bluuebunny/crossref_metadata_2025 huggingface dataset:
The Impacts of Water Quality Changes on Aquatic Ecosystems: A Case Study of Clariano River, Spain
Authors: Vagheei Hamed , Vezza Paolo , Palau-Salvador Guillermo , Boano Fulvio
Published: March 2020

The Impacts of Water Quality Changes on Aquatic Ecosystems: A Case Study of Clariano River, Spain

Hamed Vagheei1, Paolo Vezza2, Guillermo Palau-Salvador3, Fulvio Boano4

PhD Student, the Polytechnic University of Turin, hamed.vagheei@polito.it

Assistant professor, the Polytechnic University of Turin, paolo.vezza@polito.it

Associate Professor, the Polytechnic University of Valencia, guipasal@agf.upv.es

Associate Professor, the Polytechnic University of Turin, fulvio.boano@polito.it

Abstract

Water quality degradation resulting from different anthropogenic activities such as agriculture, deforestation and urbanization is a serious worldwide challenge which have negative impacts on aquatic ecology. Unfortunately, it is still difficult to quantitatively determine the impacts of water quality changes on aquatic communities. The objective of the present research activity is to investigate aquatic ecosystem responses to water quality deterioration using a case study of Clariano River, Spain. The Clariano River faces low water quality and the loss of biodiversity in some parts as a result of agricultural, industrial and livestock activities as well as wastewater treatment plants (WWTP) effluents entering the river. The Soil and Water Assessment Tool (SWAT), an eco-hydrological model, is used in the present study for the modelling of discharge, sediment and nutrients. SWAT-CUP is also used to calibrate and validate the SWAT model. We are currently employing the results from the calibrated model to obtain a better understanding of possible relations between water quality and biodiversity. In fact, the present study will focus on macroinvertebrates as biological indicators of stream health, and the model predictions will be coupled with empirical correlations between stream water quality and macroinvertebrates presence in order to assess the impacts of water quality changes on aquatic ecosystem. In addition, different model scenarios will be compared to explore the potential impacts of changes in land use, climate and WWTPs operation on the aquatic ecosystem.

Keywords: aquatic ecosystem, Clariano River, eco-hydrological modelling, water quality, water resources management
Pulsed terrestrial organic carbon persists in an estuarine environment after major storm events
Authors: Asmala Eero , Osburn Christopher , Paerl Ryan , Paerl Hans
Published: March 2020

The transport of dissolved organic carbon from land to ocean is a large and dynamic component of the global carbon cycle. Export of dissolved organic carbon from watersheds is largely controlled by hydrology, and is exacerbated by increasing major rainfall and storm events, causing pulses of terrestrial dissolved organic carbon (DOC) to be shunted through rivers downstream to estuaries. Despite this increasing trend, the fate of the pulsed terrestrial DOC in estuaries remains uncertain. Here we present DOC data from 1999 to 2017 in Neuse River Estuary (NC, USA) and analyze the effect of six tropical cyclones (TC) during that period on the quantity and fate of DOC in the estuary. We find that that TCs promote a considerable increase in DOC concentration near the river mouth at the entrance to the estuary, on average an increase of 200 µmol l-1 due to storms was observed. TC-induced increases in DOC are apparent throughout the estuary, and the duration of these elevated DOC concentrations ranges from one month at the river mouth to over six months in lower estuary. Our results suggest that despite the fast mineralization rates, the terrestrial DOC is processed only to a minor extent relative to the pulsed amount entering the estuary. We conclude that the vast quantity of organic carbon delivered to estuaries by TCs transform estuaries from active biogeochemical processing “reactors” of organic carbon to appear more like passive shunts due to the sheer amount of pulsed material rapidly flushed through the estuary.
Space-phase shifts acquiring by breathers after mutual collisions
Authors: Gelash Andrey
Published: March 2020

The key result of this work is the first theoretical computation of exact expressions describing space and phase shifts acquiring by breathes after mutual collisions in the framework of the focusing one-dimensional nonlinear Schrödinger equation (NLSE) model [1]. Similar expressions are the backbone of soliton theory, where they allow to predicts soliton interaction dynamics and introduce statistical description of soliton gas in terms of kinetic equation. Theory of breathers – solitary type wave groups on an unstable background – has been developing almost as long as theory of solitons. However, up to now, this important part of theory has been missing.

In our work we present space and phase shift formulas for the NLSE breathers and demonstrate how they can be used to go deeply in understanding of an intriguing nonlinear phenomena – formation rogue waves from a calm background. With these formulas we show that synchronized collisions of breathers are the central mechanism of extreme amplitude wave formation as a result of modulation instability development. We illustrate this conclusion by particular examples of multi-breather dynamics as well as by statistical analysis of multi-breather interactions. In comparison to the work [1], here we also analyse the impact of the effects lying beyond the NLSE model on the multi-breather synchronization. Finally, we present new scenarios of the synchronised multi-breather interactions, that can be observed in laboratory experiments.

The work was supported by the RFBR grant No. 19-31-60028.

