bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of future municipal solid waste production. Case study in Valencia region (Spain)
Authors: Carnero-Pousa María-Luisa , Rodrigo-Ilarri Javier , Rodrigo-Clavero María-Elena
Published: March 2020

Municipal Solid Waste (MSW) management activities are an important tasks of both national and municipal governments as they can induce significant impacts on the environment, the economy and the living quality of the population involved.

The optimal design of a MSW management plan depends greatly on the waste production values and its distribution over the territory. This production depends mainly on the socioeconomic level of its inhabitants. On the scientific literature several studies have already been carried out, concluding that there exist a direct relationship between the waste production of a certain country or region and its Gross Domestic Product (GDP). Therefore, if GDP increases, so will the rate of waste production, although not necessarily at the same rate.

The objective of the work was to carry out an evaluation of the future production of (MSW) within the V5 production area inside Valencia Region (Spain) in the 2012-2034 time horizon. The year 2011 was used as the starting point for the simulation as this was the last year in which the population census was taken. The correlation between the evolution of the economic growth indicators and the waste production indicators was analyzed. Results showed a linear correlation between all the variables studied so that variations in one of them are reflected in the same direction in the others.
Accelerated increases in global and Asian summer monsoon precipitation from future aerosol reductions
Authors: Wilcox Laura , Liu Zhen , Samset Bjørn , Hawkins Ed , Lund Marianne , Nordling Kalle , Undorf Sabine , Bollasina Massimo , Ekman Annica , Kirshnan Srinath , Merikanto Joonas , Turner Andrew
Published: March 2020

There is large uncertainty in future aerosol emissions scenarios explored in the Shared Socioeconomic Pathways (SSPs), with plausible pathways spanning a range of possibilities from large global reductions in emissions to 2050 to moderate global increases over the same period. Diversity in emissions across the pathways is particularly large over Asia. CMIP6 models indicate that rapid anthropogenic aerosol and precursor emission reductions between the present day and the 2050s lead to enhanced increases in global and Asian summer monsoon precipitation relative to scenarios with weak air quality policies. However, the effects of aerosol reductions don’t persist in precipitation to the end of the 21st century, when response to greenhouse gases dominates differences across the SSPs. The relative magnitude and spatial distribution of aerosol changes is particularly important for South Asian summer monsoon precipitation changes. Precipitation increases here are initially suppressed in SSPs 2-4.5 and 5-8.5 relative to SSP 1-1.9 and 3-7.0 when the impact of East Asian emission decreases is counteracted by that due to continued increases in South Asian emissions.
Spatial early warnings of the transition to superrotation: Studying a bifurcation in the general circulation using an idealized GCM
Authors: williamson mark
Published: March 2020

A superrotating atmosphere, one in which the angular momentum of the atmosphere exceeds the solid body rotation of the planet, occurs on Venus and Titan. However, it may have occurred on the Earth in the hot house climates of the Early Cenozoic and some climate models have transitioned abruptly to a superrotating state under the more extreme global warming scenarios. Applied to the Earth, the transition to superrotation causes the prevailing easterlies at the equator to become westerlies and accompanying large changes in global circulation patterns. Although current thinking is that this scenario is unlikely, it shares features of other global tipping points in that it is a low probability, high risk event.

More than anything though, this tipping point serves as an ideal example to test some spatial early warning methods. I’ll show some preliminary results how the critical spatial modes and time scales change through the transition to superrotation using an idealized general circulation model (GCM), Isca.
Cascading effects of the 2018-2019 German drought: empirical evidence from media reports
Authors: Madruga de Brito Mariana , Kuhlicke Christian
Published: March 2020

During 2018-2019 Germany experienced a severe drought which affected 90% of its territory, especially the North and the East. Its consequences have been far-reaching for agriculture, forestry and aquatic ecosystems. Low water levels, including at the Rhine, impaired waterborne transportation, which led to increased energy prices. Furthermore, nuclear power stations lowered their production or shut down and hydropower and industrial outcomes were reduced. Despite these consequences, the inter-sectoral effects of the 2018-2019 German drought are still largely unexplored due to the inherent complexity in their assessment.

This study seeks to close this gap by providing a methodology for characterizing drought impacts and its interdependencies at the district level. The proposed approach allows understanding the compounding and cascading consequences of long-term droughts as a socio-economic and ecosystem disturbance. To this end, we conducted a comprehensive analysis of the 2018-2019 drought impacts across Germany based on a quantitative content analysis of 5.074 newspaper articles published between April 2018 and August 2019. A total of 4.878 unique impacts within 25 sub-categories were identified. These were then analyzed over time and space, aiming to identify emerging trends. Additionally, network analysis was employed to better understand the dynamics and interrelationships between the cross-sectoral impacts. Validation was conducted by carrying out a correlation analysis between the obtained results and the monthly soil moisture index, crop losses statistics and the population drought awareness.

