bluuebunny/crossref_metadata_2025 huggingface dataset:
Erosion and sediment enrichment ratio in volcanic soils
Authors: La Manna Ludmila , Mario Rostagno César , Tarabini Manuela , Gomez Federico , Navas Ana
Published: March 2020

Patagonian Andean region is widespread affected by soil degradation and erosion processes. The subhumid sector, which corresponds to the transition (ecotone) between the Andean forests and the Patagonian steppe, has suffered the highest human pressure and overgrazing, accelerating the soil erosion processes.

Near Esquel town (Subhumid sector of Chubut province, Argentina), where soils are mainly developed from volcanic ashes, erosion studies based on fallout radionuclides (Caesium-137) and simulated rainfalls were performed. Studies based on Caesium-137 showed that soil losses in the last 50 years were higher than 30 m3 ha-1 year-1 under different land uses.

Rainfall simulation experiments, carried out under the same conditions (Rain fall intensity: 100 mm h-1 for 30 minutes; Drop diameter: 2.5 mm; Drop velocity: 5.3 m s-1) showed that erosion rates are highly affected by land use. Potential erosion rates in degraded rangelands varied between 143 and 750 g m-2, depending on soil characteristics (such as texture and presence of non-crystalline materials), soil cover and slope. In mature exotic conifer afforestations, with soil completely covered by litter, soil erosion was negligible, varying between 0 and 10 g m-2. Erosion rates increased both in young afforestations with open canopies (8 a 44 g m-2), and in mature afforestations where fresh litter and duff layers were removed (35 a 200 g m-2).

In the different studied systems, soil losses involved not the detachment of individual particles, but of soil micro aggregates rich in organic matter. Sediments enrichment ratio was always higher than 1, varying between 1.2 and 1.8. These results show that the sediments were enriched with organic matter, as compared to the contributing soils, indicating its selective removal. The erosion studies performed evidence the high erodibility of volcanic soils when their cover is lost, and the close link between erosion and carbon losses in these systems.
Inferring controls on basal drag in the Amundsen Sea sector of Antarctica
Authors: Arthern Robert , Williams Rosie , Hogan Kelly , Brisbourne Alex , Smith Andrew , Jordan Tom
Published: March 2020

We consider a variety of ways that the basal drag that acts to resist the sliding of an ice sheet can be inferred from satellite observations, or from in situ observations. Three approaches are considered here. (1) use of inverse methods combined with large scale models of ice flow. (2) spectral analysis of basal topography combined with a theory of ice flow near small scale undulations, and (3) seismic methods that probe the physical characteristics of the subglacial sediment. Consideration is given to which sliding relationships are consistent with the available observations, and to identifying measurements that could help reduce ambiguity in sliding laws.
Numbers vs. Narratives: the importance of integrating social science perspectives in ocean sustainability research
Authors: Packer Helen , Held Mirjam
Published: March 2020

Many disciplines study the ocean and its uses from different perspectives. Recently, there has been a growing awareness about the inseparability of the social and ecological systems and that achieving sustainable use of ocean resources will require the integration of different types of knowledge and disciplines. In this presentation, we will draw from the experience of two early career interdisciplinary scientists to present examples of the role social sciences can play in achieving sustainable oceans management, how and why it should be integrated with other ocean disciplines. More specifically, we will present how a qualitative research approaches to understanding seafood sustainability governance and community/rights-based management makes an important contribution to sustainable ocean management. We conclude that to achieve ocean sustainability, which is a societal problem, we not only need numbers but also the social sciences and their narratives.
The NE-Atlantic challenge: where should we core and where should we conduct a wide-angle seismic survey?
Authors: Geoffroy Laurent
Published: March 2020

The Northeast Atlantic area presents new fundamental challenges in geodynamics, making it a superb international laboratory to develop new models and concepts that can be tested elsewhere. Among the most exciting challenges in this area is characterization of the different types of crust that may be encountered in oceanic realms. Viewing this area objectively, it appears that the classical distinction between oceanic and continental lithosphere is no longer adequate to interpret contemporary observations. This is a direct consequence of the huge input of magma into the lithosphere that has occurred at different stages of its evolution. Notably, we do not fully understand the true nature of the crust beneath Iceland and along the nearby continental margins and aseismic ridges (e.g., the GIFR). In particular, the classical distinctions made from linear magnetic anomalies (LMA) to distinguish oceanic and continental lithosphere is proven to not work. Massive magmatic-type accretion may occur together with continental thinning and stretching to generate symmetrical LMA over wide continental domains and give rise to erroneous interpretations as oceanic-type lithosphere. If part of the crust is inherited from former, albeit transformed, continental crust, this must also apply to the underlying mantle lithosphere. For example, old slabs may be trapped and reworked in the lithosphere and play major roles in its evolution. These new considerations have fundamental economic, political and scientific implications. It is now urgent to target and investigate the true nature of the crust in the NE-Atlantic, in particular seeking clues to the existence of continental material in specific areas. In my presentation I will make specific proposals.
Characterization of Equatorial Low Latitude Ionospheric Scintillation of GPS Signals: An E-POP Experiment
Authors: Mohandesi Ali , Knudsen David , Skone Susan
Published: March 2020

