bluuebunny/crossref_metadata_2025 huggingface dataset:
Diurnal and seasonal variations in carbon ﬂuxes in bamboo forests during the growing season in Zhejiang province, China
Authors: Chen Liang
Published: March 2020

Bamboo forest is an important forest type in subtropical China and is characterized by fast growth and high carbon sequestration capacity. However, the dynamics of carbon ﬂuxes during the fast growing period of bamboo shoots and their correlation with environment factors are poorly understood. We measured carbon dioxide exchange and climate variables using open-path eddy covariance methods during the 2011 growing season in a Moso bam-boo forest (MB, Phyllostchys edulis) and a Lei bamboo. forest (LB, Phyllostachys violascens) in Zhejiang province, China. The bamboo forests were carbon sinks during the growing season. The minimum diurnal net ecosystem exchange (NEE) at MB and LB sites were - 0.64 and - 0.66 mg C m-2 s-1, respectively. The minimum monthly NEE, ecosystem respiration (RE), and gross ecosystem exchange (GEE) were - 99.3 ± 4.03, 76.2 ± 2.46, and - 191.5 ± 4.98 g C m-2 month-1, respectively, at MB site, compared with - 31.8 ± 3.44, 70.4 ± 1.41, and - 157.9 ± 4.86 g C m-2 month-1, respectively, at LB site. Maximum RE was 92.1 ± 1.32 g C m-2 month-1 at MB site and 151.0 ± 2.38 g C m-2 month-1 at LB site. Key control factors varied by month during the growing season, but across the whole growing season, NEE and GEE at both sites showed similar trends in sensitivities to photosynthetic active radiation and vapor pressure deﬁcit, and air temperature had the strongest correlation with RE at both sites. Carbon ﬂuxes at LB site were more sensitive to soil water content compared to those at MB site. Both on-year (years when many new shoots are produced) and off-year (years when none or few new shoots are produced) should be studied in bamboo forests to better understand their role in global carbon cycling.
On the dark side of the earth – How the Black Marble Alliance supports humanitarian activities with satellite-derived night-time light observations
Authors: Enenkel Markus , Román Miguel , Stokes Eleanor , Ranjay Shrestha , Patrick Vinck
Published: March 2020

Various satellite data are part of humanitarian decision-making workflows. The added value of daytime imagery is mostly obvious, contributing to damage and needs assessment or the monitoring of populations of concern among other applications. However, the development and practical humanitarian applications of night-time imagery are largely unexplored. New possibilities are emerging with the public release of NASA’s black marble dataset – a global nighttime lights product derived from the Visible Infrared Imaging Radiometer Suite (VIIRS) on-board the Suomi National Polar-orbiting Partnership (NPP) satellite. Emerging evidence demonstrates the added-value of the black marble dataset to assess disaster impact and displacement after cyclone Idai made landfall in Mozambique in March 2019. Similar data was used to monitor reconstruction efforts in Puerto Rico in the wake of hurricane Maria's landfall in 2017, uncovering socio-economic inequalities in electricity restoration efforts. This work is led by a unique collaboration between the Universities Space Research Association’s (USRA) Earth from Space Institute, NASA Goddard Space Flight Center, Harvard Humanitarian Initiative, the World Bank, logistics services companies, aid and development organizations. 
On the computation of phase inconsistencies of Sentinel-1 interferograms over snow-covered areas
Authors: Gritsevich Maria , Nico Giovanni , Conde Vasco , Mateus Pedro , Catalao Joao
Published: March 2020

We have recently investigated the use of SAR interferometry for the mapping of Snow Water Equivalent (SWE) temporal variations using Sentinel-1 data [1]. Maps of temporal changes of SWE, measured with a sub-centimetre accuracy and updated every six days have been obtained over a study area in Finland. This methodology relies on the shift in the interferometric phase caused by the refraction of the microwave signal penetrating the snow layer. In this work, we investigate phase inconsistencies [2] of a sets of three interferograms obtained from three Sentinel-1 images acquired along the same orbit at different acquisition times to study the snow melt. We find that while phase inconsistencies are not expected to be present in case of examining surfaces covered with frozen snow, the scattering mechanism of microwave in the snow layer during the melting phase affects both the interferometric phase and coherence.

 

This work was supported, in part, by the Academy of Finland project no. 325806.