The developed coding system was in 95.4% of the cases accurate, meaning that the proposed approach can provide reliable information for classifying a large amount of data. Results highlight the complex nature of assessing drought impacts, describing the propagation of drought and related direct and indirect impacts across various sectors. Overall, agriculture was severely affected in most of the districts in 2018 whereas impacts on forestry were predominant in 2019. As expected, the reduction of crop productivity was closely interlinked with impacts such as early harvesting of crops, shortage of feed, reduction of livestock, economic losses and need for government assistance. The frequency of the impacts varied regionally, with losses to industry concentrated in Nordrhein-Westfalen and impacts to livestock farming concentrated in Sachsen-Anhalt. To the best of our knowledge, the collected and analyzed impact report data constitutes the first attempt to quantify the cascading effects of drought impacts across NUTS 3 regions. The proposed methodology can be applied to other study areas and results can support policy-planning and inform drought impacts forecasting.
Manufactured Soil Aggregates for Studying Microhabitats
Authors: Harvey Harry , Wildman Ricky , Mooney Sacha , Avery Simon
Published: March 2020

Environmental perturbation, anthropogenic or otherwise, can have a profound effect on soil microbiota and essential biogeochemical processes. The general resistance and adaptation of yeasts and other fungi to stressors has been well studied in vitro however, the influence of key physical variables, such as how soil structure regulates fungal response to perturbation, is poorly understood. In this study, we developed an approach to manufacture soil macroaggregates that are characteristically similar to their natural counterpart (determined by X-ray CT) and with defined microbial composition. This new tool allowed us to examine the influence of soil aggregation on fungal stress response by manufacturing aggregates with yeast cells either within, or on, the aggregate surface. Environmental stressors including heavy metals, anoxia, and heat stress were applied to these aggregates to capture an array of environmental stressors and assay differences in survival between exo-and-endo aggregate cells. Results generated with this new tool indicate that the location of yeast cells in soil macroaggregates can impact on their survival, in a stressor- and time-dependent manner.
UAV photogrammetry and 3D scan data for topographic mapping and monitoring of maritime heritage
Authors: Barry James , Craven Kieran , O'Toole Ronan , Cullen Sean
Published: March 2020

Cultural heritage in maritime areas experience changes via natural and anthropogenic processes. This change must be monitored on a range of temporal and spatial scales to understand the evolution of these environments, particularly in the context of projected climate change yielding increased sea-levels and storm frequency. Commercial survey grade unmanned aerial vehicle (UAV) and 3D scan equipment, data processing and analysis tools are available to coastal and heritage managers, engineers and researchers.

This study, undertaken as part of the CHERISH project, analyses the use of photogrammetry via UAVs and 3D scan data from scanning total stations in Irish coastal locations with tangible cultural heritage to produce orthoimage mosaics and digital surface models. These products extend and complement acoustic bathymetric data in mapping vulnerable coastal regions. Results indicate that combining relevant techniques to produce seamless onshore-offshore maps can provide high-resolution information about emergent and submergent coastal geomorphology on a range of scales for use in monitoring and managing coastal heritage sites.
Combining (U-Th-Sm)/He dating and geochemical budget to understand laterite formation
Authors: Ansart Claire , Calmels Damien , Gautheron Cécile , Monvoisin Gaël , Agrinier Pierre , Couëffe Renaud , Roig Jean-Yves , Quantin Cécile
Published: March 2020

Laterite formations are deep regoliths, up to one hundred of meters thick, that represent about 80% of the global soil volume. Formed under tropical conditions, laterites result from successive chemical weathering reactions over long periods up to tens of millions of years. Laterites can thus be seen as both an actor of the long-term carbon cycle, through CO2 consumption by silicate weathering and witness of the long-term climate evolution. Indeed, secondary minerals found nowadays in lateritic profiles may have recorded past environmental conditions that prevailed at the time of their formation. Despite the large distribution of lateritic formations around the world, their timing and processes of formations as well as their preservation over long period of time remain unclear.

Here, we investigate an entire weathering profile developed on the Guiana Shield, in Brownsberg mountains, Suriname. The sampling region has remained in equatorial position for the last 100 Myr and has seen lateritic development since early Tertiary [1]. Such latitudinal stability offers the possibility to look at links between long-term climate evolution or climatic events and long-term chemical weathering processes.

The lateritic profile shows a strong loss in both alkali and alkaline-earth elements as well as a desilication, and an enrichment in Fe, particularly in the duricrust. The study of trace elements and rare earth elements highlights various geochemical processes behind the development of a lateritic – bauxitic profile.

 (U-Th-Sm)/He ages of iron oxides from the duricrust show the presence of multiple generations of Fe oxides, demonstrating that the Brownsberg profile underwent multiple dissolution and recrystallization phases since its formation, at least 19.9 ± 1.8 Ma ago. These successive weathering processes may have led to the particular enrichment in the profile such as the one observed for Fe and V in the duricrust. Measurement of d18O – dD on secondary minerals, i.e. kaolinite and Fe-oxides s.l., will help to connect mineralogical and geochemical variations with the environmental conditions that prevailed at the time of their formation [2].