[1] A. A. Gelash, Formation of rogue waves from a locally perturbed condensate, Phys. Rev. E 97, 022208 (2018).
Machine learning approach for multi-perspective volcanic eruption recognition using thermal infrared images
Authors: Corradino Claudia , Ganci Gaetana , Bilotta Giuseppe , Cappello Annalisa , Del Negro Ciro
Published: March 2020

Detect, locate and characterize eruptions in real-time is fundamental to monitor volcanic activity. Here we present an automatic system able to discover and identify the main types of eruptive activities by exploiting infrared images acquired by the thermal cameras installed around Mount Etna volcano. The system, which employs the machine learning approach, is based on a decision tree tool and a bag of words-based classifier. The decision tree provides information on the visibility level of the monitored area, while the bag of words-based classifiers detects the onset of the eruptive activity and recognize the eruption type among either explosion and/or lava flow or plume. Thus, applied to each image of all thermal cameras over Etna in real-time, the proposed system provides two outputs, namely the visibility level and the recognized activity status. By merging the outcomes coming from each thermal camera, the monitored phenomena can be fully described from different perspectives getting deeper information in real-time and in an automatic way.   
The observed recent surface air temperature development across Svalbard and concurring footprints in local sea ice cover
Authors: Dahlke Sandro , Hughes Nicholas , Wagner Penelope , Gerland Sebastian , Wawrzyniak Tomasz , Ivanov Boris , Maturilli Marion
Published: March 2020

The Svalbard archipelago in the Arctic North Atlantic is experiencing rapid changes in the surface climate and sea ice distribution, with impacts for the coupled climate system and the local society. Using observational data of surface air temperature (SAT) from 1980–2016 across the whole Svalbard archipelago, and sea ice extent (SIE) from operational sea ice charts,  a systematic assessment of climatologies, long-term changes and regional differences is conducted. The proximity to the warm water mass of the West Spitsbergen Current (WSC) drives a markedly warmer climate in the western coastal regions compared to northern and eastern Svalbard. This imprints on the SIE climatology in southern and western Svalbard, where the annual maxima of 50–60% area ice coverage are substantially less than 80–90% in the northern and eastern fjords. Owing to winter-amplified warming, the local climate is shifting towards more maritime conditions, and SIE reductions of between 5% to 20% per decade in particular regions are found, such that a number of fjords in the west have been virtually ice-free in recent winters. The strongest decline comes along with SAT forcing and occurs over the most recent 1–2 decades in all regions. In the 1980s and 1990s, enhanced northerly winds and sea ice drift can explain 30–50% of SIE variability around northern Svalbard, where they had correspondingly lead to a SIE increase. At the same time, interannual temperature fluctuations within the WSC waters can explain 20-37% of SIE variability in a number of fjords on the west coast. With an ongoing warming it is suggested that both the meteorological and cryospheric conditions in eastern Svalbard will become increasingly similar to what is already observed in the western fjords, namely suppressed typical Arctic climate conditions.
Porosity channeling and fracturing in fluid over-pressure zones
Authors: Koehn Daniel , Piazolo Sandra , Sachau Till , Toussaint Renaud
Published: March 2020

It is important to understand the effects of fluid over-pressure in rocks because gradients in over-pressure can lead to failure of rocks and expulsion of fluids. Examples are hydro-fracturing in engineering as well as fluid generation during hydrocarbon maturation, metamorphic reactions or over-pressure below seals in sedimentary basins. In order to have an understanding of the complexity of effective stress fields, fracture, failure and fluid drainage the process was studied with a dynamic hydro-mechanical numerical model. The evolution of fluid pressure build up, fracturing and the dynamic interaction between solid and fluid is modeled. Three scenarios are studied: fluid pressure build up in a sedimentary basin, in a confined zone and in a horizontal layer that is offset by a fault. Results indicate that the geometry of the fluid-overpressure zone has a first order control on the patterns including porosity evolution and fracturing. If the over-pressure develops below a seal in a sedimentary basin, the effective differential and mean stress approach zero and the horizontal and vertical effective stresses flip in orientation leading to horizontal hydro-factures or breccia zones. If the over-pressure zone is confined vertically as well, the standard effective stress model develops with the effective mean stress decreasing while the differential stress remains mainly constant. This leads to semi-vertically aligned extensional and conjugate shear failure at much lower over-pressures than in the sedimentary basin. A perfectly aligned horizontal layer that increases in fluid pressure internally leads to a horizontal hydro-fracture within the layer. A faulted layer develops complex multi-directional failure with the fault itself being a location of early fracturing followed by brecciation of the layer itself. All simulations undergo a phase transition in porosity evolution with an initially random porosity reducing its symmetry and forming a static porosity wave with an internal dilation zone and the development of dynamic porosity channels within this zone that drain the over-pressure. Our results show that patterns of fractures, hence fluid release, that form due to high fluid overpressures can only be successfully predicted if the geometry of the geological system is known, including the fluid overpressure source and the position of seals and faults that offset source layers and seals.
The European Ecotron of Montpellier: experimental platforms to study ecosystem response to climate change
Authors: Sauze Joana , Roy Jacques , Piel Clément , Landais Damien , Gritti Emmanuel S , Ravel Olivier , Lemoine Hélène , Faez Abdelaziz , Devidal Sébastien , Milcu Alexandru
Published: March 2020

The sustainability of agricultural, forested and other managed or natural ecosystems is critical for the future of mankind. However, the services provided by these ecosystems are under threat due to climate change, loss of biodiversity, and land use changes. In order to face the challenges of preserving or improving ecosystems services and securing food supply we need to understand and forecast how ecosystems will respond to current and future changes. To help answer those questions Ecotrons facilities are born. Such infrastructures provide sets of confinement units for the manipulation of environmental conditions and real-time measurement of ecological processes under controlled and reproduceable conditions, bridging the gap between the complexity of in natura studies and the simplicity of laboratory experiments.