 

References:

[1] V. Conde, G. Nico, P. Mateus, J. Catalão, A. Kontu, M. Gritsevich, On the estimation of temporal changes of snow water equivalent by spaceborne SAR interferometry: a new application for the Sentinel-1 mission, J. Hydrol. Hydromech., 67, 2019, 1, 93–100. DOI: 10.2478/johh-2018-0003

[2] F. De Zan, M. Zonno, P. López-Dekker, Phase inconsistencies and multiple scattering in SAR interferometry, IEEE Transactions on Geoscience and Remote Sensing, 53(12), 6608-6616, 2015
Constraining the model representation of the aerosol life cycle in relation to sources and sinks.
Authors: Kim Paul , Partridge Daniel , Haywood James
Published: March 2020

Global climate model (GCM) ensembles still produce a significant spread of estimates for the future of climate change which hinders our ability to influence policymakers. The range of these estimates can only partly be explained by structural differences and varying choice of parameterisation schemes between GCMs. GCM representation of cloud and aerosol processes, more specifically aerosol microphysical properties, remain a key source of uncertainty contributing to the wide spread of climate change estimates. The radiative effect of aerosol is directly linked to the microphysical properties and these are in turn controlled by aerosol source and sink processes during transport as well as meteorological conditions.

A Lagrangian, trajectory-based GCM evaluation framework, using spatially and temporally collocated aerosol diagnostics, has been applied to over a dozen GCMs via the AeroCom initiative. This framework is designed to isolate the source and sink processes that occur during the aerosol life cycle in order to improve the understanding of the impact of these processes on the simulated aerosol burden. Measurement station observations linked to reanalysis trajectories are then used to evaluate each GCM with respect to a quasi-observational standard to assess GCM skill. The AeroCom trajectory experiment specifies strict guidelines for modelling groups; all simulations have wind fields nudged to ERA-Interim reanalysis and all simulations use emissions from the same inventories. This ensures that the discrepancies between GCM parameterisations are emphasised and differences due to large scale transport patterns, emissions and other external factors are minimised.

Preliminary results from the AeroCom trajectory experiment will be presented and discussed, some of which are summarised now. A comparison of GCM aerosol particle number size distributions against observations made by measurement stations in different environments will be shown, highlighting the difficulties that GCMs have at reproducing observed aerosol concentrations across all size ranges in pristine environments. The impact of precipitation during transport on aerosol microphysical properties in each GCM will be shown and the implications this has on resulting aerosol forcing estimates will be discussed. Results demonstrating the trajectory collocation framework will highlight its ability to give more accurate estimates of the key aerosol sources in GCMs and the importance of these sources in influencing modelled aerosol-cloud effects. In summary, it will be shown that this analysis approach enables us to better understand the drivers behind inter-model and model-observation discrepancies.
Investigating the effects of the planetary rings on the azimuthal magnetic field at Saturn
Authors: Agiwal Omakshi , Dougherty Michele , Hunt Gregory , Cao Hao , Hsu Hsiang-Wen
Published: March 2020

Magnetic field observations from the 22 Cassini Grand Finale orbits have shown a mean lagging azimuthal magnetic field configuration on magnetic field lines mapping from Saturn to its main rings in the equatorial plane, with some orbit to orbit variability. A prominent feature is observed in the southern hemisphere on field lines connecting to the B-ring on 70% of the orbits, which is spatially consistent with the location of in-falling dust indicated by the Cosmic Dust Analyser instrument. In our work, we examine the possible connection between the in-falling charged dust and the B-ring magnetic field feature. We also use a simple steady-state model to couple the planetary ionosphere to a weakly conducting ring ionosphere over the main rings, where the model output shows an expected leading field configuration associated with the rings. The discrepancy between the simple theoretical model and the data indicates the presence of additional processes (e.g. departure from Keplerian velocity of the charged ring particles), which will be discussed. We will further discuss the likely connection between the observed lagging field configuration in the middle magnetosphere and in the inner magnetosphere.  
Using multi-temporal Sentinel-2 data to predict chemical properties of the organic surface layer of forest soils
Authors: Becker Carina , Frantz David , Petzold Rainer , Schmidt Karsten , Behrens Thorsten , Scholten Thomas
Published: March 2020

Area-wide high resolution information of organic layer properties is required for assessing the current nutrient availability in forest stands. Together with climate, location, parent material and terrain predictors, vegetation is known to have a direct impact on the characteristics of the organic surface layer of forest soils and therefore plays an important role in predicting its chemical properties.

