bluuebunny/crossref_metadata_2025 huggingface dataset:
Local high-energy particles measurements for detecting primary cosmic-ray variations: application for soil moisture estimation
Authors: Stevanato Luca , Baroni Gabriele , Fontana Cristiano , Lunardon Marcello , Moretto Sandra , Schattan Paul
Published: March 2020

In the last decade the measurement of secondary cosmic ray neutrons has been established as a unique approach for intermediate scale observation of land surface hydrogen pools. Originally developed for soil moisture measurements, it has shown also promising applications for snow, biomass and canopy interception. The approach relies on the correlation between natural neutron background as created by cosmic-ray fluxes and local hydrogen pools. Due to the specific capabilities of the neutrons to move in air, the signal detected by the sensor installed above-ground is sensitive to an area of hundreds of meters providing a new perspective for proximal land-surface observations. The measurements are generally performed based on moderated proportional counters filled with Helium-3 or Boron and the moderation is created by adding shielding material (mostly polyethylene) around the counter.

The signal is affected by the temporal variability of the incoming neutron fluxes. At first, the variability of neutron fluxes is due to solar activities. The neutrons are further attenuated by the mass of the air and air humidity.

Specific corrections have been proposed to account for these effects. Air pressure and humidity corrections rely on local measurements that could be easily collected. Incoming correction due to solar cosmic-ray fluctuation is based on a worldwide network monitoring station (NMDB). This network provides online access to their data in real-time. However, this approach showed some limitations in region where incoming fluxes could be not representative of local conditions introducing errors that could be relevant for the estimation of the targeted variable. In addition, it requires the need of post-processing of the data resulting in some difficulties to provide, e.g., soil moisture observations in real-time.

In the present contribution, we show the results of tests conducted on an alternative commercial sensor based on scintillators. The new probe has the capability to identify different neutron energies ranges and gamma-rays providing new opportunities for hydrological observations at different spatial scales. In addition, the probe is sensitive to high energy particles that can be used for correcting the neutron signal by the variations of primary cosmic-ray flux. We present results from the comparison of the new probe with standard proportional counters and neutron monitor database in a long-term outdoor case study. We show how the use of local high energy particles is a practical alternative to account atmospheric corrections and overcome the limitation of using data from NMDB.
From Pasture and Cropland to Nut Orchards: Modelling the Dynamics of Carbon Sequestration by Agroforestry Systems in the Temperate Climate Zone.
Authors: Roest Erik , Lansu Angelique , Baltissen Ton , Dekker Stefan C.
Published: March 2020

Planting trees is suggested as a cheap measure to capture CO2, but might conflict with agricultural land use. Changing pasture and cropland into agroforestry systems like nut orchards might increase carbon (C) sequestration, without encroaching on agricultural land use. C-sequestration can act as a climate engineering measure to mitigate increasing CO2 emissions to the atmosphere. The general discourse is that agroforestry systems can sequester more carbon than cropland or pastures. Data on the impact of land use change from agriculture to agroforestry systems like nut orchards in the temperate climate zone are scarce.

In this study we analysed C-sequestration dynamics in above and below soil stocks and fluxes, from the perspective of global climate mitigation. Field measurements and lab results on chronosequences from pasture and cropland to stands of Corylus and Juglans trees have been combined with modelling future pathways at the level of parcels. The object of study was a temperate nut orchard located on sandy soils in the Netherlands (Province Gelderland).

Data on C stocks and fluxes have been collected in four methods: (1) field sampling analysed in a laboratory, (2) field survey, (3) collecting historic agricultural management data by interviewing and document analysis, and (4) analysing data by literature review. Focus was on C-stock data analysis and additional analysis of the C-budget change over years (chronosequence).

Results show different patterns (all data related to sequestration in reference plots):

C-sequestration in soil organic carbon (based on field samples, 0-60cm depth) ranges from -0.1 to 2.2 Mg C ha-1yr-1.

C-sequestration in Corylus trees (based on field data and allometric equations) ranges from 0.5 to 1.2 Mg C ha-1yr-1.

C-sequestration in Juglans trees (based on field data and allometric equations) ranges from 0.3 to 0.7 Mg C ha-1yr-1.

C-sequestration in below ground biomass (based on allometric equations) ranges from 0.06 to 0.4 Mg C ha-1yr-1.

The parameterized allometric equations show a large increase in C-sequestration, ranging from 0.9 to 3.5 Mg ha-1yr-1. Compared to grassland and cropland estimates this is 10 times higher, meaning a potential useful contribution to the mitigation of CO2 emissions. Further we observed an increase in quality of soil organic carbon, due to a shift to higher C/OM and C/N levels, lower annual OM breakdown and larger amounts of observed earthworms.