The European Ecotron of Montpellier (www.ecotron.cnrs.fr) is an experimental research infrastructure for the study of the impact of climate change on ecosystem functioning and biodiversity. This infrastructure offers, through calls open to the international community, three experimental platforms at different scales. The Macrocosms platform is composed of twelve 40 m3 units, each able to host 2-12 t lysimeters, with a 2-5 m² canopy area and a soil depth of up to 2 m. The Mesocosms one has eighteen 2-4 m3 units, each able to host lysimeters of 0.4-1 m depth and 0.4-1 m² area. The Microcosms platform consists of growth chambers (1 m height, 1 m² area) in which smaller units (with photosynthetic plants, soils, insects, etc.) can be installed. Each experimental unit of each platform allows to confine terrestrial ecosystems. This way, environmental parameters such as temperature (-10 to +50 °C), relative humidity (20-80 %), precipitation (sprinkler or drip) and atmospheric CO2 concentration (200-1000 ppm) are strictly and continuously controlled and recorded. But the uniqueness of the European Ecotron of Montpellier lies on its ability to also continuously measure, in each unit, net gas exchange (evapotranspiration, CO2 / CH4 / N2O net fluxes) that occur in between the ecosystem studied and the atmosphere, as well as CO2, H2O, N2O and O2 isotopologues. Those tools are powerful and remarkable to access additional information about processus involved in ecosystem functioning.

The aim of this presentation is to describe the Macrocosms and the Mesocosms platforms through examples of international projects recently run in these platforms.
Colloidal iron and organic carbon control soil aggregate formation and stability
Authors: Wang Liming , Krause Lars , Klumpp Erwin , Nofz Ines , Missong Anna , Amelung Wulf , Siebers Nina
Published: March 2020

Several beneficial soil functions are linked to aggregates, but how the formation and stability depend on the presence of colloidal building blocks is still understood poorly. Here, we sampled subsites from an arable toposequence with 190 and 340 g kg-1 clay, and isolated small soil microaggregates (small SMA; < 20 µm) from larger macroaggregate units (> 250 µm) using an ultrasonic dispersion energy of 60, 250, and 440 J mL-1 , respectively. We then allowed these small SMA to reaggregate after chemical removal of organic carbon (OC) as well as of Fe- and Al (hydr)oxides, respectively. The size distribution of the reaggregated small SMA and fine colloids (< 0.45 µm) was analyzed via laser diffraction and asymmetric flow field-flow fractionation coupled to inductively coupled plasma mass spectrometry and OC detection, respectively. We found elevated amount of both fine colloids and stable SMA at subsites with larger clay contents. The size distribution of small SMA was composed of two distinct fractions including colloids (< 1 µm) and SMA with an average size of 5 µm. The removal of Fe with Dithionite-Citrate-Bicarbonate (DCB) shifted the size of the small SMA to a larger equivalent diameter, while destruction of OC with NaOCl reduced it. After three wetting and drying cycles, the concentration of colloids declined, whereas the small SMA without chemical pre-treatments reaggregated to particles with larger average diameters up to 10 µm, with the size depending on the clay content. Intriguingly, the gain in size was more pronounced after Fe removal, but it was not affected by OC removal. We suggest that Fe (hydr)oxides impact the stability of small SMA primarily via cementing the aggregates to smaller size. In contrast, the effect of OC was restricted to the size of colloids, gluing them together to small SMAs within defined size ranges when OC was present but releasing these colloids when OC was absent.
Modelling the impact of iceberg melt on glacier-ocean interaction, east Greenland
Authors: Davison Ben , Cowton Tom , Cottier Finlo , Sole Andrew
Published: March 2020

The melting of icebergs within Greenland’s iceberg-choked fjords provides a large and distributed source of liquid freshwater throughout the year. However, the impact of this freshwater flux on fjord properties and circulation remains unclear, in part because icebergs have typically been neglected in modelling studies that seek to examine interaction between glacier and fjord processes. Here, we modify a general circulation model to simulate the impact of iceberg submarine melting within Kangerdlugssuaq and Sermilik fjords in east Greenland, home to two of Greenland’s largest glaciers. We find that iceberg submarine melting results in cooling of up to 5°C and freshening of up to 0.6 psu throughout the upper 100-200 metres of both fjords, compared to experiments without icebergs. The resulting freshwater flux, which is of the order of hundreds of cumecs, is capable of driving a weak overturning circulation. This augments the runoff-driven circulation at depth but can oppose the up-fjord flow of warm near-surface waters, resulting in an increase in up-fjord heat flux at depth but a decrease near the surface. By increasing subsurface iceberg melt rates, ocean warming will therefore expedite iceberg deterioration within ice mélange and may further increase ocean thermal forcing of tidewater glacier grounding lines. Our results highlight the significant impact that icebergs have on fjord water properties and circulation in Greenland’s iceberg-choked fjords, demonstrating the importance of including these processes in studies that seek to examine interactions between the ice sheet and the ocean.
SEAWIFS4MERIS adaptation to OLCI
Authors: Dermann Diana , Kosmale Miriam , Popp Thomas
Published: March 2020