Here, we use multi-temporal Sentinel-2 (S2) Earth Observation (EO) data as a proxy for various vegetation characteristics to spatially predict forest organic layer properties at 10 m spatial resolution in Saxony/Germany. To ensure full data coverage of the study area, we used multi-temporal statistical measures of S2 data generated by the FORCE algorithm. Complementary to ancillary predictors (climate, location, parent material, terrain), we compared three different sets of vegetation related data as predictors: (1) categorical tree species groups from a field survey, (2) multi-temporal statistical measures derived from S2 data and (3) S2 multi-temporal statistical measures and additional S2 multi-temporal spectral indices.

We used random forest regression models to estimate pH value, base saturation, C/N ratio and effective cation exchange capacity of the organic surface layer and the upper 0-5 cm of the first mineral soil horizon. For model evaluation 5-times 10-fold cross-validation was applied. For predictor evaluation and selection, we used recursive feature elimination.

The results indicate that S2 data can serve as a vegetation proxy when predicting forest organic layer properties. For example, the cross-validation estimate of the prediction error in scenario (3) for C/N ratio (organic surface layer) is about 7.3 % lower than in scenario (1). In some cases the explanatory power is higher compared to the field survey data of the tree species groups, probably due to the high local variability of EO based data. This may help to reveal short range variability of chemical properties. We conclude that the three scenarios show comparable results and thus multi-temporal S2 data can be used as a vegetation proxy to spatially predict chemical properties of the organic surface layer of forest soils.
Automatic Picking of Teleseismic P- and S-Phases using an Autoregressive Prediction Approach
Authors: Stampa Johannes , Timkó Máté , Tesch Marcel , Meier Thomas
Published: March 2020

In the recent decade, the amount of available seismological broadband data has increased steeply. Picking later arriving phases such as S-phases is difficult, and there are few manual picks available for these phases. Data sets of manual picks can also be problematic, since phase arrival picks are sensitive to the parameters of the filtering, which are often unknown, and the individual picking behavior of the analysts. This neccesitates the adoption of automatic techniques for determining teleseismic phase arrival times consistently over a large data set.

In this work, a robust automatic picking algorithm based on autoregressive prediction in a moving window is explained. In this algorithm, a characteristic function is calculated as the autoregressive prediction error in a moving window. This characteristic function is then transformed with the Akaike-Information Criterion to obtain the phase arrival time estimate. This estimate is further improved in a second iteration of a similiar scheme in a smaller time window.

The algorithm is applied to a global data set including AlpArray stations, covering a time period from 1995 to present, to obtain arrival times for teleseis- mic P- and S-phases. Residuals to theoretical travel times and to local averages are shown. Different methods for automatically evaluating the quality of indi- vidual picks are used, based on signal to noise ratio of the seismic trace and impulsiveness of the arrival. The picking errors are estimated by comparision with manual picks and neighboring stations as well as statistical methods. The quality evaluations suggest potential of using these automatically determined phase arrival times for a travel time tomography.
Empirical Formulation for number of ice crystal fragments by sublimational breakup
Authors: Deshmukh Akash , Phillips Vaughan
Published: March 2020

There is much uncertainty about high concentrations of ice observed in clouds and their origins. In the literature, there have been previous experimental studies reported about the sublimation process of an ice crystal causes emission of fragments by breakup.   Such sublimational breakup is a type of secondary ice production, which in natural clouds can cause ice multiplication. 

To represent this process of sublimation breakup in any cloud model, the present study proposes a numerical formulation of the number of ice fragments generated by sublimation of pristine ice crystal. This is done by amalgamating laboratory observations from previous published studies. The number of ice fragments determined by relative humidity (RH) and initial size of the ice particle were measured in the published experiments, and by simulating them we are able to infer parameters of a sublimation breakup scheme.   At small initial sizes, the dependency on size prevails, whereas at larger sizes both dependencies are comparable. This formulation is compared with observations to see the behaviour of it.
Spectral Calibration of the SLSTR Focal Plane Assemblies
Authors: Nightingale Tim , McPheat Robert , Lee Arrow , Polehampton Ed , Pedretti Ettore , Mortimer Hugh
Published: March 2020

We describe a novel technique – Fourier transform spectroscopy – that we have developed to characterise the spectral and polarisation responses of the Sentinel-3 SLSTR optical channels. Our method has a number of advantages over conventional approaches employing a grating monochromator, including excellent spectral registration and resolution, intrinsic rejection of self-emission from the test setup and fast measurement times. Our measurements are traceable, through the spectral responsivity of a reference detector and the wavelength of a HeNe laser, to national standards.