Ionospheric irregularities are a major error source in GNSS positioning and navigation as they affect trans-ionospheric signal propagation. They cause random, rapid fluctuations in the intensity and phase of the received signal, referred to as ionospheric scintillations. From a global point of view, GNSS signal scintillations are more severe and frequent in the equatorial region and during post-sunset hours. Characterizing irregularities that interfere most with navigation signals requires high-temporal resolution of measurements. In this work we utilize high-rate upward-looking measurements accomplished by the GAP RO receiver on CASSIOPE (Swarm Echo) satellite to study GPS signal scintillations and irregularities associated with them. This was done by reorienting CASSIOPE by approximately 90 degrees for short periods during November and December, 2019 while it passed through low-latitude region during post-sunset hours local time. High-rate GAP RO measurements provide a unique opportunity to investigate small-scale irregularities that are responsible for signal scintillations.
The response of Bonis Catchment in Calabria –Southern Italy to different management options under climate change scenarios.
Authors: Feki Mouna , Ravazzani Giovanni , Caloiero Tommaso , Pellicone Gaetano
Published: March 2020

Forests ecosystems provide several ecosystem services among which the regulation of the hydrological cycle. These ecosystems are exposed to different forms of disturbances induced by human activities, management strategies, and climate change. The objective of INNOMED project, for the Italian case study, is to understand the response of forest to different silvicultural practices under climate change conditions. The study site is the the Bonis catchment located in the mountain area of Sila Greca (39°25’15’’N, 16°12’38’’W), in the Calabria region (southern Italy). This small catchment has a surface of 1.39 km2 and a mean elevation of 1131 m above sea level. Almost 93% of the total area is covered by forest stand, dominated by about 50-year-old Calabrian pine (Pinus laricio Poiret) forests. In order to simulate the response of the catchment to different climate and management scenarios, FEST-WB distributed hydrological model was used. Within the framework of this project, FEST-FOREST module has been implemented in order to consider vegetation dynamics interactions with the hydrological response of the watershed. Since 1986, the basin was monitored through the installation of different instruments. Rainfall was measured by three rain gauges (with a tipping bucket) together with temperature that were measured at three different meteorological stations. In May 2003, a tower for measurement of eddy fluxes was installed at an altitude of 1100 m a.s.l, on a 54 years old plantation of Laricio pine which allowed monitoring of other parameters. Runoff was measured at the outlet of the catchment using a gauging structure. These data were used for the calibration and validation of the model before being implemented for future scenarios simulations. The results of these simulations delivered the potential impacts and the vulnerability of the Bonis catchment to different scenarios. These outcomes provide for the stakeholders a scientifically based and solid information for a sustainable management of the catchment.
On the astronomical forcing of simple conceptual ice age models
Authors: Leloup Gaëlle , Paillard Didier
Published: March 2020

Variations of the Earth’s orbital parameters are known to pace the ice volume variations of the last million year [1], even if the precise mechanisms remain unknown.
Several conceptual models have been used to try to better understand the connection between ice-sheet changes and the astronomical forcing. An often overlooked question is to decide which astronomical forcing can best explain the observed cycles.

A rather traditional practice was to use the insolation at a some specific day of the year, for instance at mid-july [2] or at the june solstice [3].
But it was also suggested that the integrated forcing above some given threshold could be a better alternative [4]. In a more recent paper, Tzedakis et al. [5] have shown that simple rules, based on the original Milankovitch forcing or caloric seasons, could also be used to explain the timing of ice ages.
Here we adapt and simplify the conceptual model of Parrenin and Paillard 2003 [6], to first reduce the set of parameters.
Like in the original conceptual model from [6], this simplified conceptual model is based on climate oscillations between two states: glaciation and deglaciation. It switches to one another when crossing a defined threshold. While the triggering of glaciations is only triggered by orbital parameters, the triggering of deglaciations is triggered by a combination of orbital parameters and ice volume.
Then, we apply the different possible forcings listed above and we try to adapt the model parameters to reproduce the ice volume record, at least in a qualitative way. This allows us to discuss which kind of astronomical forcing better explains the Quaternary ice ages, in the context of such simple threshold-based models.

[1] Variations in the Earth's Orbit: Pacemaker of the Ice Ages, Hays et al., 1976, Science 

[2] Modeling the Climatic Response to Orbital Variations, Imbrie and Imbrie, 1980, Science 

[3] The timing of Pleistocene glaciations from a simple multiple-state climate model, Paillard, 1998, Nature

[4] Early Pleistocene Glacial Cycles and the Integrated Summer Insolation Forcing, Huybers et al., 2006, Science

[5] A simple rule to determine which insolation cycles lead to interglacials, Tzedakis et al., 2017, Nature

[6] Amplitude and phase of glacial cycles from a conceptual model, Parrenin Paillard, 2003, EPSL.
Visual preference for treatment of bare land on hillside
Authors: Chen Jinn-Chyi , Chang Ya-Chun , Huang Wen-Shun
Published: March 2020