 
Identifying Heritage Sites using Data Fusion on Location of Spiritual Sites and Geodata: A Case Study of Archeological Investigations in Brunei Darussalam
Authors: Becek Kazimierz , Ibrahim Khairunisa , Krupa-Kurzynowska Joanna
Published: March 2020

Human civilization and culture on Borneo had generally developed in strong spatial relationship with rivers. Borneo rivers, almost constantly filled in by heavy tropical rains, were ideal topographic features for humans to build their dwellings over and along their banks. Also, as the rivers were full of fish and the banks rich in sago palms and animals, they provided a diversified livelihood for the population limiting agricultural activities. The rivers were also almost exclusive means of transportation to support the trade. These spatial constraints successfully harnessed by the Borneo population ensured the size of the human footprint remained small, thus maintaining the pristine forests with only a very limited space taken up by human settlements. Construction materials for houses were exclusively forest products, which tend to decay quickly because of the high humidity and air temperature. The only durable remains of abandoned human settlements are pottery, clay deposits, some stone and metal objects brought from the North, e.g., China. Therefore, the quest to uncover the cultural heritage of Brunei Darussalam is an extremely challenging one. In this contribution, we report on an attempt to use remote sensing and geoinformation to identify the most likely locations of long-abandoned human settlements. An initial data set is the location of cemeteries and mosques. Besides, topographic data, including LiDAR data, the location of rivers and ponds, abandoned rice fields, landslides, secondary forest plots, historical records, are utilized. Developed maps from this geodata will support possible subsequent archaeological investigations by helping to identify the location of sites of interests. The outcomes of this project may be of interest not only to government departments in charge of the historical and cultural heritage of Brunei Darussalam but also to ecologists documenting the interactions between human civilization and nature.
Reduction in lumen area increases the amount of δ18O exchange with source water during cellulose synthesis
Authors: Hu Jia , Szejner Paul , Clute Timothy , Anderson Erik , Evans Michael
Published: March 2020

Fine-scale sampling of secondary growth, isotopic composition and wood anatomical features has enabled the study of intra-seasonal tree growth dynamics in response to environmental and ecophysiological processes, and this fine-scale sampling approach has led to a re-examination of our fundamental understanding of how environmental factors are recorded in δ18O of cellulose (δ18Ocell). High resolution xylem anatomical analyses, such as wood density, lumen area (LA), cell wall thickness (CWT), and blue intensity have also been used to understand tree response to climate. However, linking wood anatomical traits with their isotopic signature has not yet been explored, but can provide new insights on the interpretation of the δ18Ocell through time. In this study, we test the response of wood anatomical features in Pinus ponderosa and Pseudotsuga menziesii, including cell-wall thickness (CWT) and lumen area (LA), along with the oxygen isotopic composition of α-cellulose (δ18Ocell) to shifts in relative humidity (RH) in two treatments: one from high to low RH and the second one from Low to high RH. We observed a significant decrease in LA and a small increase in CWT within the experimental growing season in both RH treatments. The measured δ18Ocell along the tree ring was also responsive to RH variations in both treatments. However, estimated δ18Ocell did not agree with measured δ18Ocell when the proportion of exchangeable oxygen during cellulose synthesis (Pex) was kept constant. We found that modeled δ18Ocell agreed with measured δ18Ocell only when Pex increased through the ring formation; we also found that Pex linearly decreased with an increase in standardized LA. Based on this varying Pex within an annual ring, we propose a targeted sampling strategy for different hydroclimate signals: earlier season cellulose (larger LA) is a better recorder of relative humidity while late season cellulose (smaller LA) is a better recorder of source water.
Ground-based and satellite measurements of the SO2 plume from the eruption of Raikoke volcano in June 2019
Authors: Fioletov Vitali , Sioris Chris , Zhao Xiaoyi , Griffin Debora , McLinden Chris , Brohart Michael , Lee Sum Chi , Carn Simon , Bognar Kristof , Strong Kimberly , Mao Jingqiu , Theys Nicolas , Loyola Diego , Hedelt Pascal , Krotkov Nickolay , Li Can , Boone Chris
Published: March 2020

The eruption of the Raikoke volcano (Kuril Islands) on June 21-22, 2019, created a large plume of sulfur dioxide (SO2) that reached the upper troposphere and lower stratosphere. The plume persisted in the atmosphere over the middle and high latitudes of the Western Hemisphere for more than a month creating a rare validation opportunity with multiple collocated measurements from ground and space both revealing enhanced SO2 vertical column densities (VCDs). Moreover, since the plume was often located over high latitudes, multiple orbits per day from the polar orbiting satellites could be utilized. Pandora sunphotometer measurements at Edmonton and Eureka, Canada, and at Fairbanks, Alaska, and Brewer spectrophotometer measurements at seven Canadian sites (Saturna, Edmonton, Churchill, Resolute, Eureka, and Alert) reported SO2 values up to 15 Dobson Units (DU, where 1 DU = 2.69 × 1016 molecules/cm²). These measurements were compared with satellite SO2 VCDs obtained by the Sentinel 5p TROPOspheric Monitoring Instrument (TROPOMI), AURA Ozone Monitoring Instrument (OMI), and Suomi NPP Ozone Mapping Profiling Suite (OMPS). Back-trajectory Lagrangian model analysis and satellite SO2 profile measurements by the Atmospheric Chemistry Experiment mission Fourier transform spectrometer (ACE/FTS) on board the Canadian satellite SCISAT demonstrated that the volcanic plume was located at 8-25 km. In general, ground-based and satellite measurements show a very good agreement. However, the exact ground-based and satellite viewing geometry should be considered when such measurements are taken near the edge of the plume.
The seesaw response of the Intertropical and South Pacific convergence zones to hemispherically asymmetric thermal forcing
Authors: Zhao Bowen , Fedorov Alexey
Published: March 2020