We illustrate our method with sample results from the spectral calibrations of the four SLSTR focal plane assemblies tested to date. 
Reactive transport in porous media with local mixing limitation: A Lagrangian modeling approach
Authors: Sole-Mari Guillem , Fernàndez-Garcia Daniel , Sanchez-Vila Xavier , Bolster Diogo
Published: March 2020

Hydrological models are unable to fully resolve subsurface flow and transport down to the microscale. Instead, modelers usually work with upscaled flow and transport properties that represent the behavior of the system at a given coarse scale. While this approach is justified from a practical standpoint, it disregards the local heterogeneity of porous media flows, which tend to produce mixing-limited reactive transport behaviors that cannot be captured by classical modeling approaches. While some innovative methods have been suggested in the past in order to address this problem, none of them has proposed a mathematical formulation which can potentially reproduce the generation, transport and decay of local concentration fluctuations and their impact on chemical reactions, for general initial and boundary conditions. Here, we propose a Lagrangian approach based on the random motion of fluid particles that locally mix following a Multi-Rate Interaction by Exchange with the Mean (MRIEM) formulation. Concentration fluctuations in the proposed model display the typical behavior associated to transport in porous media with mixing-limited conditions. Experimental results of reactive transport are successfully reproduced by the model.
Performance of ECCC surge forecasting systems near Canada's East Coast during the passage of hurricane Dorian
Authors: Huziy Oleksandr , Natacha Bernier , Pouliot Benoit , Timko Patrick , Wan Pengcheng , Telford Devon
Published: March 2020

Accurate forecasts of storm surges caused by winds and atmospheric pressure are important for the protection of life and property in coastal regions and also for safe navigation. Therefore, Environment and Climate Change Canada (ECCC) maintains and develops surge prediction systems. This study focuses on the assessment of the timing and amplitude of predicted surges at selected locations during the passage of hurricane Dorian. The systems use barotropic ocean models to simulate water levels and currents at 1/30 and 1/12 degree horizontal resolutions.

The relatively low tidal range at the time of Dorian’s landfall helped prevent catastrophic flooding. However, with a closer superposition of the peak surge and high tide, the damage could have been more significant. Reasonably well predicted timing of the highest surge by the system helped prevent the over-issuance of warnings. Sensitivity of the forecast quality to the lead time, resolution and atmospheric forcing for the event will be presented.
Coastal boulder fields and tsunami hazards of East Java, Indonesia
Authors: Meservy William , Harris Ronald , Setiadi Gilang , Hapsoro Satrio
Published: March 2020

Coastal boulder deposits are records of unusually powerful wave action events associated with either storms or tsunamis. Our 2016 paleotsunami survey of the southeastern Java coast led to the discovery of five coastal boulder fields near Pacitan, Indonesia, possibly dating to the mid-to-late 19th century or prior, and two similar fields at Pantai Papuma and Pantai Pasir Putih that were tsunami-emplaced during the 1994 7.9 Mw event in East Java. Both multiyear photogrammetry and hydrodynamic wave height reconstructions of the accumulations near Pacitan suggest the boulders were likely tsunami rather than storm-wave emplaced. We evaluate the boulders as an inverse problem, using reconstructed wave heights and ComMIT tsunami modelling to suggest a minimum 8.4 Mw earthquake necessary to dislodge and emplace the largest boulders near Pacitan assuming they were all deposited during a single seismic event and that the rupture source was located along the Java Trench, some 200 km south of Pacitan.
﻿Climate Index Metadata and its Implementation
Authors: Zimmermann Klaus , Bärring Lars
Published: March 2020

Climate indices play an important role in the practical use of climate and weather data. Their application spans a wide range of topics, from impact assessment in agriculture and urban planning, over indispensable advice in the energy sector, to important evaluation in the climate science community. Several widely used standard sets of indices exist through long-standing efforts of WMO and WCRP Expert Teams (ETCCDI and ET-SCI), as well as European initiatives (ECA&D) and more recently Copernicus C3S activities. They, however, focus on the data themselves, leaving much of the metadata to the individual user. Moreover, these core sets of indices lack a coherent metadata framework that would allow for the consistent inclusion of new indices that continue to be considered every day.