Bare land is common on hillsides and may occur due to landslides, cultivated lands, or engineering construction sites. The purpose of this study is to analyze the visual preference of treatment of bare land on hillside. The treatment methods for bare land are classified into ecological engineering, non-ecological engineering, and natural recovery or vegetation. For this study, first, several images of areas in North Taiwan that experienced landslides or engineering construction were collected, including Daan and Shilin districts in Taipei city, Wugu, Shiding and Tamsui districts in New Taipei city, and Fuxing district in Taoyuan city. Then, Photoshop software was used for image processing and for calculation of percentage of vegetation cover on the bare land, i.e., the green looking ratio (GR). Furthermore, a questionnaire survey was conducted to investigate the visual preference (P) and the cognitive factor of an image associated with the GR. Three cognitive factors, consistency (C), vividness (V), and naturalness (N), were used for the survey. A total of 131 effective questionnaires were received from survey respondents and the Likert scale was used to rate the degree of visual preference and cognition. The rating values ranged from 1 to 5. The results show that a higher N, V, and C was preferred by viewers when the bare land was covered with vegetation or high GR. The factors C, V, N, and P for treatment of bare land using ecological engineering method are higher than those using non-ecological engineering. The adopted natural or flexible methods to treat bare land prompt visual preferences from viewers and can provide important references for landscape engineering design.
Seismological Observations of the Seasonal Rain and Aquifer Induced Seismicity in Southeastern Brazil
Authors: Convers Jaime A. , Assumpção Marcelo , Barbosa Jose R.
Published: March 2020

We update our analysis on the ongoing seasonal induced microseismic activity in southeastern Brazil, in the interior of the state of Sao Paulo.  This is an area that not evidenced any active seismicity before 2016. We monitor this phenomenon as it is similar to other episodes of seasonal seismicity in other regions of Brazil, under similar aquifer and host rock conditions, commonly associated with those of the Parana Basin. 

This induced seismicity is seemingly triggered yearly during the high-rain season in Southeast Brazil, between December and May, and ceases as soon as the heavy rain season ends each year.  In these periods of increased precipitation during the annual onset of seismicity, we have found more than 1500 seismic events of magnitudes up to M2.0 in since 2017, after we deployed seismic stations in this area. Using phase weighing earthquake locations algorithms, we examine the clustering of the seismicity around recently drilled water wells, and seismicity rate changes, as it is modified by variations in the precipitation.

We perform full moment tensor analysis when possible to find the seismic activity is not only clustering horizontally, but at depth as well.  We identify two main regions where events are more frequently occurring and have mostly prevalent sub-horizontal dipping planes: The shallow events between 100 and 200 m and from 600 to 700 m depth. 

This phenomenon is facilitated mainly by the inadequate water well perforation practices in the region. Uncased water wells promote the transport of both rainwater and groundwater from upper to lower aquifers during higher precipitation months. The stress conditions of the fractured basaltic rock inside the confined aquifers are affected by the intrusion and percolation of significant amounts of water, which produce pore-pressure changes inside the host rock, and facilitates stress release though the microseisms.  This implies that the confined aquifer characteristics of intermittent sandstone layers and fractured basalt rocks from the Parana Basin condition the characteristics of the seismicity occurring in this region of Brazil. 
Forest recovery and its driving forces in karst areas of southwest China
Authors: Guo Xiaona , Chen Ruishan , Li Qiang , Meadows Michael E. , Pan Zhenzhen
Published: March 2020

Abstract: Globally, the loss of forest is of great concern as forest plays many key roles in the earth system, for example, it contributes to biogeochemical cycles and rural livelihoods. Forest could provide ecosystem services such as soil retention and flood regulation and is especially critical in mountain environments. Deforestation in such regions further results in carbon emission and biodiversity loss and may reduce agricultural productivity and increase the poverty rate. In China, recognition of these problems has prompted a series of ecological construction programs, including “Returning Farmland to Forest” (RFF), which advocates stopping farming on sloping land that is prone to soil erosion and promotes afforestation and recovery of forest vegetation and was initially implemented in 1999. The program has been widely applied in Guizhou Province, a typical fragile karst mountain area of southwest China. There is, however, a lack of knowledge of the effectiveness of the RFF policy, and the relative roles played by possible factors that lead to forest change. Here we analyze the pattern and process of forest change in the karst mountain regions of Guizhou province between 1980 and 2018 and evaluate how RFF and other driving forces contribute to these changes. Based on a temporal sequence of satellite images, we develop a Markov model to examine the forest change, and found that most of the forests grow on the slopes of 15-25°, the forest cover has increased by 1,410 km2 between 1980 and 2019, and 36% of cropland in Guizhou province has been converted to forest since 1980. Out of nine municipalities in the province, the most significant increases in forest cover occurs in Qiandongnan, which accounts for 20% (583 km2) of the increased area. we also found that the RFF program has had a marked positive impact on forest cover and has also improved hydrothermal conditions in the region. However, population, GDP, and traffic accessibility have a negative impact on forest cover. Climate factors appear to have the least impact on forest change during the period of 1980 to 2018. The findings offer useful information for resource managers to engage in forest protection, deforestation prevention, and ecological restoration in regions with similar conditions.    