[1] Theveniaut and Freyssinet, 2002. Pal. Pal. Pal., 178, 91-117

[2] Girard et al., 2000. GCA, 64 n°3, 409 – 426
The influence of bottom water intrusion events on the biogeochemistry of a coastal fjord
Authors: Rakshit Subhadeep , Cogswell Andrew , Haas Sebastian , Devred Emmanuel , Davis Richard , Patterson Kate , Wallace Douglas , Algar Christopher
Published: March 2020

Lack of bottom water exchange in fjord-like estuaries can result in low oxygen conditions and creating sites of redox-sensitive biogeochemical processes, such as denitrification. In many of these systems, occasional intrusions of well-oxygenated bottom water may temporarily alter redox gradients and sediment-water biogeochemistry. Quantifying the magnitude and importance of these changes is a challenge due to the short timescales over which these events can occur. Here we present results from Bedford Basin, a 71 m deep coastal fjord in eastern Canada, where a 20-year, weekly timeseries of bottom water conditions indicates that autumn wind-driven intrusion events are a common, but infrequent, feature of its circulation. To examine the impact of these intrusions on biogeochemistry, we deployed a benthic instrument pod at 60 m depth to record high-resolution measurements of temperature, salinity, nitrate, oxygen, and fluorescence over a 4-month period during the fall of 2018.  During this time we captured two intrusion events, one in mid-Oct and another in mid-Nov. Both intrusion events occurred on a timescale of hours and resulted in sharp changes in temperature, salinity, oxygen, and nitrate.  We used these measurements to constrain a coupled sediment-water column reactive transport model to examine the immediate and annual impacts of these intrusion events on oxygen and nitrogen dynamics in the basin bottom waters and across the sediment-water interface.
A study on implementing catchment-scale rootzone water storage capacities, derived from climatic parameters, in the HTESSEL land surface scheme
Authors: van Oorschot Fransje , Alessandri Andrea , van der Ent Ruud , Hrachowitz Markus
Published: March 2020

Evaporation is a key flux in both Earth’s water and energy balances. It is largely controlled by the transport of water from the subsurface to the atmosphere, through the roots of vegetation. The water storage capacity in the rootzone is a key parameter in predicting evaporation fluxes in land surface models. Drought predictions are of particular interest because the size of the rootzone-storage-reservoir determines how long into the dry season vegetation is able to evaporate. Whereas climate is the major driver of root development, the storage in the rootzone in the HTESSEL land surface scheme is only dependent on soil type and model soil depth. Moreover, the model describes root parameters by tables based on observations of individual plants that do not represent ecosystem scales. This research analyses the effect of implementing rootzone water storage capacities estimated with catchment-scale mass balances, in the land surface model HTESSEL on water and energy fluxes for 15 Australian river catchments.

This study found that the storage capacity in the vegetation’s rootzone represented in HTESSEL is larger than the mass-balance derived estimates. This leads to an underestimation of river discharge and overestimation of evaporation fluxes by the model, with significantly larger errors in the dry season. Implementation of the climate-based rootzone storage estimates in the current HTESSEL scheme leads to small model improvements regarding long term mean discharge predictions, but larger improvements in dry season discharge predictions. Transpiration fluxes in the dry season are directly linked to the size of rootzone water storage reservoir. The results indicate that inadequate rootzone representation could result in errors in modelled discharge and evaporation fluxes in the land surface model HTESSEL.

This study shows that investigating uncertainties in the representation of the rootzone in the HTESSEL land surface model is paramount. Future research is required to improve the representation of the rootzone in climate models.
The Westernmost Mediterranean evolution: A review of the Alboran and Algero-Balearic basins stratigraphy
Authors: Gómez de la Peña Laura , Ranero César , Gràcia Eulàlia , Booth-Rea Guillermo
Published: March 2020

The Alboran Basin is the westernmost of the Mediterranean basins. It is composed of different sub-basins and connects toward the east with the Algero-Balearic Basin. Regional studies of these basins are mainly from the ´90s, but the restricted seismic coverage and generally low quality (old acquisition and processing methods) of the seismic profiles were not enough to perform a detailed analysis of the entire sediment infill. More recent works characterize in detail a particular area, but the correlation between the different sub-basins remained beyond the scope of those works. Furthermore, these recent works are usually focused only on the Messinian and younger stratigraphy. Thus, the correlation of the sediment history across the entire region and its integration with the regional tectonic evolution has not been achieved. This results in a bunch of models, different for each sub-basin and not always coherent among them, which makes difficult the understanding of the geodynamic evolution of the region

Based on ~4500 km of new and reprocessed multichannel seismic profiles, together with well and dredge data, we are able to review the westernmost Mediterranean stratigraphy at a regional scale. We have correlated the sediment units deposited since the beginning of the formation of the different sub-basins, and we present for the first time a coherent stratigraphy and large-scale tectonic evolution of the whole region. The results provide the information to test and refine models of the geodynamic evolution of the westernmost Mediterranean.