In the meantime, the treatment of metadata in the wider community has received much attention. Within the climate community efforts such as the CF convention and the much-expanded scope and detail of metadata in CMIP6 have improved the clarity and long-term usability of many aspects of climate data a great deal.

We present a novel approach to metadata for climate indices. Our format describes the existing climate indices consistent with the established standards, adding metadata along the lines of existing metadata specifications. The formulation of these additions in a coherent framework encompassing most of the existing climate index standards allows for its easy extension and inclusion of new climate indices as they are developed.

We also present Climix, a new Python software for the calculation of indices based on this description. It can be seen as an example implementation of the proposed standard and features high-performance calculations based on state-of-the-art infrastructure, such as Iris and Dask. This way, it offers shared memory and distributed parallel and out-of-core computations, enabling the efficient treatment of large data volumes as incurred by the high resolution, long time-series of current and future datasets.
Imaging laboratory rupture nucleation at the source: A friction experiment using ultrafast ultrasound
Authors: Aichele Johannes , Latour Soumaya , Catheline Stefan , Roux Philippe
Published: March 2020

At the field scale and in most laboratory studies the rupture nucleation mechanism of an earthquake, landslide or glacier stick-slip cannot be directly imaged. Near-field and source effects are thus difficult to observe. We use correlation of highspeed ultrasound images to track shear wave propagation at the rupture nucleation source and in its near-field. The particle velocity and accumulated displacement of the shear wave field emitted by the rupture are observed in-situ on a very dense grid. The grid consists of the ultrasonic imaging plane inside the frictional body and resolution is defined by the ultrasonic wavelenth (0.3 mm). The rupture process is generated by controlling a driving slab through a motor and a granular layer of sand or gravel constitutes the stick-slip behavior. The frictional body is a homemade Poly-Vinyl-Alcohol hydrogel. Although its properties are differing from those of classically investigated rocks, it constitutes a linear elastic material and reproduces rupture processes that are known from the field and rock physics. Through the elastic wave field we observe microslips which precede supershear rupture propagation along the frictional interface. We experimentally show that the source mechanism of a breaking asperity depends on the material contrast of the adjacent halfspaces. Neither a double-couple nor a single-force mechanism perfectly reproduce the experimental data of a rupturing asperity, while micro-slips are well reproduced by a singular shear point force.
Soil Moisture Initialization Input Scale Effect on Parameter Value Identification of a Physically Based Distributed Hydrologic Modelling
Authors: Pradhan Nawa Raj , Brown Steven , Floyd Ian
Published: March 2020

Data acquisition and an efficient processing method for hydrological model initialization, such as soil moisture, and parameter value identification are critical for a physics based distributed watershed modelling of flood and flood related disasters such as sediment and debris flow. Site measurements can provide relatively accurate estimates of soil moisture, but such techniques are limited due to the need for a variety of measurement accessories, which are difficult to obtain to cover a large area sufficiently. Available satellite-based digital soil moisture data is at 9 kilometers to 50 kilometers in resolution which completely filters the soil moisture details at the hill slope scale. Moreover, available satellite-based digital soil moisture data represents only a few centimeters of the top soil column that informs nothing about the effective root-zone wetness. A recently developed soil moisture estimation method called SERVES (Soil moisture Estimation of Root zone through Vegetation index-based Evapotranspiration fraction and Soil properties) overcomes this limitation of satellite-based soil moisture data by estimating distributed root zone soil moisture at 30 meter resolution. In this study, a distributed watershed hydrological model of a sub-catchment of Reynolds Creek Experimental Watershed was developed with GSSHA (Gridded Surface Sub-surface Hydrological Analysis) Model. SERVES soil moisture estimated at 30 meter resolution was deployed in the watershed hydrological parameter value calibration and identification process. The 30 meter resolution SERVES soil moisture data was resampled to 4500 meter and 9000 meter resolutions and was separately employed in the calibrated hydrological model to determine the effect soil moisture resolution  has on the simulated outputs and the model parameters. It was found that the simulated discharge significantly decreased as the initial soil moisture resolution was coarsened. To compensate for this underestimated simulated discharge, the soil hydraulic conductivity value decreased logarithmically with respect to the decreased resolutions. This study will reduce parameter value identification uncertainty especially in flood and soil erosion modelling at multi scale watershed in a changing climate.
Impacts of thermokarst on permafrost carbon losses and ecosystem services
Authors: Turetsky Merritt , Gibson Carolyn , Dieleman Catherine
Published: March 2020