KEYWORDS: forest; restoration; RFF; GDP; karst areas
Screening of plants of different species and functional groups for phytomining of rare earth elements in soil
Authors: Okoroafor Precious , Wiche Oliver
Published: March 2020

To significantly contribute to the available information on potentials of different plants species for use in phytomining of  Rare Earth Elements(REEs) , a screening experiment was conducted to directly compare at once 8 plant species belonging to two functional groups (herbs and grasses), grown on a soil with high  REEs concentrations. The plants were grown for 10 weeks on potted soils, each containing 2kg of soil.  The plants evaluated are Fagopyrum esculentum, Cannabis sativa, Brassica napus and Sinapis alba for the herbaceous species and Sorghum bicolor, Zea mays, Avena sativa and Festuca arundinacea for the grass species. Concentrations of the four REEs namely Cerium (Ce), Lanthanum (La), Neodymium (Nd) and Yttrium (Y) and amount/content of each REE contained in the species investigated were determined and the data obtained were subjected to the statistical analysis Multivariate Analysis of Variance to identify differences that exist between species, within and between functional groups. Results show that the differences observed in amount of each of the REEs phytomined by the different grass species are statistically insignificant. Contrastingly, significant differences exist between the concentrations and content of each of the REEs between the herbaceous species, with F. esculentum significantly showing higher potential for use in phytomining compared to the rest of the herbaceous species. Results from statistical comparison of all species shows that F. esculentum is the candidate that showed more potential for use in phytomining , with C. sativa also being the next  specie with high potential for phytomining aside from F.esculentum  when compared to the rest of the species investigated. Functional groups were compared, and results showed that the herbaceous specie have a significantly higher potential for use in phytomining of REEs compared to grass species. Results from this experiment contributes to existing knowledge on potentials of different plant species for use in phytomining and suggest possible candidates in comparison to others, for use in experiments that seek to improve the chances of using plants as an eco-friendly alternative to conventional mining of rare earth elements in commercial quantities.
Controls on the lateral channel migration rate of braided alluvial channel systems
Authors: Bufe Aaron , Turowski Jens , Burbank Douglas , Paola Chris , Wickert Andrew , Tofelde Stefanie
Published: March 2020

Lateral movements of alluvial river channels control the extent and reworking rates of alluvial fans, floodplains, deltas, and alluvial sections of bedrock rivers. These lateral movements can occur by gradual channel migration or by sudden changes in channel position (avulsions). Whereas models exist for rates of river avulsion, we lack a detailed understanding of the rates of lateral channel migration on the scale of a channel belt. Here we develop, for the first time, an expression that describes the lateral migration rate of braided alluvial channels in non-cohesive sediment. On the basis of photographic and topographic data from laboratory experiments of braided channels performed under constant external boundary conditions, we first explore the impact of autogenic variations of the channel-system geometry (i.e., channel-bank heights, water depths, channel-system width, and channel slope) on channel-migration rates. In agreement with theoretical expectations, we find that, under such constant boundary conditions, lateral channel-migration rates scale inversely with the channel-bank height. Furthermore, when changes in channel-bank heights are accounted for, lateral migration rates appear independent of channel slope, channel-system width, and water depth. These constraints allow us to derive two dimensionally consistent expressions for lateral channel-migration rates under different boundary conditions. We find that migration rates are strongly sensitive to channel-bank heights and water discharges and more weakly sensitive to sediment discharges in braided equilibrium channel systems. In addition, the strong dependence of lateral migration rates on channel-bank heights implies that external perturbations (for example, perturbations of sediment and water discharges) that modulate the depth of channel incision and can indirectly affect lateral channel-migration rates.
Primary productivity, deoxygenation, and the Gulliver-absence effect determine bivalve body size following the end-Permian mass extinction
Authors: Tietje Melanie , Foster William J. , Gliwa Jana , Lembke Clara , Pugh Autumn , Hofmann Richard , Varela Sara , Foster Louise C. , Korn Dieter , Aberhan Martin
Published: March 2020

 The impact of mass extinctions on the body sizes of animals has received considerable attention and debate, as to whether the reduced size of post-extinction organisms is due to the selective extinction of large species, absence of large species as a stochastic effect of low-diversity faunas, or a size decrease within surviving genera and species. Here, we investigated the body sizes of bivalves following the end-Permian mass extinction event and show that the shell size increase of bivalve genera was driven by both evolutionary and ecophenotypic responses. First, some genera show significant increases in body size with the evolution of new species. Further, the same genera record significant within-species increases in average and maximum body size into the late Induan, indicating that ecophenotypic changes were also involved on long-term body size trends. These increases are associated with invigorated ocean circulation, improved oxygenation of the seafloor, and probably increased food supply.
Latest scientific and technical evolutions in the Crocus snowpack model
Authors: Lafaysse Matthieu , Dumont Marie , Nheili Rafife , Viallon-Galinier Léo , Carmagnola Carlo , Cluzet Bertrand , Fructus Mathieu , Hagenmuller Pascal , Morin Samuel , Spandre Pierre , Tuzet François , Vionnet Vincent
Published: March 2020