Arguments based on atmospheric energetics and aqua-planet model simulations link the latitudinal position of the Intertropical Convergence Zone (ITCZ) to atmospheric cross-equatorial energy transport –- a greater southward transport corresponds to a more northerly position of the ITCZ. This idea is often invoked to explain an interhemispheric dipole pattern of precipitation anomalies in paleoclimates. In contrast, here we demonstrate that in the tropical Pacific the response of the fully coupled ocean-atmosphere system to a hemispherically asymmetric thermal  forcing, modulating this energy transport, involves an interplay between the ITCZ and its counterpart in the South Pacific - the Southern Pacific Convergence Zone (SPCZ). This interplay leads to interhemispheric seesaw changes in tropical precipitation, such that the latitudinal position of each rain band remains largely fixed, but their intensities follow a robust inverse relationship. The seesaw behavior is also evident in the past and future coupled climate simulations of the Climate Model Intercomparison Project Phase 5 (CMIP5). We also show that the tropical Pacific precipitation response to thermal forcing is qualitatively different between the aqua-planet (without ocean heat transport), slab-ocean (with climatological ocean heat transport represented by a ``Q-flux'') and fully-coupled model configurations. Specifically, the induced changes in the ITCZ latitudinal position successively decrease, while the seesaw precipitation intensity response becomes more prominent, from the aqua-planet to the slab-ocean to the fully-coupled configuration. Thus, the ITCZ/SPCZ seesaw can explain the paleoclimate precipitation dipole pattern without invoking a too strong climate forcing and is relevant to future projections of tropical precipitation.
The decadal climate prediction skill with focus on the North Atlantic region
Authors: Yang Shuting , Christiansen Bo
Published: March 2020

The skill of the decadal climate prediction is analyzed based on recent ensemble experiments from the CMIP5 and CMIP6 decadal climate prediction projects (DCPP) and the Community Earth System Model (CESM) Large Ensemble (LENS) Project. The experiments are initialized every year at November 1 for the period of 1960-2005 in the CMIP5 DCPP experiments and 1960-2016 for the CMIP6 DCPP models as well as the CESM LENS decadal prediction. The CMIP5/6 ensemble has 10 members for each model and the CESM ensemble has 40 members. For the considered models un-initialized (historical) ensembles with the same forcings exist. The advantage of initialization is analyzed by comparing these two sets of experiments.

We find that the models agree that for lead-times between 4-10 years little effect of initialization is found except in the North Atlantic sub-polar gyre region (NASPG). This well-known result is found for all the models and is robust to temporal and spatial smoothing. In the sub-polar gyre region the ensemble mean of the forecast explains 30-40 % more of the observed variance than the ensemble mean of the historical non-initialized experiments even for lead-times of 10 years.

However, the skill in the NASPG seems to a large degree to be related to the shift towards warmer temperatures around 1996. Weak or no skill is found when the sub-periods before and after 1996 are considered. We further analyze the characteristics of other climate indicators than surface temperature as well as the NAO to understand the cause and implication of the prediction skill.
A pseudo-single domain theory of paleomagnetic recording
Authors: Fabian Karl , de Groot Lennart V.
Published: March 2020

The common theory of paleomagnetic recording is based on the acquisition of thermoremanent magnetization in  single-domain (SD) particles (Neel, 1955). The physical consequences of this theory  agree  well enough  with observations as to be of utmost use in understanding and assessing the quality of paleomagnetic data in almost all practical applications in paleomagnetism. This is to a large extent due to the statistical nature of the interpretations based on SD theory, which apparently is sufficiently robust to make up for minor descrepancies between the real remanence carriers and their physical description on which the statistical interpretation is founded. Exceptions to this rule are becoming more important as increasingly sophisticated technical methods for paleomagnetic measurements are developed and used, that involve fewer and fewer individual magnetic particles to contribute to the measured signal. Examples are the determination of paleointensity from individual mineral grains, and the development of scanning magnetometers that average over relatively small numbers of magnetic grains in a sample. The statistical uncertainties of paleomagnetic quantities resulting from using small sample sizes have been studied for SD particle ensembles for example by Berndt et al. (2016).  First experimental data indicate that in case of PSD particles the statistical sample size required to  reconstruct paleomagnetic field direction may be smaller than for SD particles. Here, a theoretical study is presented that describes the micromagnetic background of this hypothesis and allows to test  it for a simplified mathematical model of TRM acquisition in PSD particles.
Soil Degradation in Argan Woodlands, South Morocco
Authors: Kirchhoff Mario , Engelmann Lars , Zimmermann Lutz Leroy , Marzolff Irene , Seeger Manuel , Aït Hssaine Ali , Ries Johannes B.
Published: March 2020

The argan tree (Argania spinosa) populations, endemic to South Morocco, have been highly degraded. Although the argan tree is the source of the valuable argan oil and is protected by law, overbrowsing and -grazing as well as the intensification and expansion of agricultural land lead to tree and soil degradation. Young stands cannot establish themselves; undergrowth is scarce due to the semiarid/arid climate and thus, goats, sheep and dromedaries continually browse the trees. Canopy-covered areas decrease and are degraded while areas without vegetation cover between the argan trees increase.