The main objectives are: (i) To define a seismostratigraphy framework for the entire region, integrating previous interpretations and correlating the sedimentary units among depocentres; (ii) To propose an evolutionary model for each sub-basin; and (iii) To integrate all sub-basins results in an updated general kinematic model for the westernmost Mediterranean region.

Main results shed light on the particular evolution of each sub-basin as well as in the entire basin evolution. The Late Oligocene - Miocene represents the formation stage of the basins, controlled by the evolution of the Gibraltar subduction system. During this period, each sub-basin shows different sedimentary units, supporting differences in their evolution. The Plio-Quaternary corresponds to the deformation stage, driven by the Eurasian-African plates convergence. The Plio-Quaternary sediments are covering the entire area, instead of being restricted to the sub-basins. This latter period is characterized by contractional and strike-slip deformation, accommodated mainly by re-activation of pre-existing crustal structures.
Effects of depth and land use on vertical soil properties and their contributions to ecosystem services in Yanhe watershed
Authors: Yang Siqi , Zhao Wenwu , Pereira Paulo
Published: March 2020

Abstract: The increasing atmospheric carbon dioxide (CO2) and nitrogen (N) deposition along with human activities had important effects on soil properties and influenced ecosystem service (ES) delivery. Since GFGP (Grain for Green Project) implementation in China, dominant ES in Loess Plateau such as soil conservation and carbon storage increased substantially. However, there are few researches on ecological mechanism to explain provision of multiple ES, which may result in weak theoretical foundation to support policy and management. Here, we assess the impact of different land uses (forest, shrubland, grassland, cropland and orchard) on soil properties (texture, moisture, SOC, TN, TK, TP, C:N ratio) at different depths (0-100 cm) in Yanhe watershed (China). The results showed that soil texture sand and silt content were significantly higher in shrubland than in orchard and cropland, while clay content was significantly higher in forest. No differences were observed in soil moisture. Similar results were identified in TP and TK. SOC was significantly higher in forest soils compared to other land uses while TN had the lowest values among land uses, which cause carbon storage ES increased after transforming cropland to forest and grassland. Though there were significant differences in SOC and TN, the C:N ratio was significantly consistent in different depths and land use types. In addition, Redundancy analysis revealed that altitude and precipitation were the factors that influenced more soil properties.

 

 

 
Data collections of ESA DUE GlobPermafrost and ESA CCI+ Permafrost
Authors: Bartsch Annett ,   ESA DUE GlobPermafrost and ESA CCI+ Permafrost Teams
Published: March 2020

A Permafrost Information System (PerSys) based on satellite data has been setup as part of the ESA DUE GlobPermafrost project (2016-2019, www.globpermafrost.info). This includes a data catalogue as well as a WebGIS, both linked to the Pangaea repository for easy data access.

The thematic products available include InSAR-based land surface deformation maps, rock glacier velocity fields, spatially distributed permafrost model outputs, land surface properties and changes, and ground-fast lake ice. Extended permafrost modelling (time series) is implemented in the new ESA CCI+ Permafrost project (2018-2021, http://cci.esa.int/Permafrost), which will provide the key for our understanding of the changes of surface features over time. Special emphasis in CCI+ Permafrost is on the evaluation and development of land surface models to gain better understanding of the impact of climate change on permafrost and land-atmosphere exchange. Additional focus will be on documentation of kinematics from rock glaciers in several mountain regions across the world supporting the International Permafrost Association (IPA) action group ‘rock glacier kinematics as an essential climate variable’.

We will present the Permafrost Information System including the time series (2003-2017) of the first version of ground temperatures and active layer thickness for the entire Arctic from the ESA CCI+ Permafrost project. Further on, details on the user requirements collection process will be provided. Ground temperature is calculated for 0, 1m, 2m, 5m, and 10 m depth and has been assessed based on a range of borehole data. A survey regarding data repositories containing for validation relevant borehole data has been conducted. The records have been evaluated for the project purpose and harmonized. The resulting database will be eventually also made publicly available.
Climatic change caused larger variation of spring phenology in temperate semi-dry grasslands in China
Authors: Zhou Xuancheng , Fu Yongshuo , Zhang Yaru
Published: March 2020

Vegetation phenology is highly sensitive to climate change. Previous studies focusing on the trends of phenological events have found that temperature and precipitation primarily regulate the dates of spring phenology in temperate grasslands. However, the variation of spring phenology and its controlling factors are still unclear. In this study, we investigated the start of the growing season (SOS) in temperate semi-dry grasslands in China using five methods, and determined the variation of SOS and its primary factor over the study period 1982-2015. We found that, in line with previous studies, the SOS date did not change significantly during the entire study period 1982-2015, but its variation increased significantly from the first subperiod (1982-1998, Std: 8.8±1.1 day) to the second (1999-2015, Std: 10.3±1.1 days), the latter of which coincides with fast warming. The larger variation in SOS may be caused by the different climatic drivers on phenology in different areas. The fluctuation of temperature was significantly increased over the study area and subsequently may result in a larger variation of SOS. Furthermore, precipitation and soil moisture has increased until the mid-1990s, which may lead to the removal of water as a limiting factor and increase the response of semi-dry grassland spring phenology to temperature, and finally result in larger variation in SOS.
Detecting small scale spatial heterogeneity and short-term temporal variability of CO2 flux dynamics in agricultural used landscapes using a robotic chamber system
Authors: Vaidya Shrijana , Augustin Juergen , Sommer Michael , Schmidt Marten , Rakowski Peter , Hoffmann Mathias
Published: March 2020