This contribution presents an overview of the last stable release of the Crocus detailed snowpack model in the SURFEX opensource modelling platform. It gathers numerous recent scientific and technical developments in a common code version. An explicit representation of the evolution of light absorbing particles mass in snow (e.g. black carbon, mineral dust) allows representing their impact on solar radiation absorption in the snowpack in the visible and near-infrared spectrum through the TARTES optical scheme, and the consequences on all snowpack properties. Crocus is now coupled to the MEB (Multiple Energy Balance) vegetation scheme and can therefore be applied on forested areas. A module of snow management including grooming and snow making can also be optionally activated to simulate the snowpack on ski slopes. Developments used in the French operational system in support of avalanche hazard forecasting were also fully integrated in SURFEX: the SYTRON module for snow erosion and accumulation by the wind and the expert system MEPRA which analyses the mechanical stability of the simulated snowpacks. Finally, an ensemble multiphysics version of the model (ESCROC) was also developed by implementing from 2 to 4 parameterizations from the literature for each physical process represented by an uncertain empirical parameterization. The different combinations enable the quantification of simulations uncertainty required in various applications: future projections of snow cover; sensitivity analyses of a given process ; data assimilation of snow observations. Crocus and ESCROC are included in the ESM-SnowMIP model intercomparison and exhibit a robust skill in various climates and environments. Several running-time optimizations were also implemented in the latest release. We present an overview of the current numerical cost with a comparison to more classical snow schemes used in NWP and climate model applications. The code is provided through a git repository and with a simple visualization software to help users to display snowpack internal properties at local scale. On-going works are focused on the implementation of new data assimilation algorithms well suited to the numerical specificities of this scheme. An externalized version for coupling with other surface schemes is currently under development.
Mean-state dependence of future tropical-Atlantic sector climate projections
Authors: Park Wonsun , Latif Mojib , Imbol Nkwinkwa Njouodo Arielle Stela
Published: March 2020

Mean state and internal variability in the tropics are crucially linked to air-sea interactions. State-of-the-art climate models exhibit long-standing problems not only in simulating tropical mean climate, such as too cold sea surface temperature (SST) over the central tropical Pacific and too warm SST over the eastern tropical Pacific and Atlantic, but also with respect to seasonal and longer variability. These biases question the credibility of future climate projections with the models, and it has not been shown to date whether or how such SST biases affect the projections. Here we focus on the tropical Atlantic (TA) and investigate how the mean state influences climate projections over the region.

We use two versions of the Kiel Climate Model (KCM) in global warming simulations, in which only atmosphere model resolution differs: one version carries ECHAM5 with a horizontal resolution of T42 (~2.8°) and 31 vertical levels, and the other ECHAM5 with a horizontal resolution of T255 (~0.47°) and 62 levels. Although only the atmospheric resolutions differ, the two KCM versions exhibit very different mean states over the tropical TA, with the higher-resolution version, among others, featuring much reduced warm SST bias over the eastern basin.

The response to increasing atmospheric carbon dioxide levels is found to be sensitive to the mean state. The model employing high atmospheric resolution and featuring a small SST bias projects an eastward-amplified SST warming over the TA, consistent with the pattern of interannual SST variability simulated under present-day conditions and in line with the observed SST trends since the mid-20th century. The model employing low-resolution and exhibiting a large SST bias projects more uniform SST change. Atmospheric changes also vastly differ among the two model versions.

Analysis of models participating in the Coupled Model Intercomparison Project Phase 5 (CMIP5) support the KCM’s results: models with small SST bias project stronger warming over the eastern TA, while models with large SST bias either project uniform warming across the equator or largest warming in the west. This study suggests that reducing model bias may enhance global warming projections over the TA sector.
Contribution of lateral terrestrial water flow to precipitation – A WRF-Hydro ensemble analysis and continental evaporation tagging for Europe
Authors: Arnault Joel , Fersch Benjamin , Rummler Thomas , Zhang Zhenyu , Wei Jianhui , Quenum Mayeul , Graf Maximilian , Laux Patrick , Kunstmann Harald
Published: March 2020