On 30 test sites, 60 soil samples of tree and intertree areas were studied on their soil physical and chemical properties. 36 rainfall simulations and 60 single-ring infiltration measurements were conducted to measure potential differences between tree/intertree areas in their runoff/erosion and infiltration properties. Significant differences using a t-test were found for the studied parameters saturated hydraulic conductivity, pH, electric conductivity, percolation stability, total C-content, total N-content, K-content, Na-content and Mg-content. Surface runoff and soil erosion were not statistically significant, but showed similar trends due to the higher complexity of runoff formation. The soil covered by argan trees generally showed less signs of degradation than intertree areas. With ever-expanding intertree areas due to the lack of rejuvenation of argan trees a further degradation of the soil can be assumed.
Multidisciplinary analysis at Lake Moo: Changes in high intensity precipitation on the Northern Apennines (Italy) over the last 9000 years
Authors: Segadelli Stefano , Grazzini Federico , Aguzzi Margherita , Chelli Alessandro , Rossi Veronica , De Nardo Maria Teresa , Francese Roberto , Marvelli Silvia , Marchesini Marco , Nanni Sandro
Published: March 2020

The Lake Moo plain has a surface area about 0.15Km2. It is located near the boundary between Emilia-Romagna and Liguria regions, at an altitude of 1130m a.s.l. (northern Apennines, Italy). This site is strategic to the dominant atmospheric currents, very prone to high intensity precipitation events (HIP) and related high-density flood. Indeed, Lake Moo area has been partially covered by a flood deposit released by a record-breaking rainfall intensity in September 2015. The intensity and wide spatial scale of those phenomena has leads us to investigate their frequency in the past, beyond the instrumental time. The lacustrine succession (ca. 13 m-thick) was studied through the extraction of one core and framed within sedimentary facies analysis approach. The paleoenvironmental interpretation of the succession was achieved combining sedimentological, pollen and pedological data and radiocarbon dating. Thirteen different facies types have been identified and the core succession is was subdivided into five informal units. The different coarse-grained layers interbedded with organic-rich silty clays and peaty layers have been interpreted as the extreme flood deposits triggered by high-intensity convective rainfall events in the catchment area that flow into the Lake Moo plain.

These coarse-grained deposits were grouped according to the genetic approach and therefore based on facies tract concept. The goal of this study is how the facies tract approach may represent a novel method that can be used to improve our understanding of flood reconstruction dynamics and may be applied to other similar deposits. We interpret the local lacustrine succession is like to the infill of a structural depression produced by gravitational block sliding that was induced by post-glacial fluvial incision.

Finally, the observed depositional cycles were put in relation with other specific paleoclimatic proxies available in literature for the area.
Tracing plant water fluxes in ecosystems by stable isotopes along the soil-plant and plant-atmosphere interfaces
Authors: Werner Christiane
Published: March 2020

Terrestrial vegetation is a main driver of ecosystem water fluxes, as plants mediate the water fluxes within the soil-vegetation-atmosphere continuum. Stable isotopologues of water are efficient tracer to follow the water transfer in soils, uptake by plants, transport in stems and release into the atmosphere through stomata. The development of in-situ methods coupled to isotope spectroscopy does now enable real-time in-situ water vapour isotopologue measurements revealing high spatial and temporal dynamics, such as adaptations in root water uptake depths (within hours to days) or the impact of transpirational fluxes on atmospheric moisture.

Examples will be given how isotopes can be used to inform the complex interplay between plant ecophysiological adaptations and hydrological processes. For example, root water uptake is not solely driven by soil water availability but has to be understood in the context of species-specific regulation of active zones in their rooting system determining the conductivity between soil and roots regulating uptake depths. The latter has also to be evaluated in context of the nutrient demand and the spatial nutrient availability. Similarly, plant water transport and losses are a fined tuned interplay between species-specific structural and functional adaptations and atmospheric processes.