­­­Improved agricultural practices sequestering additional atmospheric C within the soil are considered as one of the potential solution for mitigating global climate change. However, agricultural used landscapes are complex and their capacity to sequester additional atmospheric C might differ substantially in time and space. Hence, accurate and precise information on the complex spatio-temporal CO2 flux pattern is needed to evaluate the effects/benefits of new agricultural practices aiming towards increasing soil organic carbon.

To date, different approaches are used to measure and quantify CO2 flux dynamics of agricultural landscapes, such as e.g. eddy covariance, as well as manual and automatic chamber systems. However, all these methods fail to some extend in either accounting for small scale spatial heterogeneity (eddy covariance and automatic chambers) or short-term temporal variability (manual chambers). Although, automatic chambers are in principle capable to detect small-scale spatial differences of CO2 flux dynamics in a sufficient temporal resolution, these systems are usually limited to only a few spatial repetitions which is not sufficient to represent small scale soil heterogeneity such as present within the widespread hummocky ground moraine landscape of NE-Germany.

To overcome these challenges, we developed a novel robotic chamber system allowing to detect small-scale spatial heterogeneity and short-term temporal variability of CO2 (as well as CH4 and N2O) flux dynamics for a range of different fertilization and tillage management practices. The system is equipped with two canopy chambers, CR6 data logger, CDM-A116 analog multiplexer and multiple sensors to measure plant activity/biomass development in parallel. The measurements of the gaseous C exchange is performed by moving the system along the tracks with each chamber along one half of the gantry crane. Thus, each chamber measures 18 plots, out of 36 plots (2x3m; 12 per soil type) established in the study area.

Here, we present first CO2 flux measurement results (spring barley; 3 different soil types) using this novel system, to prove its overall accuracy and precision. Our results show clear small-scale/within field spatial pattern and short-term temporal dynamics regarding measured ecosystem respiration, net ecosystem exchange as well as derived gross primary productivity.
Antarctic-like temperature variations in the Tropical Andes recorded by glaciers during the last deglaciation (20 – 10 ka BP)
Authors: Martin Léo , Blard Pierre-Henri , Lavé Jérôme , Lupcker Maarten , Charreau Julien , Jomelli Vincent , Bourles Didier
Published: March 2020

The paleoclimatic changes that occurred in the Southern and Northern hemispheres during the last deglaciation are thought to have affected the continental tropical regions. However, the respective impact of North and Southern climatic changes in the tropics are still poorly understood. In the High Tropical Andes, the Antarctic Cold Reversal (ACR, 14.3-12.9 ka BP) was reported to be more represented than the Younger Dryas (12.9-11.7 ka BP) among morainic records. However, in the Altiplano basin (Bolivia), two cold periods of the North Hemisphere (Heinrich Stadial 1a (16.5-14.5 ka) and Younger Dryas) are synchronous with (i) major advances or stillstands of paleo-glaciers and with (ii) the highstands of the giant palaeo-lakes Tauca and Coipasa. Therefore, additional results are needed to disentangle between potential North and South Hemisphere climatic influence on the glacial dynamics in the region.

We present new Cosmic Ray Exposure (CRE) ages from glacial landforms of the Bolivian Andes that extend pre-existing datasets for four different sites spreading from 16 to 21°S. We reconstruct the Equilibrium Line Altitudes (ELA) associated with each moraine with the AAR method and use them in an inverse algorithm that combines both the palaeo-glaciers and palaeo-lake budgets to derive temperature and precipitation reconstructions. Our temperature reconstruction (ΔT vs. Present) shows a consistent trend through the four glacial sites with a progressive warming from ΔT= -5°C (17 ka BP) to –2.5°C (15-14.5 ka BP, at the end of the Tauca highstand). This is followed by a return to colder conditions, around -4°C, during the ACR (15.5-12.9 ka BP). The Coipasa highstand is coeval with another warming trend followed by ΔT stabilization at the onset of the Holocene (circa 10 ka BP), around -3°C. Precipitation is mainly characterized by increases during the lake highstands, modulated by the distance from the glacial sites to the center of the paleolakes that are moisture sources (recycling processes).