Land-atmosphere feedback processes are key components of the Earth climate system. In general, it is questionable to which extend the state of the land surface feeds back to the state of the atmosphere. This question can be addressed with a coupled land surface – atmospheric model, and the realism of the simulated feedbacks can be evaluated with a model-to-observation comparison. This study investigates the particular case of the process chain linking lateral terrestrial water flow, soil moisture, surface evaporation and precipitation. The focus is on summer precipitation in the European region. The study period is set to four months in June-September 2008. The tool to conduct this study is the coupled atmospheric – hydrological model WRF-Hydro, which allows surface and subsurface water routing. For the setup of the atmospheric part, a horizontal grid of 700x500 grid points with a grid spacing of 5 km, that is covering an area of 3500 km x 2500 km, and 50 vertical levels up to 10 hPa is chosen. For the setup of the land water routing, a horizontal grid of 14000x10000 grid points with a grid spacing of 250 m and 4 soil layers down to 2 m depth is chosen. The employed model version includes a surface evaporation tagging procedure in order to quantify the fraction of European precipitation originating from evaporation from all over the European continent. The method consists of generating a set of WRF-Hydro simulations with and without land water routing by using random realizations of the stochastic kinetic energy backscatter scheme, and assess the impact of lateral terrestrial water flow on precipitation with the daily gridded observational dataset for precipitation in Europe (E-OBS). An ensemble size of twenty members is used to disentangle the contribution of two processes responsible for precipitation differences between WRF-Hydro simulations with and without land water routing, namely the changes in surface evaporation and the atmosphere chaotic behavior. It is found that the consideration of lateral terrestrial water flow increases the amount of summer precipitation through enhanced surface evaporation up to 10%, which reduces the bias to E-OBS.
Palynology as a tool for the knowledge on the millennial human impact and land management in the central Mediterranean
Authors: Mercuri Anna Maria , Florenzano Assunta
Published: March 2020

Ancient land management is inherited and at the base of the current landscapes and must be known to facilitate a sustainable land development for the future. Understanding past land-use systems is helpful for evaluating the current and future state of both biological and physical environments, and for disentangling the role of people in shaping current landscapes. Many different perspectives are involved in reconstructing the cultural impact on the environment. Palynology has great potentiality for environmental and palaeoethnobotanical purposes, with the study of high-resolution sequences formed under natural and anthropic (cultural) forces. Pollen data are fruitfully used to reconstruct land transformations in a diachronic palaeoecological perspective. For example, palynological records from central Mediterranean archaeological sites showed evidence of land uses and evolution of agrarian systems from Neolithic to Bronze Age, allowing a comparative view of the long-term changes in the land footprint of ancient Mediterranean societies. In this study we report on the level of detail on land management provided by palynological research from archaeological sites of Greek Basilicata (south Italy) and Roman Tuscany (central Italy). The local land use types and diﬀerent management strategies inferred from palynology provide an important contribution to the knowledge of land development and implications for a sustainable soil management in these regions.

 
Primary productivity dynamics in the northeastern Bay of Bengal over the last 26,000 years
Authors: Zhou Xinquan , Duchamp-Alphonse Stéphanie , Kageyama Masa , Bassinot Franck , Beaufort Luc , Colin Christophe
Published: March 2020

Paleo-records of primary productivity (PP) changes from the Arabian Sea (AS) have revealed the major influence of monsoon-wind intensity in controlling productivity variations at different timescales, through mixed-layer dynamics and upwelling activity. Much less is known, however, about past changes in paleo-PP in the Bay of Bengal (BoB).

       In the present study, we have reconstructed PP over the last 26,000 years from a sediment core located on the northeastern (NE-) BoB. Paleo-PP was estimated by a PP empirical equation using the relative abundance of Florisphaera profunda, a deep dwelling coccolithophore that develops in the lower euphotic zone. Our record does not reveal any obvious difference of PP between the Last Glacial Maximum (LGM) and the late Holocene, but strong oscillations characterize the deglaciation. Our NE-BoB record is anti-phased to PP records in the AS, and positively correlated to surface seawater salinity (SSS) changes reconstructed from the same core since the LGM. We propose that the strong correlation to salinity variations reflects the role of salinity-stratification related to monsoon precipitation on PP at both orbital- and millennial-scales. Outputs of a climatic transient simulation (TraCE-21) and runs obtained with the Earth System Model IPSL-CM5 support the above interpretation of a strong control of past PP variations by local hydrological changes in the NE-BoB. Our data also highlight the potential teleconnection of the Atlantic Meridional Overturning Circulation strength and Indian Monsoon intensity during the deglaciation.
Coupling the Parallel Ice Sheet Model with the Modular Ocean Model via an Antarctic ice-shelf cavity module
Authors: Kreuzer Moritz , Reese Ronja , Huiskamp Willem , Petri Stefan , Winkelmann Ricarda
Published: March 2020

Ocean-ice shelf interactions are the main drivers for the current mass loss from the Antarctic Ice Sheet. Recent studies have shown that increased continental meltwater input can enhance discharge through ice-ocean feedbacks. This raises the need for interactive modelling between ocean and ice-sheet systems to assess the consequences of additional freshwater input on the Antarctic region and beyond. While high-resolution simulations (1/4 degree or greater) can resolve detailed interactions between the ocean and ice shelf, the computational costs make them applicable only for regional studies or decadal to centennial time scales. In this study we present a framework for coupling a coarse resolution ocean model (MOM) to the Parallel Ice Sheet Model (PISM) via the Potsdam Ice-shelf Cavity mOdel (PICO). The intermediate model PICO approximates the overturning circulation in ice shelf cavities and includes ice-ocean boundary layer physics. We present this offline coupling approach and discuss the fluxes exchanged between the distinct model runs as well as energy and mass conservation. Using this flexible and computationally efficient framework, feedbacks between the ice and ocean can be analysed on a global spatial scale and paleoclimate time-scales.

