA formation in the atmosphere analogous to the treatment of ozone formation, where interactions between the mechanistic pathways involving peroxy radicals are recognised to be essential.
Natural springs’ protection and probabilistic risk assessment under uncertain conditions
Authors: Bianchi Janetti Emanuela , Riva Monica , Guadagnini Alberto
Published: March 2020

We introduce, develop and test a novel Groundwater Probabilistic Risk Model, GPRM, aimed at assessing (and preventing) negative issues related to water resources management and exploitation. We apply GPRM to a highly heterogeneous regional field case, located in Northern Italy. Different risk pathways are presented formally forming a fault tree model, which enables identification of all basic events contributing to an (undesired) system failure. The latter is quantified in terms of depletion of a natural springs system representing a key feature of the considered groundwater system. The proposed GPRM allows to include the effect of multiple sources of uncertainty in our knowledge and description of the system on the evaluation of the overall probability of system failure due to different pumping schemes. In this context, we consider two probabilistic models based on different reconstruction of the aquifer geological structure. In each conceptual model, hydraulic conductivity associated with the geomaterials composing the aquifer and the boundary conditions are affected by uncertainty. Our results demonstrate that the application of GPRM to the field case allows (i) to quantify the risk associated with springs depletion due to increasing exploitation of the aquifer; (ii) to quantify how different sources of uncertainty (conceptual model uncertainty and model parameters’ uncertainty) affects this risk; (iii) to determine the optimal pumping scheme; and (iv) to identify the most vulnerable springs, where depletion first occurs.
Comminution effects on mineral grade distribution
Authors: Baldassarre Gabriele , Baietto Oliviero
Published: March 2020

Every mining operations is followed by a beneficiation process aimed to deliver quality material to the transformation industry. Mainly, in mineral processing comminution and grinding of extracted ore, are crucial operations for the following separation steps in order to obtain valuable minerals from gangue.

Comminution is the most energy consuming phase and the quality of the results is strictly related to the characteristic of the material under treatment.

A preliminary study has been performed in order to understand the crushing behaviour of a mixed sulphide ore, containing galena and sphalerite, and the distribution of the two target minerals among the different sized products of the process.

Ore samples have been examined and characterized by means of thin sections observation and SEM analyses for the determination of the free grain size, while XRD quantitative analyses have been performed for the definition of the grades.

The selected crushing circuit comprises lab-scale impact crusher, jaw crusher, disk mill and rod mill. For each stage of the process products below the free grain size threshold have been collected and particle size analyses have been carried out.

Comminution products were divided in dimensional classes suitable for flotation separation, ranging between 0.250 and 0.075mm and XRD analyses showed a variable mineral grade distribution varying with the reduction in dimension of the products.

This important trend should be considered for further investigation related to an efficient froth flotation separation.