These new results highlight the decorrelation of the glacier dynamics to the temperature signal in regions that are characterized by high precipitation variability. They also provide a theoretical frame to explain how both regional and global forcings can imprint the paleo-glacial records. Our results strongly suggest that during the last deglaciation (20 – 10 ka BP), in the Tropical Andes, atmospheric temperatures follow the Antarctic variability, while precipitation is driven by the changes occurring in the Northern Hemisphere.
Seasonal variability of submicron aerosol acidity at a coastal site in the Eastern Mediterranean
Authors: Neroladaki Anna Maria , Stavroulas Iasonas , Tsiodra Irini , Myriokefalitakis Stelios , Nenes Anthanasios , Mihalopoulos Nikos , Kanakidou Maria
Published: March 2020

Aerosol acidity (pH) plays a significant role in the chemical behaviour of atmospheric particles, since it affects their composition and toxicity. This study investigates the seasonal variability of submicron particles acidity at the Finokalia atmospheric observatory in the eastern Mediterranean from February to December 2014. Direct measurements of aerosol pH are challenging and thus very rare. Therefore, aerosol pH is generally derived from thermodynamic model calculations. Submicron aerosol chemical composition data along with NH3 and HNO3 gas phase concentrations measured at Finokalia are here used in the thermodynamic model ISORROPIA-II in order to predict the aerosol pH. The predicted pH values show clear seasonality and the expected dependence on temperature and relative humidity. Submicron aerosols at Finokalia have been found to be acidic with an average pH values over the studied period of 1.77 ± 0.67, with the highest values occurring in winter and the lowest in summer and a winter to summer ratio of about 1.4.

We acknowledge support of this work by the project “PANhellenic infrastructure for Atmospheric Composition and climatE change” (MIS 5021516) which is implemented under the Action “Reinforcement of the Research and Innovation Infrastructure”, funded by the Operational Programme "Competitiveness, Entrepreneurship and Innovation" (NSRF 2014-2020) and co-financed by Greece and the European Union (European Regional Development Fund).
Towards a Sedimentary Carbon Stock Estimate for Scotland's EEZ: A Tiered Mapping Approach.
Authors: Austin William , Smeaton Craig
Published: March 2020

Coastal and shelf sediments trap and bury significant quantities carbon (Berner, 1982) and provide an conditions allowing for the long-term storage of carbon. Through burying this carbon these sediments potentially provide a climate mitigation services. Currently our understanding of the spatial distribution of C within the surficial sediments of  coastal and shelf seas is limited. Using Scotland’s EEZ as a natural laboratory in conjunction with the tiered seabed mapping methodology developed by Smeaton and Austin (2019), we show that coastal and shelf sediments are highly heterogenous in both sediment type and C content. The tiered approach utilised in this study is ideally suited to global applications where data availability may differ significantly. Improved spatial mapping of seabed C will provide policy makers with a new tool for the targeted management and protection of these globally important C stores.

Berner, R. A., 1982, Burial of organic carbon and pyrite sulfur in the modern ocean: Its geochemical and environmental significance.Am. J. Sci.282,451–473 (1982)

Smeaton, C. and Austin, W.E.N., 2019. Where’s the Carbon: Exploring the Spatial Heterogeneity of Sedimentary Carbon in Mid-Latitude Fjords. Frontiers in Earth Science, 7, p.269.
Large-Eddy Simulation of Extreme Updrafts in the Tropical Cyclone Inner Core
Authors: Wu Liguang
Published: March 2020

Extreme updrafts (stronger than 10 m s-1) have been observed in the tropical cyclone core region, which have profound implications to tropical cyclone intensification and structure change. Since extreme updrafts in the tropical cyclone are difficult to observe, their features and the associated mechanisms for formation and influences on tropical cyclones remain poorly understood. This study presents an analysis of extreme updrafts in a strong tropical cyclone that was simulated with the large-eddy simulation technique and the finest grid spacing of 37 meters. The simulated tropical cyclone experiences the vertical wind shear of about 5 m s-1 in a typical large-scale evironment in the western North Pacific. The simulated extreme updrafts in the inner core region exhibit the high frequency at the altitudes of ~ 750 m, 6.5 km and 13 km. The extreme updrafts in the inflow and outflow layers are closely associated with the Richardson Number of less than 0.25, indicating their relationship with severe turbulence caused by strong vertical wind shears. The extreme updrafts in the middle layer are associated with the strong convective activity. The details of the structures of the extreme updrafts are discussed.
Discharge and bathymetry estimations of rivers from altimetry and datasets by hybrid computational methods
Authors: Monnier Jerome , Larnier Kevin , Garambois Pierre-André
Published: March 2020

We present the Hierarchical Variational Discharge Inference (HiVDI) algorithm [1,2] and its capabilities to estimate the discharge and bathymetry of rivers from altimetry measurement, more particularly from the forthcoming SWOT space mission. The last version algorithm is based on hierarchical flow models and hybrid computational approaches : 1) a dedicated satellite-scale low-complexity model relating the discharge Q(x,t), the bathymetry b(x) and the friction parameter K [2]; 2) an advanced Variational Data Assimilation (VDA) formulation based on a relatively complete physics (Saint-Venant’s equations) [2,4] ; 3) deep neural networks based estimations obtained from recently enriched databases [1]. The resulting algorithm turns out to be robust and relatively accurate. Passed the assimilation of a hydrological cycle (~ 1 year variations, considered as a “learning period) the identified parameters (b(x), K) are identified; next given newly acquired satellite measurements, the low complexity model enables to estimate Q(x,t) in real-time [1,2].