 
A new scenario logic for the Paris Agreement long-term temperature goal
Authors: Rogelj Joeri , Huppmann Daniel , Krey Volker , Riahi Keywan , Clarke Leon , Gidden Matthew , Nicholls Zebedee , Meinshausen Malte
Published: March 2020

To understand how global warming can be kept well-below 2°C and even 1.5°C, climate policy uses scenarios that describe how society could transform in order to reduce its greenhouse gas emissions. Such scenario are typically created with integrated assessment models that include a representation of the economy, and the energy, land-use, and industrial system. However, current climate change scenarios have a key weakness in that they typically focus on reaching specific climate goals in 2100 only.

This choice results in risky pathways that delay action and seemingly inevitably rely on large quantities of carbon-dioxide removal after mid-century. Here we propose a framework that more closely reflects the intentions of the UN Paris Agreement. It focusses on reaching a peak in global warming with either stabilisation or reversal thereafter. This approach provides a critical extension of the widely used Shared Socioecononomic Pathways (SSP) framework and reveals a more diverse picture: an inevitable transition period of aggressive near-term climate action to reach carbon neutrality can be followed by a variety of long-term states. It allows policymakers to explicitly consider near-term climate strategies in the context of intergenerational equity and long-term sustainability.
Development of combined measurement method for methane, nitrous oxide and carbon dioxide without gas cylinder by gas chromatography
Authors: Sudo Shigeto
Published: March 2020

Greenhouse gas emission from agricultural ecosystems are one of major environmental issue, recently. Our research aim is improving greenhouse gas flux measurement method precisely, inexpensively and automatically in agricultural ecosystems. Measurement method for CO2, CH4 and N2O simultaneous analysis (3GHG-GC) was firstly launched in 2005 followed by automatic gas sampling system (AGSS) in 2006, automatic injector for GC (RoVi) in 2013 and nitrogen generation system from compressed air for precise GC analysis in 2011, respectively. 3GHG-GC was recently further improved that the carrier gas of this method was changed from helium to nitrogen or argon to meet global requirement to save helium consumption. In "3GHG-GC", 3 stages of packed separation column using Porapak Q (Waters Co. Ltd. USA) and Unibeads C (GL Science Co. Ltd. Japan). Shimadzu GC-2014 gas chromatograph equipped with thermal conductivity detector (TCD), flame ionization detector (FID) and electron capture detector (ECD). The carrier gas was purified nitrogen generated by compressed air. The impurity of methane in the carrier nitrogen was eliminated by catalytic chemical treatment to measure precise atmospheric level of CH4. Finally the system "3GHG-GC" achieved three gas combined precise measurement with standard error of  within 1% without gas cylinder for carrier gases.  
Underground seasonal storage of gas: testing numerical modelling tools with application to i) a deep aquifer-layer, and ii) salt caverns.
Authors: Silverii Francesca , Al-Halbouni Djamil , Stefanova Vassileva Magdalena , Richter Gudrun , Wang Rongjiang , Gonzalez Cansado Borja , Hainzl Sebastian , Dahm Torsten , Maccaferri Francesco
Published: March 2020

Within the framework of the SECURE project, we test modeling techniques used for natural geothermal and volcanic reservoirs and apply them to anthropic underground gas storage facilities. These systems indeed share similar mechanics and physical properties, however gas reservoirs are often extensively monitored, and better imaged. In order to manage fluctuations between gas supply and demand, natural gas can be temporarily stored in different underground storage facilities, such as depleted gas/oil fields, natural aquifers, and salt cavern formations. When properly monitored during storage and withdrawal (production) of gas, these systems provide a unique opportunity to investigate how reservoirs evolve at different time scales, modify the surrounding stress state, produce deformation coupled with diffusion processes, and possibly induce/trigger earthquakes on nearby faults.

In the first case study we addressed within the framework of SECURE project, we take advantage of well constrained reservoir geometry and physical parameters, records of gas injection/production rates, pore pressure variations, and a local seismic catalog at a gas reservoir in Spain. We implement a poro-elastic model to simulate pressure temporal variations, estimate related stress-state variations, and study eventual relationship with small recorded seismic events. The model is based the software POEL by Wang et al., (2003), a semi-analytical physics-based numerical scheme which allows the computation of transient and steady-state solutions in response to pore-pressure variations. Being 2D axisymmetric, POEL drastically simplify the geometry of the reservoir, but it is particularly suitable to link observables such as pressure variations within the reservoir with the physical/mechanical processes occurring in the surroundings.