Finally, first data of a large-scale ecosystem labelling experiment at the Biosphere 2 tropical rainforest of the B2 Wald, Atmosphere, and Live Dynamics (B2WALD) will be presented.
Source mechanisms of seismic events during the 2018 eruption of Sierra Negra Volcano (Galapagos) determined by using polarization properties of complete (near-field and far-field) body waves
Authors: Nooshiri Nima , Lokmer Ivan , Bean Chris , Bell Andrew , Möllhoff Martin , Ruiz Mario
Published: March 2020

Sierra Negra is a basaltic shield volcano in the Galapagos Archipelago (Ecuador) and is the largest of the Galapagos volcanoes. The 2018 eruption was a complex event that included eruptive fissures opening on the northern rim and north-western flank. In this study, we report observations of seismic signals recorded on a temporary dense local network consisting of 14 seismometers and nearby permanent seismic stations, and analyze this data set to retrieve the source mechanisms of moderate pre- and co-eruptive seismic events (body-wave magnitude range of M3.5-5.3). Because of the shallow depths of the seismic events (<2 km) and short source-receiver distances (~1.5-10 km), that are comparable to or shorter than the wavelengths of radiated waves, the effect of near- and intermediate-field terms on dynamic displacements can be significant and hence the far-field assumption may not be well-suited for determining fault-plane solutions. Therefore, we pay special attention on the polarization properties of seismic waves excited at the near-field and intermediate-field ranges, and model and analyze complete displacement wave-fields to determine seismic sources. The source mechanism solutions are also interpreted in light of the volcanic unrest leading to the 2018 eruption, GPS observations, and reported regional centroid moment tensors.
Eocene - Oligocene paleobathymetry of the Atlantic - Arctic Oceanic Gateways: Influence on ocean circulation and climate
Authors: Nummelin Aleksi , Straume Eivind O. , Gaina Carmen , LaCasce Joseph Henry , Nisancioglu Kerim H.
Published: March 2020

The Eocene-Oligocene boundary (~ 34 Ma) marks a turning point in the transition from a warm greenhouse climate to a cold icehouse climate in the Cenozoic time (66 – 0 Ma). Around this boundary, geological evidence shows the first signs of ice sheets on Antarctica, and evidence of ice-rafted debris offshore East Greenland. Topographic changes, especially the opening and closing of strategic oceanic gateways, have been proposed as triggers for this climate cooling. 

We have developed a new global paleobathymetry/topography model for the Eocene-Oligocene boundary with focus on the Northern hemisphere oceanic gateways and implemented our reconstruction in the Norwegian Earth System Model (NorESM-F). Our new topography model shows that changes in these gateways also occurred around this time, especially in the NE Atlantic Ocean and the Tethys Seaway. To test the importance of these gateways and their combined effects we create a set of model simulations by changing the paleobathymetric configurations of the most important oceanic gateways (i.e. the Greenland – Scotland Ridge, Fram Strait, Southen Ocean gateways and the Tethys Seaway). All the scenarios are detailed realistic reconstructions within the error of our paleobathymetry/topography model. The model shows that the depth of the Greenland-Scotland ridge controls the freshwater input to the North Atlantic and opening the gateway leads to large Northern hemispheric cooling as the freshwater reduces ocean convection and the Atlantic overturning circulation slows down. On the other hand, opening the Southern Ocean gateways facilitates the flow of the Antarctic Circumpolar Current and leads to expected cooling in Antarctica. Based on our model results we suggest that bathymetric changes around the Eocene - Oligocene boundary were important in initiating the cooling which was then enhanced by feedbacks in the Earth System.​
Optimality in landscape channelization and analogy with turbulence
Authors: Hooshyar Milad , Bonetti Sara , Singh Arvind , Foufoula-Georgiou Efi , Porporato Amilcare
Published: March 2020

The channelization cascade observed in terrestrial landscapes describes the progressive formation of large channels from smaller ones starting from diffusion-dominated hillslopes. This behavior is reminiscent of other non-equilibrium complex systems, particularly fluids turbulence, where larger vortices break down into smaller ones until viscous dissipation dominates. Based on this analogy, we show that topographic surfaces emerging between parallel zero-elevation boundaries present a logarithmic scaling in the mean-elevation profile, which resembles the well-known logarithmic velocity profile in wall-bounded turbulence. Within this region of elevation fluctuation, the power spectrum exhibits a power-law decay resembling the Kolmogorov -5/3 scaling of turbulence. We also demonstrate that similar scaling behaviors emerge in surfaces from a laboratory experiment, natural basins, and constructed following optimality principles. In general, we show that the steady-state solutions of the governing equations of landscape evolution are the stationary surfaces of a functional defined as the average domain elevation. Depending on the exponent of the specific drainage area in the erosion term (m), the steady-state surfaces are local minimum (m<1) or maximum (m>1) of the average domain elevation.
Measurement and analysis of extreme storm waves off the Irish coast
Authors: Herterich James , Fedele Francesco , Tayfun Aziz , Dias Frederic
Published: March 2020

We present a statistical analysis of nearshore waves observed during two major north-east Atlantic storms in 2015 and 2017. Surface elevations were measured with a 5-beam acoustic Doppler current profiler (ADCP) at relatively shallow waters off the west coast of Ireland. To compensate for the significant variability of both sea states in time, we consider a novel approach for analyzing the non-stationary surface-elevation series and compare the distributions of crest and wave heights observed with theoretical predictions based on the Forristall, Tayfun and Boccotti models. In particular, the latter two models have been largely applied to and validated for deep-water waves. We show here that they also describe well the characteristics of waves observed in relatively shallow waters. The largest nearshore waves observed during the two storms do not exceed the rogue thresholds as the Draupner, Andrea, Killard or El Faro rogue waves do in intermediate or deep-water depths. Wave breaking limits wave growth and impedes the occurrence of rogue waves. Nevertheless, our analysis reveals that modulational instabilities are ineffective, third-order resonances negligible and the largest waves observed here have characteristics quite similar to those displayed by rogue waves for which second order bound nonlinearities are the principal factor that enhances the linear dispersive focusing of extreme waves.