SeaWIFS4Meris is retrieving AOD at 550nm by fitting reflectance spectra at TOA to those measured by the MERIS instrument (ENVISAT). The OLCI instrument on Sentinel 3 is the successor of MERIS. The SeaWiFS4Meris Algorithm for AOD retrieval has been subsequently adapted to process OLCI data. Compared to AATSR/SLSTR OLCI and MERIS offer a better coverage due to a wider swath (1150km for OLCI and MERIS compared to 512km for AATSR).

We present aerosol retrieval results for the second half of 2019 together with their validation.

Based on the validation, next steps for improving the algorithm are defined. First, the albedo will be recalculated based on OLCI data - currently the albedo data calculated from MERIS data of 2008 is used. Secondly, possibilities for updating the cloud mask algorithm will be analyzed using the additional bands of OLCI. Lastly, the treatment of aerosol types will be inspected.
Authigenic pyrite formation in iron-dominated marine sediments of the Mozambique Margin
Authors: Zindorf Mark , Rooze Jurjen , Meile Christof , Jouet Gwenael , März Christian , Newton Robert , Rouxel Olivier , Pelleter Ewan , Brandily Christophe , Gayet Nicolas , Pastor Lucie
Published: March 2020

Sediment deposition along continental margins and especially close to the outlets of major river systems is highly dynamic and influenced by changing environmental conditions, such as sea-level variations and the shifting of ocean currents.
The upper slope of the Mozambique margin (SE Africa) receives its sediments from the Zambezi River and is the largest river-fed deposition center along the Eastern African Margin. Global sea level rise during the last glacial-Holocene transition led to a re-routing of the Zambezi River sediment plume. This caused order-of-magnitude changes in sedimentation rates along the shelf break of the Mozambique margin. The variable sediment input as well as changing organic matter load and quality resulted in non-steady state early diagenesis leading to changes in formation and upward flow of methane. This is reflected in temporally and spatially variable formation conditions of authigenic minerals (such as pyrite), especially at the sulfate-methane transition zone (SMTZ) where upward-diffusing methane is anaerobically oxidized by sulfate. Pyrite accumulations in sediment cores can be used to define the past positioning of SMTZs. The isotopic composition of sulfur in pyrite can provide information about the geochemical and environmental factors (e.g., availability of methane, sulfate, reactive iron) controlling the formation of these authigenic minerals during different times of sediment deposition.

We present geochemical data from sediment cores acquired in 2015 during the PAMELA-MOZ4 campaign onboard R/V Pourquoi Pas? offshore Mozambique. A reactive transport model is used to simulate the evolution of early diagenetic conditions over the time of sediment deposition (i.e., the last 27,000 years). By reproducing the currently observed mineral accumulations, the temporal development of methane generation and upward flux, and the past positioning of the SMTZ, can be reconstructed. With this, we are able to put a time constraint on past events of authigenic mineral accumulation and reveal their response to sedimentation rate changes caused by sea-level rise. We further discuss isotope signatures of small-scale diagenetic processes at the Mozambique margin.

This research was co-funded by TOTAL and IFREMER as part of the PAMELA scientific project.
Modelling the Precipitation Impacts on Wastewater Influent Volumes in Galway, Ireland
Authors: Saikia Sukanya , Clifford Eoghan , Ryan Paraic
Published: March 2020

Precipitation plays a critical role in determining the influent volumes of wastewater for many urban wastewater treatment plants (WWTPs). Urban stormwater runoff, resulting from impervious surfaces and infiltration, can significantly increase WWTP influent volumes above normal dry weather flows. Other factors such as demographics and changing landuse landcover can also impact influent volumes. In the context of climate change, projected changes in precipitation events could, in particular, cause significant challenges to existing collection networks. However, there has been limited research to date on the direct impacts of various precipitation variables on combined collection systems. This research aims to assess the impacts of precipitation on influent wastewater volumes using an urban area case-study in Ireland. In Ireland, most collection networks in urban areas are combined foul and storm water systems. Thus, these networks, and their connected wastewater treatment plants, can be impacted significantly by storm water (both in terms of volume and wastewater characteristics).  