In the second case study we address the stability condition for salt caverns which has been excavated for salt mining purposes. We make use of 2D discrete-element geomechanical models to compare numerical simulation results with field observations in terms of surface subsidence. With this numerical model we consider different pressure conditions for the fluid (brine) filling the cavity, and return different scenarios for the stability of a salt cavern. Such modeling effort aims at improving our understanding of middle-to-long term stability conditions, for those cavities that have been dismissed after anthropic operations such as salt extraction, but also seasonal gas storage.
Ocean dynamics and climate during a Neoproterozoic snowball Earth and its aftermath as simulated in a coupled Earth system model
Authors: Ramme Lennart , Marotzke Jochem
Published: March 2020

The Neoproterozoic glaciations, referred to as snowball Earth periods, describe the most extreme transition from a very cold climate to a state of strong greenhouse effect. Atmospheric CO2 concentrations are rising during the snowball, due to the shutdown of oceanic and terrestrial carbon sinks, until a tipping point is reached and a rapid deglaciation sets in. Subsequently, a warm and completely ice-free climate under very high CO2 concentrations develops. We show first results of simulations using a coupled atmosphere-ocean general circulation model covering the initiation, as well as the melting of the Marinoan snowball Earth (645 – 635 My ago) and the greenhouse climate in its aftermath. CO2 concentrations are decreased to initiate a global glaciation and then increased again in order to melt the snowball Earth. As soon as a certain CO2 threshold is reached, sea-ice melts rapidly, reaching a completely ice-free ocean after only one hundred years, in our model without land glaciers. The ocean becomes strongly stratified, because at the surface the freshwater from the sea-ice melt is warming up quickly, whereas the deeper ocean remains cold and salty. Ocean surface currents return to their pre-snowball behavior soon after the melt, but destratification is slow. The largest mixed layer depths of up to 500 m are reached in the mid latitudes of the winter hemisphere. We compare the climate before and after the snowball state and estimate the time needed for destratification.
First application of low-cost eddy covariance for CO2 fluxes over agroforestry
Authors: van Ramshorst Justus , Markwitz Christian , Hill Timothy , Clement Robert , Knohl Alexander , Siebicke Lukas
Published: March 2020

Agroforestry is a combination of monoculture agriculture and trees. Studies of net ecosystem exchange of CO2 (NEE) of agroforestry systems are rare, in comparison to the extensive studies of NEE of agricultural systems (croplands and grasslands). Agroforestry has been shown to alter the microclimate, productivity, and nutrient and water usage – as compared to standard agricultural practise. The, potentially, higher carbon sequestration of agroforestry, relative to monoculture systems, provides an interesting option for mitigating climate change, highlighting the need for improved study of agroforestry systems. The current study, as part of the SIGNAL (sustainable intensification of agriculture through agroforestry) project, investigates NEE of agroforestry compared to that of monoculture agriculture. The study employs paired comparisons of flux measurements above agroforestry and monoculture agronomy, replicated at five locations across Germany. Fluxes are measured, using innovative low-cost CO2 eddy covariance sensors (slow response Vaisala GMP343 IRGA with custom made housing), which have been successfully used in a study over grassland. Continuous data series from mid-summer until winter 2019 show that both systems acted as a sink with comparable fluxes during summer. The diurnal CO2 cycle and the response to management activities are distinguishable and in autumn preliminary results suggest a small difference in fluxes between the two systems. The low-cost eddy covariance system is able to capture the turbulence and to measure the CO2 flux over the agroforestry and monoculture agricultural system. We aim to further improve the quality of the CO2 fluxes, by adapting post-processing software to better estimate the difference in carbon uptake between the agroforestry and monoculture systems.
Environmental controls on the magnetic properties of Upper Jurassic black shales on the Norwegian shelf
Authors: Kimerud Jonas Kristensen , Felix Maarten
Published: March 2020

This project examines organic rich black shales from the Upper Jurassic on the Norwegian shelf. The aim is to investigate the relationship between the depositional environment as determined from facies descriptions and the magnetic properties of the black shale. An additional aim is to relate cyclicity in the magnetic measurements to the Milankovitch cycles using time series analysis techniques. Cores from four different location on the Norwegian shelf were investigated using sedimentological description, facies analysis, and measuring of bulk magnetic susceptibility. The cores were drilled in the Skagerrak Region in the North Sea (core 13/01-U-01), Møre-Trøndelag Region of the Norwegian Sea (core 6307/07-U-03 A), Lofoten Region of the Norwegian Sea (core 6814/04-U-02), and the Nordkapp Basin in the NE Barents Sea (core 7230/05-U-02).

Based on preliminary results from the sedimentological description and facies analysis, the sediments were separated into facies: (1) massive black mudstone, (2) siderite cemented mudstone, (3) lenticular laminated sandy mudstone, (4) flaser laminated muddy sandstone with silt clasts, (5) heavily bioturbated silty sandstone, and (6) sandstone. Deposits like high-density turbidites, debrites and slump deposits, as well as post depositional processes like bioturbation, pyrite- and siderite-cementation were found in the cores. Deposits from mass movements can be thick, but they are deposited over a short time interval. It is therefore important to remove the mass movement deposits in the cyclostratigraphic analysis. The high iron content in the siderite and pyrite cemented deposits must be taken into account in regard to the magnetic susceptibility measurements. The magnetic susceptibility data will be used to correlate the cores in the homogeneous black shale sections.