Permafrost thaw is altering northern ecosystems and the services they provide at scales ranging from local subsidence to global climate feedbacks. In organic-rich peatlands, thermokarst initiation and spread rates are increasing with rising mean annual air temperatures, changes in wildfire, and human land use. This presentation will outline empirical and modeling approaches to better understand the consequences of thermokarst in peatlands as well as other types of northern terrains on carbon cycling, wildlife, and other aspects of ecosystem services.  We are using fine scale datasets and remote sensing to map thermokarst coverage and expansion in both the Northwest Territories, Canada and interior Alaska. Using chronosequences and regional gradients, we are studying thermokarst impacts along gradients of time-since-thaw. Through a Permafrost Carbon Network synthesis, we developed conceptual and numerical models to understand how thermokarst development (formation, stabilization, re-accumulation of permafrost in some conditions) affects carbon storage and release. We are using a combination of empirical and modelled data to test hypotheses about climatic, ecological, and Quaternary controls on thermokarst rates and subsequent impacts on ecosystem services. We demonstrate that thermokarst in peat-rich landscapes are hotspots for permafrost carbon release primarily through methane emissions, have the potential to impact hunter movement and safety, and affect caribou habitat quality.
Self-similar solution analysis of hydraulic fracture growth with bottom hole pressure restriction
Authors: Paderin Grigory
Published: March 2020

Nowadays hydraulic fracturing is an essential part of the development of low-permeability oil and gas fields. Moreover, the well productivity dynamics is radically depends on the effectiveness of fracturing treatment. One of the main hydraulic fracturing design problem is create a long fracture without crack height growth into the intervals saturated with non-target fluid (e.g. water). The obtaining self-similar solution to this problem in the framework of the Pserudo3D [1-3] model is considered in the presented study.

The presented crack propagation analysis shows that in the case of constant bottom hole pressure the automodel solution of one variable could be derived. A study on the dependence of the solution on pressure, time, hydraulic fluid properties and leak off is also conducted.

REFERENCES
[1] J.I. Adachi, E. Detournay, and A. P. Peirce // Analysis of the classical pseudo-3D model for hydraulic fracture with equilibrium height growth across stress barriers. International Journal of Rock Mechanics and Mining Sciences. 2010. 47 (4): 625–639. 
[2] X. Weng, O. Kresse, C. Cohen, R. Wu, and H. Gu // Modeling of hydraulic-fracture-network propagation in a naturally fractured formation. SPE Production & Operations  2011. 26 (4): 368–380. doi:10.2118/140253-PA.
[3] G.V. Paderin // Proxy Pseudo3D model: the optimum of speed and accuracy in hydraulic fracturing simulation. IOP Conference Series: Earth and Environmental Science. 2018.
Effect of climate warming on the mixed layer depth in lakes
Authors: Shatwell Tom , Kirillin Georgiy
Published: March 2020

The surface mixed layer in lakes is where phytoplankton grow and where most of the primary production occurs. Knowledge of the thickness of the mixed layer is essential to estimate for instance primary productivity and to interpret remote sensing measurements, because it determines the mean light supply and indicates how homogeneous the water column is. Modelling studies, primarily in the ocean, have concluded that the mixed layer will shoal as a result of climate warming, but the empirical evidence does not support this. Here we seek to determine how climate change affects the mixed layer thickness and mean underwater irradiance in lakes. We use an ensemble modelling approach to simulate mixed layer depth in 3 warming scenarios (RCP2.6, 6.0, 8.5) in about 50 lakes across the globe using the hydrodynamic model Flake forced by four downscaled global climate models. Results indicate that warming has little direct effect on the mixed layer depth. Mean underwater light in the mixed layer was nevertheless projected to increase as a result of the global radiation increases in the global climate models.
The impact of lianas on radiative transfer and albedo of tropical forests
Authors: Meunier Félicien , Shiklomanov Alexey , Dietze Michael , Visser Marco , Verbeeck Hans
Published: March 2020