Daily data of influent volume and precipitation for a relatively large municipal wastewater treatment plant in Ireland for the period of 2011-2018 was used for this study. The precipitation intensity was categorised based on the percentile values to obtain clarity on its effects on influent volume. This study investigated the relationship between influent wastewater volume and precipitation, number of wet days (wet day characterised by rainfall greater than or equal to 1 mm) and the number of zero rainfall days. It was observed that on a monthly basis, the relationship between average daily values of influent volume and precipitation showed significant linear trends with R2 values as high as 0.86 for all the years. Average daily influent volume estimated per month showed strong relationships and significant trends for all years when analysed with the number of wet days and separately with the number of zero rainfall days in that month. Impacts of rainfall events were generally seen on the same day with residuals over the following days, meaning any time lag could not be detected. The dry weather flow was estimated by averaging the flow of consecutive zero rainfall days excluding the flow values of the first two dry days of such an event to eliminate the effects of any preceding rainy days. This analysis gave insight to the impacts of other factors such as demographic changes due to tourism or seasons on influent wastewater volumes. Factors which were also considered in this study included the impacts of tides on the sewer network. This work is informing the ongoing analysis of a further 16 wastewater treatment plants which will enable improved planning and adaptation of wastewater infrastructure to climate change.
Spatial patterns in winter wheat development related to soil properties and historic management. A case study from central Belgium.
Authors: Goffart Dimitri , Dvorakova Klara , Curnel Yannick , Limbourg Quentin , Crucil Giacomo , Planchon Viviane , Van Oost Kristof , van Wesemael Bas
Published: March 2020

Intra-field heterogeneity of soil properties is function of complex interaction between biological, physical factors and historic agricultural management. Quantifying the spatial patterns of soil properties such as soil organic carbon (SOC), nitrogen (N), phosphorous, exchangeable cations, pH, soil texture will contribute to an optimization of fertilizer application and crop yields. We tested the capacity of the multispectral Micasense rededge camera mounted on a UAV in order to map the development of winter wheat and related the Red-Edge NDVI (RENDVI) from the sensor to the Plant Area Index (PAI) measured in the field. The geo-referenced grain yield of the winter wheat was measured by a combine harvester and the top soil characteristics analysed by a grid based sampling. The spatial patterns in RENDVI at three phenological stages were mapped together with the yields. For each of these images conditional inference trees were used to derive the soil properties that significantly influenced these spatial patterns. Within-field variation in PAI (cv 41 % in March, 27% in April and 9 % in May) and yield (cv 4%) can be observed. The spatial patterns of RENDVI are rather constant and their correlation with yields is highest in March and April (r=0.64). Soil properties explain between 67 to 79 % of the variance in vegetation index throughout the growing season as well as 67 % of the variance in yield.  Legacy effects of land consolidation two years earlier reflected in the field lay-out, pH and exchangeable K are significant factors explaining around 12-18 % of the variance in crop yield each. The SOC contents were overall low (8-15 g kg-1). Hence, the N supply resulting from SOC mineralization throughout the growing season covered less than 10% of the crop needs and the yield patterns did not reflect the variation in SOC contents.
Heat stress indicators in CMIP6: Estimating future trends and exceedances of critical physiological thresholds
Authors: Schwingshackl Clemens , Sillmann Jana , Sandstad Marit , Aunan Kristin
Published: March 2020

Global warming is leading to increased heat stress in many regions around the world. An extensive number of heat stress indicators has been developed to measure the associated impacts on human health. Here we calculate eight heat stress indicators for global climate models participating in the Coupled Model Intercomparison Project phase 6 (CMIP6) and compare their future trends and exceedances of critical physiological thresholds with particular focus on highly populated regions. The heat stress indicators are selected to represent a range of different applications, such as extreme heat events, heat-related losses in worker productivity, heat warnings, and heat-related morbidity and mortality. Projections of the analyzed heat stress indicators reveal that they increase significantly in all considered regions as function of global mean temperature. Moreover, heat stress indicators reveal a substantial spread ranging from trends close to the rate of global mean temperature up to an amplification of more than a factor of two. Consistently, exceedances of critical physiological thresholds are strongly increasing globally, including in several densely populated regions, but also show substantial spread across the selected heat stress indicators. Additionally, the indicators with the highest exceedance vary for different threshold levels, suggesting that the large indicator spread is associated both to differences in trend magnitude and threshold levels. The usage of heat stress indicators that are suitable for each specific application is thus crucial for reliably assessing impacts of future heat stress, while inappropriate indicators might lead to substantial biases.
Inverting fluvial network topology to understand landscape dynamics
Authors: Grieve Stuart , Mudd Simon , Clubb Fiona , Singer Michael , Michaelides Katerina , Chen Shiuan-An
Published: March 2020

The topology of fluvial networks has long been studied, with Horton's laws describing relationships between stream order, stream density, and stream length often cited as fundamental governing principles of drainage basin development. Building upon these principles, small scale studies have identified patterns of self-similarity in drainage networks in the continental USA, suggesting that to some extent, river networks self-organise in a scale invariant manner. More stringent measures of self-similarity have also been developed, which quantify the fractal nature of side branching structures in fluvial networks. Using such metrics, studies have identified similarities between leaf vein structures and fluvial networks, and have identified a potential climatic signature in North American river topology.