Numerical results on numerous river datasets are analyzed in detail including for relatively complex flows and multi-satellite datasets [1,2,3].

References

[1] K. Larnier, J. Monnier. "Hybrid data assimilation - deep learning approaches to estimate rivers discharges from altimetry". Submitted.

[2] K. Larnier, J. Monnier, P.-A. Garambois, J. Verley. "River discharge and bathymetry estimations from SWOT altimetry measurements". Revised (nov. 2019).

[3] P.-A. Garambois, K. Larnier, J. Monnier, P. Finaud-Guyot, J. Verley, A. Montazem, S. Calmant. "Variational inference of effective channel and ungauged anabranching river discharge from multi-satellite water heights of different spatial sparsity". J. of Hydrology 2019.

[4] P. Brisset, J. Monnier, P.-A. Garambois, H. Roux. "On the assimilation of altimetry data in 1D Saint-Venant river models". Adv. Water Ress. 2018. 

[5] "DassFlow: Data Assimilation for Free Surface Flows", open-source computational software. INSA - IMT, CNRS, CNES, CS group. http://www.math.univ-toulouse.fr/DassFlow
Ancient sedimentary DNA reveals long-term impact of climate change on northern flora
Authors: Alsos Inger ,   ECOGEN and IceAGenT teams
Published: March 2020

Arctic and alpine species are disproportionally affected by climate change, and knowledge about their ability to survive or disperse is essential for their long-term conservation. Ancient sedimentary DNA (sedaDNA) has improved as a proxy for reconstructing past floras, and may now be applied in high throughput analyses. Our lab has analysed, or is in the process of analysing, sedaDNA from ~40 long (up to 26 000 years old) and 11 short (0-1000 years old) lake sediment cores from the Europe (Alps, Norway, Svalbard, Iceland, Polar Urals). Both general and site-specific patterns have emerged from these data. For example, the taxa recorded in sedaDNA often indicate a warmer climate than that which has been inferred based on pollen records; this is in concordance with macrofossil evidence. Also, the limits of past northern tree lines may have been underestimated based on pollen studies. Some heathland species, such as Vaccinium spp. and Empetrum, often show a time lag in arrival compared with other species with similar climatic requirements. Thus, despite the fact that they have berries and therefore are well adapted to long-distance dispersal by birds, our data show they are constrained from rapid responses to climate changes. Other patterns are site-specific. For example, we see a stepwise doubling of floristic richness from the Last Glacial Maximum to the Holocene in the Polar Urals, which is barely detectable in the pollen analyses. Further, the majority of taxa with a mainly arctic-alpine distributions survived the early-Holocene climate warming, when shrub and trees entered the region, probably due to a very heterogeneous landscape that allows co-existence of species with different requirements. In contrast, arctic-alpine taxa disappear from the catchment a subset of the lakes studied in North Norway after shrub and forest expansion. Linking this type of information to characteristics of these biogeographic regions may provide useful when planning for future nature reserves. In the near future, the combination of many sites, complete DNA reference libraries, and emerging molecular methods will allow for the tracking of individual species through time and space.
Core-mantle boundary flows obtained purely from Swarm secular variation gradient information
Authors: Whaler Kathy , Hammer Magnus , Finlay Chris , Olsen Nils
Published: March 2020

The Swarm constellation provides information on both along- and across-track magnetic field gradients. Spatial changes of the magnetic vector field elements are described by a magnetic field gradient tensor, whose elements and their uncertainties can be estimated using the Virtual Observatory (VO) concept, whereby data within a cylinder centred on the VO with axis perpendicular to the Earth’s surface are reduced to a central point at satellite altitude. Recent experiments have shown that analysing data collected over a 4 month window provides the best compromise between reducing bias from the way the satellite orbits sample each VO cylinder and preserving information on temporal changes of the field, and that the data provide spatial information sufficient to resolve 300 non-overlapping VOs. We invert annual first differences of the 5 independent gradient tensor elements (providing estimates of secular variation, SV, gradients) at these 300 VOs over the Swarm era for advective velocity at the core-mantle boundary, forcing the flow to have minimal acceleration while providing an adequate fit to the data. We obtain flows similar to those from previous SV inversions but purely from the gradient information. The resolution of the SV gradients is higher than that of the SV itself, resulting in a ~30% increase in the number of effective flow parameters; this is thought to be because the gradients are less affected by long period external signals that are difficult to remove from the data, resulting in an improved signal to noise ratio. Although very little temporal change in the flow is required to reproduce even rapid changes in the magnetic field, we are able to isolate some robust flow changes, in particular regarding changes in the azimuthal flow acceleration, associated with the geomagnetic impulse in the Pacific region in around 2016.
Monitoring the efficacy of Natural Flood Management structures on flow attenuation and flood risk reduction
Authors: Lockwood Tamsin , Freer Jim , Michaelides Katerina , Coxon Gemma , Richardson Tom , Brazier Richard , Thorne Ben , Webb Louise
Published: March 2020