Fedele, F., Herterich, J., Tayfun, A., & Dias, F. (2019). Large nearshore storm waves off the Irish coast. Scientific reports, 9(1), 1-19.
Investigating the volcanic impacts on Tropical South Atlantic modes of variability for the Historical period using the IPSL-CM6-LR Large Ensemble and INPE-BESM
Authors: Lobo Lopes Eduardo , Elazari Klein Coaracy Wainer Ilana , Khodri Myriam
Published: March 2020

In this study we investigate the the South Atlantic Ocean response to large tropical volcanic eruptions for the historial periods. In particular, we analyse the changes in the coupling of the ocean and the atmosphere over that ocean basin triggered by changes in the amount of incoming shortwave radiation.

The analysis consists of averaging the response of the five biggest eruptions in the last 200 years, namely, Krakatoa (1883), Santa Maria (1902), Agung (1963), El Chichón (1982) and Pinatubo (1991), represented by the IPSL-CMP6-LR Large Ensemble, from the Institut Pierre Simon Laplace, and the BESM-CMIP6, from INPE-CPTEC. We perform the same analysis on reanalysis products as well, such as the HadISST and NOAA's ERSSTv5.

In order to capture the interannual change in the climate variability, we use two climate indices that assess the coupling of ocean and atmosphere over this timescale, namely, the Atlantic Meridional Mode (AMM) and the South Atlantic Subtropical Dipole (SASD). We compute their time series from the model output and calculate their regression to the SST and precipitation fields.

Such analysis should yield more insights on how the interaction between the ocean and the atmosphere responds to external forcings, providing a better understanding of the processes that control the climate variability over the South Atlantic Ocean basin.
Emergency shelter selection in the context of seismic risk. Case study – Bucharest, Romania
Authors: Popovici Diana , Armaș Iuliana , Toma-Dănilă Dragoș , Gavriș Alexandru
Published: March 2020

Big cities are prone to suffer important losses, both economic and human, in case of a risk occurrence. Bucharest is the most vulnerable European capital to earthquakes due to its exposure, being located about 130 km from the main seismic region of the country – Vrancea Region, and also due to its high physical and social vulnerability.

Based on the past experiences and on the present development of the city, there is an urge to find and to develop measures and policies for seismic risk mitigation. The first step in this direction, which is also the aim of the present work, is to assess the current situation regarding the vulnerability of the city and to understand the dimension of the losses throughout the city in case of a major earthquake event.

In this study we discuss the best locations to deploy shelters which can provide first-aid and temporary residence for those who lost their homes after an earthquake event. Our research is based on estimating the losses at a detailed scale and by knowing the limitations of the infrastructure (including emergency hospitals and roads) and of the public services (like the firefighters, ambulances, police, medical care etc.).

Social, economic and housing quality criteria were integrated in a multicriteria analysis in order to assess the most vulnerability hotspots at city level and to estimate losses. The results showed the presence of two extended areas, situated in the south-west and the western part of the city, with high vulnerability scores and high potential losses. These two areas were introduced into a new multicriteria analysis for finding suitable locations that can be used as indoor and outdoor shelters.

Our study is a step forward to increase the preparedness of the population, that will know where to go in case of need. It will also help the authorities that will better allocate their resources and overall mitigate the seismic risk.
Mesospheric water vapor and D/H ratio at the Venus terminator from SOIR/VEx
Authors: Mahieux Arnaud , Vandaele Ann Carine , Chamberlain Sarah , Wilquet Valérie , Robert Séverine , Piccialli Arianna , Thomas Ian , Trompet Loic
Published: March 2020

The Solar Occultation in the InfraRed (SOIR) instrument onboard Venus Express sounded the Venus mesosphere and lower thermosphere at the terminator using solar occultation technique between April 2006 and December 2014.

We report on the water vapor vertical distribution above the clouds and geo-temporal variations, observed during the full Venus Express mission. Water vapor profiles are sampled between 80 and 120 km, and calculations of the water vapor volume mixing ratio agrees with those from previous studies. Short term variations over several Earth days dominate the data set, with densities varying by up to a factor 19 over a 24 hr period. Similarly to what was found for other trace gases detected with the SOIR instrument, such as HCl, HF and SO2, no significant spatial or long term trends are observed.

287 water vapor vertical profiles obtained at the Venus terminator between 80 km and 120 km from August 2006 and September 2014 were analyzed for temporal and spatial abundance variations. Standard deviations are significantly smaller than the full range of volume mixing ratio values at all altitudes indicating that the variations are real.