Forest albedo changes with vegetation dynamics, ecosystem demography and succession as different plant species can be characterized by contrasting leaf traits, as well as different allocation strategies. In tropical ecosystems, lianas (woody vines) strongly impact the forest biogeochemical cycles by competing with co-occurring trees for above- and below-ground resources. In addition to the particular location of their foliage (often at the top of the canopy), lianas were shown to contrast with tropical trees in terms of biochemical and structural leaf properties, as well as allocation strategies. As a consequence, liana spectral signature differs in several regions of the leaf spectrum (visible, near infrared and shortwave infrared) from tree’s one. At larger scale, the forest canopy reflectance spectrum is also affected by the relative abundance of lianas.

To evaluate the impact of lianas on the radiative transfer and albedo of tropical forests, we collected all published reflectance spectra of liana and co-occurring tree leaves as well as the canopy reflectance spectra characterized by high and low liana coverage. We then calibrated both a leaf (PROSPECT-5) and a canopy (ED2-RTM) radiative transfer model on those data to reproduce the spectral signatures together with their differences, for each single study and site. The Bayesian framework that we used generated leaf biochemical and structural trait distributions, as well as allocation pattern strategies that could be compared between both growth forms.

Collected spectra could be fairly well reproduced at both leaf and canopy levels by the selected mechanistic models. In most studies, calibration led to significantly lower chlorophyll and carotenoid contents, higher relative water content, and larger specific leaf areas for liana leaves, which allowed reproducing observed higher leaf reflectance values in the visible and shortwave infrared and the lower ones in the near infrared.  We then validated our findings with independent field data on leaf chemistry and structure from the same studies.

These calibrated radiative transfer models are tools that can be used in future research to investigate the liana impact on the global energy budget of tropical forests, as well as to monitor spatial and temporal liana abundance.
The effect of extreme drought events on Pinus sylvestris (L.) xylem plasticity in pure and mixed forests and contrasting climatic conditions
Authors: Giberti Giulia Silvia , Tonon Giustino , Giammarchi Francesco , Giovannelli Alessio , Bielak Kamil , Ariza Ana Martín , Alonso Cristobal Ordóñez , Bravo Felipe , du Toit Ben , Uhl Enno , Camilla Wellstein
Published: March 2020

Forest ecosystems are known to be vulnerable to climate change. Climate extremes, such as drought
events, are expected to increase in duration and frequency in many areas across the globe. Unexpected
and prolonged drought events already caused forests dieback all over the world in the last decades,
leading to dramatic consequences, such as biodiversity loss, ecosystem services alteration and reduction
of carbon sequestration potential. Indeed, in Central Europe, monocultures consisting mostly of 
secondary conifer forests, showed low resistance to such events, and their viability is further threatened
by the interaction with other biotic and abiotic factors. In this context, the need of a deeper understanding
of the physiological mechanisms behind the tree response to extreme drought eventsis fundamental. The
present study, developed under the network of the CARE4C Project (Carbon smart forestry under climate
change GA 778322), aims at investigating Pinus sylvestris xylem plasticity in response to extreme drought.
We selected P. sylvestris pure forests in contrasting climatic zones of Europe, i.e. continental (Poland) and
Mediterranean (Spain), to study P. sylvestris xylem plasticity to extreme drought events under different
climatic conditions. Contemporarily, this study aims at comparing the xylem plasticity of P. sylvestris in
mono-specific and mixed forests. In the latter, the admixture is with Quercus petraea and Quercus
pyrenaica, in Poland and Spain respectively. The responses of P. sylvestris wood anatomical traits, such as
tracheid lumen area, cell wall thickness and parenchyma ray area, will be quantified along the entire treering chronologies. Short-term and legacy effects of extreme drought on P. sylvestris wood anatomical
traits will be evaluated in order to provide insights about the vulnerability of this speciesin a future climate
scenario. Locally, the comparison between P. sylvestris wood anatomical traitsin mono-specific and mixed
forests will highlight whether the mixing of species with different ecological needs can affect P. sylvestris
performance, ameliorating the resilience of this species to extreme drought events.
Combining Indigenous and Scientific Forecast for Improved Climate Services in Ghana
Authors: Nyadzi Emmanuel , Werners Saskia , Biesbroek Robbert , Ludwig Fulco
Published: March 2020