Land use and management changes and landscape modifications, including urbanisation and agricultural intensification, have resulted in significant increases in flood risk across the UK in recent decades. To combat this, a shift towards catchment-based flood risk management has seen a marked rise in Natural Flood Management (NFM) schemes applied across the UK. These schemes largely represent mitigation strategies that work with natural processes to restore and augment hydrological and morphological catchment features for enhancing downstream flood resilience through the slowing, storing and filtering of runoff and flow. This has been implemented through the introduction of woody debris, afforestation of floodplains and runoff attenuation features. However, despite growing evidence highlighting their potential benefits, the function of these structures in the landscape and their effectiveness for flood risk reduction is still highly uncertain.

 

To address this knowledge gap, this study evaluates the effectiveness of a range of larger-scale floodplain and in-channel NFM features for flow attenuation and flood risk reduction.  To achieve this, a two-year field campaign was conducted in Somerset, South West England, involving the collection of continuous discharge, storage volume and local rainfall data at four sites in the Tone and Parrett catchments. The sites contained NFM structures including offline and online storage ponds and in-channel woody debris. Using these data, filling, storing and spilling capabilities were characterised through the utilisation of field-scale DEMs from Structure from Motion (SfM) and manual surveys. Storm events were separated, and key hydrograph characteristics analysed, to determine the effect of NFM structures on high flow events and the potential for flow attenuation.

 

The results indicate an increase in storage and flow attenuation as a result of the inclusion of NFM. Increases in flow lag time downstream of in-channel features were identified, relative to an upstream gauge. Longer recession limbs were also recorded downstream of storage ponds, illustrating the buffering influence of upstream structures and the consequential slowed water release downstream. Floodplain-based storage structures were found to only function optimally during the largest events, where pond filling could occur directly from the channel and flow is temporarily stored on the floodplain. These results will provide vital evidence for both local and national NFM applications.
Targeted erosion control measures: The backbone of soil-conserving cultivation
Authors: Ringler Gerald , Höfler Sarah , Reebs Felix , Gumpinger Clemens
Published: March 2020

The intensification of agriculture over the last 50 years together with a constant change in climatic conditions has resulted not least in a deterioration of the aquatic habitat due to sediment input and siltation in the upper reaches of Bavarian streams. Concerned about this development, the  Fisheries Association Bavaria has launched a project to investigate the main causes of erosion on agricultural land.

By comparing aerial photographs from the 1960s with current orthophotos, by means of a detailed GIS-analysis, the size of agricultural plots in five representative catchment areas was first investigated. In a further step, erosion modelling based on the Universal Soil Loss Equation (USLE) was implemented in two catchment areas.

The intersection of the digitalized land uses from the two time steps showed that despite an almost constant proportion of arable land in the catchment area, the length of the fields had been increased by a third on average and their extent had at least doubled, due to wide-ranging changes in the landscape structure.

By considering the soil loss in the 1960s, that under today's conditions, and by modelling scenarios with conserving farming technics and further-reaching retention measures, conclusions can be drawn as to which measures will be necessary in the future to enable effective soil and water protection.

The erosion modelling showed that the average long-term soil loss - as a result of the USLE - currently exceeds a value of 40 t/ha*a under conventional farming in vast areas of the arable land. Likewise, even with conservation tillage (no-till), isolated erosion spots of more than 20 t/ha*a occur. Since a simple change to soil-conserving cultivation (reduction of the cultivation factor C) will not be sufficient to prevent future erosion events (increased precipitation erosivity R) and constant soil loss, targeted measures (improvement of the erosion protection factor P) against soil erosion must be implemented. This includes nature-based retention measures as wetlands, buffer strips or green waterways. All of which will also help to tackle the upcoming impacts of the Climate crisis. The chosen model supports the localization of the source of erosion as well as the selection and implementation of targeted measures.
Increasing stable time step sizes in ice sheet modelling
Authors: Löfgren Andre , Ahlkrona Josefin
Published: March 2020

In order to understand the rate at which an ice sheet is losing mass one has to consider its dynamics. Ice is a very slow moving, highly viscous, non-newtonian fluid and as such is most accurately described by the full Stokes equation. Time dependence is taken into account by coupling the Stokes equation to the so called free surface equation, which describes how the free surface boundary of the ice sheet is advected due to the Stokes velocity field.

A problem with this system is that it is numerically quite unstable and has a very strict time step constraint, where very small time steps are needed in order to have a stable solver. This constitutes a severe limitation for making long term predictions as the expensive nonlinear Stokes equation has to be solved in each time step.

By adding an additional term to the weak form of the Stokes equation we achieve stability for time steps 10-20 times larger than without stabilization. This stabilization technique is straightforward to implement into existing code and does not result in significantly larger computation times or memory usage.