The decrease in volume mixing ratio abundance below 100 km appears to be a common feature of most water vapor volume mixing ratio profiles and agrees with the decrease in water vapor reported in previous studies. Based on a very limited number of spectra, the variability of the water vapor VMR was found to be higher in the lower than in the upper mesosphere of Venus; this is in agreement with our observations as the standard deviation of the SOIR mean profile is the smallest at 100 km and increases with decreasing altitude.

No significant spatial variations or long term temporal variations are observed in the present data set in which short term variability masks all other possible trends. Our observations agree that short term (between 1 and 10 Earth days) variability is dominant.

We also report on simultaneous observations of the water first isotopologue HDO made by SOIR, which occurred 194 times during the whole VEx mission. Similarly to water vapor, we observe a large variation of HDO with time and space, without any clear time of spatial dependency.

We report on the ratio of the simultaneously measured HDO and H2O profiles, that show a constant ratio of 0.1 ± 0.1 below 100 km, and increase exponentially at higher altitude to reach a value of 1 ± 0.4 at 120 km of altitude. The results are in agreement with previous works below 100 km.
Towards a better understanding of past biotic drivers of river and floodplain geomorphology
Authors: Larsen Annegret , Reimann Tony , Sperisen Christoph , Robin Vincent , Lane Stuart N
Published: March 2020

Geomorphology has long considered the role of abiotic factors in geomorphic processes, including tectonics, geology, climate and relief, as well as humans impact upon them. Biotic factors however, including not only plants but also bacteria and protists, biofilms, fungi, insects, invertebrates, and animals are increasingly recognized as governing geomorphic processes on many spatial and temporal scales. We argue that if fauna are important as geological agents, then understanding the complex response of geomorphic systems to fauna is necessary to understand the past, present and future of the fluvial environment. It is not surprising that studies of the Late Quaternary evolution of fluvial morphodynamics have largely focused upon changes in the sedimentary soil-sediment sequences that result from climate change; (ii) vegetation change; and/or (iii) human impacts. Reconstruction of vegetation and climate from pollen and other records facilitates these analyses. But if animals are shown to be an important influence on geomorphic processes today, then it is quite possible that they were also important historically. For example, conclusive interpretation of Holocene river changes may be limited because of an incomplete or partial account of the presence and/or absence of data on the role of ecosystem engineers in modifying the riparian and aquatic ecosystems, including hydro-geomorphic processes. DNA found within historical deposits may be used to constrain the role of past ecosystem engineers. Analysis of ancient environmental DNA up to date includes palaeo-environmental DNA from sedimentary deposits (sedaDNA) from disseminated genetic material found within sedimentary archives, including paleo-dietary ancient DNA. Here, we use an analogue study investigating the present hydro-geomorphic and biogeochemical changes that the ecosystem engineer beaver (Castor fiber) creates at four sites in central Europe to better understand and quantify the effects of beaver ecosystem engineering on a seasonal to decadal scale. We utilize these results to interpret the chrono-stratigraphy of two Holocene beaver sites, including macro-fossil and sedaDNA sampling, and test for the first time if sedaDNA can support the investigation of beaver-induced palao-environmental conditions in river floodplains. We find that sedaDNA data and other palaeo-botanical proxies complement each other showing wider diversity of species than if the methods are used separately. However, care must be taken with regards of experimental setup, and further investigation into the effects of transport processes and/or quantitative representativeness is needed.
Changes in soil warming effects on microbial C, N and P cycling across seasons in a temperate calcareous mixed forest
Authors: Tian Ye , Urbina Malo Carolina , Shi Chupei , Zhang Shasha , Heitger Marilena , Kwatcho Kengdo Steve , Borken Werner , Heinzle Jakob , Schindlbacher Andreas , Wanek Wolfgang
Published: March 2020