The appeal of such techniques over traditional methods of channel analysis using topographic data is that in self-similar networks, the precise location of channel heads is unimportant, allowing analysis to be performed at unprecedented scales, and in locations where data quality is limited. Here, we attempt to reconcile these two suites of techniques to understand the potential and limitations of network topology as an indicator of broader landscape dynamics. We achieve this through the analysis of fluvial networks extracted at a global scale from the Shuttle Radar Topography Mission dataset alongside other global earth observation data.
Observed Evidence of a Stable Atlantic Meridional Overturning Circulation since the 1990s
Authors: Fu Yao , Li Feili , Karstensen Johannes , Holliday N. Penny , Wang Chunzai
Published: March 2020

The Atlantic Meridional Overturning Circulation (AMOC) is crucially important in the global climate system due to its role in the meridional heat and freshwater distribution. Model simulations and constructed AMOC indices suggest that the AMOC may have been weakening for decades. However, direct AMOC observations, introduced in 2004 in the subtropics (the RAPID program) and in 2014 in the subpolar North Atlantic (the OSNAP program), are not sufficiently long to capture changes dating back to previous periods. Here we use repeated hydrographic sections in the subtropical and subpolar North Atlantic through the early 1990s to the mid-2010s, combined with a box inverse model that is constrained using satellite altimetry, to analyze hydrographic changes and the AMOC. In combination with a state-of-the-art ocean state estimate, GECCO2, we show that despite dramatic hydrographic changes in the subtropical and subpolar North Atlantic over the past two and half decades, the AMOC has not significantly weakened over the same period. Our hydrography-based estimates also illustrate a remarkably stable partition of the subpolar overturning between the Labrador basin and the eastern subpolar basins on decadal timescales since the 1990s.
Mapping and Classification of upland soils formed from sand stone and micaceous schist in Koko/Besse Area in North western Nigeria.
Authors: Ande Olufunmilayo , Are Kayode , Adeyolanu Olateju , Oke Adebayo , Ojo Oluremi , Denton Olubunmi , Oluwatosin Gabriel , Taiwo Omodele , Lucas Adelabu , Adediran James
Published: March 2020

The study was set up to characterize upland soils of Koko/Besse Local Government Area  in North western Nigeria for sustainable intensification of cropped land. Soil units were identified using flexible grid method. Based on the geology, morphology and  physical  properties the soil units were identified provisional  Soil map was produced in a GIS environment using combination of DEM and field boundary parameters. The major pedogenic processes included ferruginisation, lessivage,  and mineralization. All these processes combined to form ferrallitic soils with  low organic matter content. The soil units on sand stone were generally low in  Cation Exchange Capacity (CEC) (0.88-3.82cmol/kg) while the soils formed from metamorphic rock had low to high CEC (2.92-12.44) The Phosphorus distribution was generally low (0.71–6.96 mg/kg) while Nitrogen content was less than or equal to 0.07%in all the units Soil organic carbon ranged from 0.21-0.95%.  The major pedogenetic processes included, cummilization and  gleization at the lower slopes while ferrolyses and lessivage and ferruginisation with formation of iron stone rubbles and plinthite was dominant at upper slope position of the soils formed from sand stone. While mineralization, salinisation and lessivage were dominant processes with basement complex. The soil units were classified using USDA classification system. The soils on sand stone include  Plinthustults, Kandiustults, Dystrochrept. Natrustalf and Kandiustalf dominated areas underlain by micaceous ferromagnessiun rock. Based on the characterization, sustainable land use will involve use of fortified organic fertilizers, green manure, leguminous cover crops and erosion control measures such as vetiver grass strips
Avalanche hazard in low-mountain part of Eastern Carpathians
Authors: Ridush Oles , Ridush Bogdan , Kholiavchuk Daria
Published: March 2020

The goal of our research is to forecast the possible avalanches in the zones of active deforestation, especially situated close to the infrastructure objects and settlements.
Despite the fact, that in Ukrainian Carpathians snow avalanches were observed by the Ukrainian Hydrometeorological Service, some recent events showed us, that it does not fulfill the current situation. The observations are regularly held in alpine and subalpine zones (>1300m. a.s.l.) of mountain ranges, in the same time territories with lower altitudes were not studied.
Due to the active deforestation of the region in recent years, it appeared in new territories with conditions suitable for the appearance of avalanches. Because deforestation is mainly held on territories with lower altitudes, which are often densely settled, it makes such avalanches hazardous for the infrastructure and settlements. One of such avalanches occurred on the slope near village Kruhlyi (Rakhiv District, Zakarpatska oblast') in February 2019, that caused blocking of the international highway with 300 m3 of ice and snow. The avalanche occurred on the deforested area with altitudes between 400 and 480 m a.s.l., inclination around 28â° and 150m long. This event changes our vision in avalanche expectancy in the Carpathian Mountains to much lower altitudes. Research is currently being held based on data about deforestation and detecting areas with suitable avalanche properties.
This research was supported by the project “Snow-avalanche activity from Romanian and Ukrainian Eastern Carpathians”, funded by AUF and IFA Romania.
Semi-quantitative understanding of source contribution to nitrous acid (HONO) based on 1 year of continuous observation at the SORPES station in eastern China
Authors: Liu Yuliang
Published: March 2020