Global warming may accelerate soil carbon (C) and nutrient cycling as higher temperatures accelerate soil microbial and enzymatic activities. However, this enhanced soil C cycling can diminish with time due to the depletion of labile soil C or due to thermal acclimation of soil microbes, while the increased N cycling may be dampened over time in N-rich soils. Moreover, soil climate as well as the quality and quantity of plant inputs change between seasons, which could influence the C: nitrogen (N): phosphorus (P) stoichiometry of resources available for microbes and thereby alter the warming effect on microbial activities and nutrient cycling between seasons. Such seasonal changes caused inconsistent warming effects on extracellular enzyme activities and on soil respiration in some experiments, with warming effects turning from positive to negative between seasons, yet the underlying controls of these adverse effects are far from being well understood. In this study, we therefore aimed to investigate soil warming and seasonal effects on soil C, N, and P pools and processes in a temperate calcareous mixed forest. We collected soil samples in spring, summer and fall (May, August, and October 2019) from a long-term (>15 yrs) soil warming experiment in Achenkirch, Northern Limestone Alps, Austria (47°34’ 50’’ N; 11°38’ 21’’ E; 910 m a.s.l.). The samples were incubated at the corresponding in-situ temperatures in the laboratory. Microbial growth, respiration and C use efficiency were determined by following 18O-H2O incorporation in DNA and by gas analysis. 15N pool dilution assays were applied to quantify gross rates of protein depolymerization, N mineralization, and nitrification, whilst gross rates of soil inorganic P mobilization were measured by a 33P pool dilution assay. Moreover, we measured the potential soil enzyme activities of four hydrolases and two oxidases, and determined contents of labile (extractable) and microbial biomass C, N, and P. This study will thereby provide a comprehensive insight into how soil warming influences soil microbial C, N, and P cycling in a temperate calcareous mixed forest as well as into their energetic, stoichiometric and soil microclimatic constraints. The long-term nature of this soil warming experiment will therefore allow predictions of the future biogeochemical behavior of calcareous forest soils, and deduce potential feed-backs on forest productivity, atmospheric composition and climate change.
Manifestations and mechanisms of the Karakoram glacier Anomaly
Authors: Farinotti Daniel , Immerzeel Walter W. , de Kok Remco J. , Quincey Duncan J. , Dehecq Amaury
Published: March 2020

Due to ongoing climatic change, glacier mass loss and retreat are observed all over the globe. The changes are beyond historic precedence, affect ice masses from the polar ice sheets to the highest mountain glaciers, and cause concerns ranging from rising sea levels to water scarcity. The impacts on water resources are particularly important when glaciers supply water to downstream populations, as is the case in High Mountain Asia (HMA).

Amongst this general picture of glacier wastage, one region stands out because of its anomalous behavior: The Karakoram. Located in the border regions of China, India, and Pakistan, the Karakoram and the nearby Western Kun Lun have been identified as a region in which glaciers were in balance or even slightly gaining mass during recent decades. Geodetic assessments show negligible to slightly positive volume changes, analyses of surface ice flow velocities show steady to increasing ice flow, and glacier inventories reveal a concentration of surge-type glaciers that is unique to HMA.

In this contribution, we review the present-day understanding of what has been known as the “Karakoram Anomaly” since the early 2000s. We show that evidence is accumulating for the Anomaly extending into the Western Kun Lun and Pamirs, and for being due to a combination of factors, including (i) an increase in westerlies-dominated winter snowfalls, (ii) an increase in diurnal temperature ranges possibly related to large-scale deforestation, (iii) a summer cooling linked to the weakening of the monsoon, (iv) an increase in atmospheric moisture likely due to an expansion of  regional irrigation, (v) an increase in summer accumulation resulting from both the summer cooling and the increased moisture, and (vi) reduced ablation due to a moisture-related increase in cloudiness and decrease in incoming shortwave radiation.

Our work assesses the relative level of confidence of the individual mechanisms, and highlights potential pathways that may further improve our understanding.
Effects of nitrogen fertilization on yield and nitrogen-use efficiency of durum wheat in Tunisia: a meta-analysis
Authors: Souissi Amir , Bahri Haithem , Cheikh M’hamed Hatem , Annabi Mohamed
Published: March 2020

Durum wheat (Triticum durum Desf.) is a crucial food crop and has occupied important areas in Tunisia. However, its production remains low and unstable even though the effort of intensification of this crop has been undertaken for many decades. Likewise, Nitrogen (N) is a major limiting input factor for the crop production. In this vein, the main objective of this meta-analysis is to quantify N-use efficiency of N-fertilizer (NUE) of durum wheat in Tunisia from published studies according to the type of crop management and bioclimatic zone. Nine hundred thirty-six observations (including grain yield and NUE as dependent variables) were extracted from 51 published studies, corresponding to trials conducted in rain-fed or irrigated, and conducted in conventional system or no-tillage. The results demonstrated that yields obtained within the experimental studies were below the cultivar potential yield, even at irrigated conditions. The grain yields obtained in no-tillage trials were lower (-26%) than those in conventional tillage ones. On the other hand, N-use efficiency was small and varied between 36 and 58 kg kg-1 N depending on the bioclimatic zone. Overall, the effect of irrigation on N-use efficiency was significantly positive (+16.4 kg kg-1 N; p <0.05) under conventional systems. Whereas NUE response to no-tillage was significantly negative (-12.1 kg kg-1 N; p <0.001) under rain-fed conditions. This latter is due mainly to the limitation of conservation agriculture (CA) in Tunisia to only no tillage practice and the negligence of the two other principles of CA namely crop rotations/species diversity, and soil cover by crop residues (at least 30% of the soil surface covered by crop residue at crop sowing). Therefore, enhancing N-use efficiency of durum wheat in Tunisia is paramount to increase production and avoid nitric pollution issues. This feature involves a best management of N-fertilization via synchronizing the timing and quantity of the nitrogen supply with the plant needs, and via using decision-making tools such as chlorophyll meter SPAD and GreenSeeker®, in order to accomplish this synchronization. The nexus between water and nitrogen in the soil is essential since it has conditioned the nitrogen use by durum in Mediterranean conditions.