Nitrous acid (HONO), an important precursor of the hydroxyl radical (OH), has long been recognized as of significance to atmospheric chemistry, but its sources are still debated. In this study, we conducted continuous measurement of HONO from November 2017 to November 2018 at the SORPES station in Nanjing of eastern China. The yearly average mixing ratio of observed HONO was 0.69±0.58 ppb, showing a larger contribution to OH relative to ozone with a mean OH production rate of 1.16 ppb h−1. To estimate the effect of combustion emissions of HONO, the emitted ratios of HONO to NOx were derived from 55 fresh plumes (NO∕NOx > 0.85), with a mean value of 0.79 %. During the nighttime, the chemistry of HONO was found to depend on RH, and the heterogeneous reaction of NO2 on an aerosol surface was presumably responsible for HONO production. The average nighttime NO2-to-HONO conversion frequency (CHONO) was determined to be 0.0055±0.0032 h−1 from 137 HONO formation cases. The missing source of HONO around noontime seemed to be photo-induced, with an average Punknown of 1.04 ppb h−1, based on a semi-quantitative HONO budget analysis. An over-determined system of equations was applied to obtain the monthly variations in nocturnal HONO sources. Besides the burning-emitted HONO (accounting for about 23 % of the total concentration), the contribution of HONO formed heterogeneously on ground surfaces to measured HONO was an approximately constant proportion of 36 % throughout the year. The soil emission revealed clear seasonal variation and contributed up to 40 % of observed HONO in July and August. A higher propensity for generating HONO on aerosol surfaces occurred in severe hazes (accounting for 40 % of the total concentration in January). Our results highlight ever-changing contributions of HONO sources and encourage more long-term observations to evaluate the contributions from varied sources.
Land aerosol retrieval from MERSI onboard Chinese Fengyun-3
Authors: Yang Leiku , Hu Xiuqing , Wang Han , Liu Pei , He Xingwei , Du Weibing , Deng Anjian
Published: March 2020

The MEdium Resolution Spectral Imager (MERSI) onboard Chinese Fengyun-3 (FY-3) satellite is designed similar to MODIS and VIIRS, which would be an important supplement for multi-sensor measuring aerosol temporal and spatial distribution. But, there is no reliable aerosol product from MERSI by now. The plan of FY-3 missions is a sequence of eight satellites. Four have been launched, FY-3A in 2008, FY-3B in 2010, FY-3C in 2013, and recent FY-3D in the end of 2017. As the sensor MERSI becomes more mature, the demand of quantitative product is very urgent. Here, we apply MODIS land dark target (DT) algorithm to MERSI to test the quantitative ability of aerosol retrieval. Considering the sensor difference between MODIS and MERSI, we modified the process of gas absorption, cloud/snow/inland-water mask, pixel aggregation, and the most important part of band ratio for surface reflectance estimation. The global MERSI/FY-3C data of a whole year has been tested for retrieval. And the AEROENT data are used for ground validation. The scattering plot shows that MERSI AOD (aerosol optical depth) agrees well with AERONET observation that 70.7% collocations fall within expected error EE=±(0.05+0.15τ), which is even better than MODIS/TERRA AOD that 66.6% fall within EE. The global maps of monthly mean AOD are also consistent as well as MODIS. Finally, we made test to MERSI-II/FY-3D of 2 years data, the preliminary results also have a good validation and agree well with MODIS. The results of this talk indicates that the MERSI sensor has the quantitative ability for aerosol retrieval, and would be an important member of multi-sensor for aerosol measurements.
Future projections in tropical cyclone activity over multiple CORDEX domains from RegCM4 CORDEX-CORE simulations
Authors: Torres Abraham , Glazer Russell , Coppola Erika , Gao Xuejie , Hodges Kevin , Das Sushant , Ashfaq Moetasim
Published: March 2020

Under the Coordinated Regional Downscaling Experiment (CORDEX) initiative, simulations of tropical cyclones were performed using the latest version of the International Centre for Theoretical Physics (ICTP) Regional Climate Model 4 (RegCM4) at a spatial resolution of 25 km over four domains (Australasia, Central America, Western Pacific and South Asia). These simulations cover the 130-year period, 1970-2099, for two Representative Concentration Pathways, 2.6 (RCP2.6) and 8.5 (RCP8.5) emission scenarios and were driven by three General Circulation Models (GCMs) from phase 5 of the Coupled Model Inter-comparison Project (CMIP5). In these simulations, the potential changes in TC activity for future climate conditions over five areas of tropical cyclone formation (North Indian Ocean, the Northwest Pacific, North Atlantic, Australasia and Eastern Pacific) are investigated, using an objective algorithm to identify and track them. The RegCM4 simulations driven by GCMs are evaluated for the period of 1995–2014 by comparing them with the observed tropical cyclone data from the International Best Track Archive for Climate Stewardship (IBTrACS); then the changes in two future periods (2041-2016 and 2080–2099), relative to the baseline period (1995–2014), are analyzed for RegCM4 simulations driven by GCMs. Preliminary results show that RegCM4 simulations driven by GCMs are capable of most of the features of the observed tropical cyclone climatology, and the future projections show an increase in the number of tropical cyclones over the North Indian Ocean, the Northwest Pacific and Eastern Pacific regions. These changes are consistent with an increase in mid-tropospheric relative humidity. On the other hand, the North Atlantic and Australasia regions show a decrease in tropical cyclone frequency, mostly associated with an increase in wind shear. We also find a consistent increase in the future storm rainfall rate and the frequency of the most intense tropical cyclones over almost all the domains. Our study shows robust and statistically significant responses, often, but not always, in line with previous studies. This implies that a robust assessment of tropical cyclone changes requires analyses of ensembles of simulations with high-resolution models capable of representing the response of different characteristics of different key atmospheric factors.
Insurance Fund as an Adaptation Measure for Increasing Water Security in Basins Under Change
Authors: Gesualdo Gabriela , Souza Felipe , Mendiondo Eduardo
Published: March 2020

Extreme weather events are increasingly evident and widespread around the world due to climate change. These events are driven by rising temperatures and changes in precipitation patterns, which lead to changes in flood frequency, drought and water availability. To reduce the future impacts of natural disasters, it is crucial to understand the spatiotemporal variability of social, economic and environmental vulnerabilities related to natural disasters. Particularly, developing countries are more vulnerable to climate risks due to their greater economic dependence on climate-sensitive primary activities, infrastructure, finance and other factors that undermine successful adaptation. In this concept, adaptation plays the role of anticipating the adverse effects of climate change and taking appropriate measures to prevent or minimize the damage they may cause. Thus, the insurance fund is a valuable adaptation tool for unexpected losses reimbursement, long-term impacts prevention and encouraging risk mitigation. Although this approach is successful throughout the world and major organizations support insurance as an adaptation measure, the Brazilian insurance fund only provides support for rural landowners. Thus, we will evaluate the implementation of an indexed multi-risk insurance fund integrated with water security parameters, as an instrument for adaptation to climate change. We will use the SWAT+, a hydrosedimentological model, to assess the current conditions and future scenarios (up to 2100) of water security indices considering two International Panel on Climate Change (IPCC) Representative Concentration Pathways (RCP 4.5 and RCP 8.5). Then, we will incorporate those parameters to the Hydrological Risk Transfer Model (MTRH). Our results will provide optimized premium in current and future scenarios for supporting adaptation plans to climate change. Furthermore, to contribute to technical-scientific information addressing possible effects of climate change on the hydrometeorological variables and their spatiotemporal variability.
Is the banding in iron formations controlled by water transparency?
Authors: Herwartz Daniel
Published: March 2020

Banded Iron Formations (BIF’s) show a typical layering of Fe minerals and quartz that is observed at various scales ranging from micrometers to meters. Millimeter sized micro bands are commonly interpreted as annual layers so larger bands require decades or millennia to form, whereas micrometer sized nano bands have been interpreted to represents sub annual and even diurnal cycles. Because the mineralogical composition of BIF’s is not primary and because single-phase Fe(III) silica gel forms when Fe(III) (oxyhydr-)oxide precipitates in Si rich water, secondary processes are often invoked to explain the banding. However, trace element and isotope data point towards distinct sources for the Fe and Si rich bands, which is difficult to reconcile with a single phase starting material. In addition, the correlation of banding over long distances is inconsistent with most secondary models. Both primary and secondary models struggle to explain the versatile nature of the banding. I will present a conceptual model that could explain BIF layering at all scales and the more widespread formation of granular iron formations (GIF’s) in the Paleoproterozoic.

The concept builds on primary precipitation models postulating that banding forms due to some form of periodicity such as cyclic Fe or nutrient supply to the shelf. Fe(III) is mainly produced by phototrophic iron oxidizing bacteria. These photoferrotrophs are adapted to very low light levels corresponding to about 1% of the light level required by oxygen producing phototrophs allowing them to thrive deep down in the water column. The depth of Fe(III) production is mainly controlled by water turbidity which controls how deep photosynthetically available radiation (PAR) penetrates into the water column. Eutrophic conditions result in turbidity induced by the biomass itself resulting in shallow Fe(III) production depth and the formation of Fe rich bands. During oligotrophic stages, Fe(III) is only produced deep down in the water column, so that silica rich bands can form. In this case, Fe(III)-silica co-precipitation is not an issue because silica precipitates in the Fe(III) free upper water column. Reactive transport modelling shows that besides upwelling and nutrient supply, alternating Fe(III) production depth are mainly associated with changing light conditions. Hence the model predicts annual layering, but also local occurrences of diurnal cycles. Larger periodicities could be associated with: 1) nutrient supply patterns; 2) formation and clearing of atmospheric haze; or 3) additional sources of turbidity in the water column such as silicate particles, MnO2 particles or metal sulfides. These additional sources of turbidity become more important in the Paleoproterozoic and could be responsible for the more widespread occurrences of GIF’s, indicative of Fe(III) production above storm wave base. The additional factor light, is quite versatile in producing periodicities at variable scales.