Extreme weather events and climate change are affecting the livelihoods of farmers across the globe. Accessible and actionable weather and seasonal climate information can be used as an adaptation tool to support farmers to take adaptive farming decisions. There are increasing calls to integrate scientific forecast with indigenous forecast to improve weather and seasonal climate information at local scale. In Northern Ghana, farmers lament about the quality of scientific forecast information thereby depending on their own indigenous forecast for taking adaptive decisions. To improve this, we developed an integrated probability forecast (IPF) method to combine scientific and indigenous forecast into a single forecast and tested its reliability using binary forecast verification method as a proof of concept. We also evaluated the acceptability of IPF among farmers by computing an index from multiple-response questions with good internal consistency check. Results show that, for reliability, IPF on average performed better than indigenous and scientific forecast at a daily timescale. At seasonal timescale, indigenous forecast overall performed better followed by IPF and then scientific forecast. However, IPF has far greater acceptability potential.  About 93% of farmers prefer IPF method as this provides a reliable forecast, requires less time and at the same time helps deal with contradicting forecast information. Results also show that farmers already use insights from both forecasts (complementary) to inform their farm decisions. However, their complementary method does not resolve the issues of contradicting forecast information. We conclude that, as a proof of concept, integrating indigenous and scientific forecast has high acceptability and can potentially increase forecast reliability and uptake.

 

 

 
Instabilities in extensional flows and the dynamics of rifts in ice-shelves
Authors: Stern Lielle , Sayag Roiy
Published: March 2020

Ice shelves that spread into the ocean can develop rifts, which can trigger ice-berg calving and enhance ocean-induced melting. Fluid mechanically, this system is analogues to the propagation of a non-Newtonian, strain-rate-softening fluid representing ice that displaces a relatively inviscid and denser fluid that represents an ocean. Recent scaled laboratory experiments have shown that when the flow geometry is circular the front of the displacing non-Newtonian fluid, which represents the leading edge of a shelf, can become unstable and evolve finger-like patterns comprised of rifts and tongues (Sayag & Worster, 2019a). As the rifts and tongues evolved, their number declined with time through the closure of some rifts.

In this study we focus on the weakly nonlinear stability of the propagating front. We consider an annular ice shelf having a fixed grounding line and an edge that evolves due to constant mass flux across the grounding line. We investigate the time evolution of the perturbed front to quantify the instability mechanism and the reduction of the number of rifts and tongues over time. The model predictions have better agreement with experimental measurements than previous studies. Our analysis elucidates the formation and evolution of rifts in ice shelves and provides testable predictions.
Labrador Sea waters export routes in an idealised model and a global high-resolution ocean model
Authors: Katsman Caroline , Georgiou Sotiria , Sayol Juan-Manuel , Ypma Stefanie , Brüggemann Nils , Dijkstra Henk , Pietrzak Julie
Published: March 2020

The water masses exiting the Labrador Sea, and in particular the dense water mass formed by convection (i.e. Labrador Sea Water, LSW), are important components of the Atlantic Meridional Overturning Circulation (AMOC). Several studies have suggested that the eddy activity within the Labrador Sea is of high importance for the properties of the LSW and the export routes. In this study, the pathways and the associated timescales of the water masses exiting the Labrador Sea are investigated by using a Lagrangian particle tracking tool. This method is applied to two different model simulations: to an eddy- permitting idealized model able to reproduce the essential features of the Labrador Sea, and to a high-resolution global ocean model simulation under a repeated annual climatological forcing.

In both model configurations, the Lagrangian trajectories reveal that the water masses that exit the Labrador Sea have followed either a fast route within the boundary current or a slow route that involves extensive boundary current-interior exchanges. Regions characterized by enhanced eddy activity play a significant role in determining the properties and the timescales of the water masses exiting the marginal sea, as the interior-boundary current exchange is governed by eddy activity.

Analysis of the properties of the water masses along the different pathways shows that the water masses that pass through the interior experience stronger densification than those that follow the boundary current.

This study highlights the importance of the exchanges between the boundary current and the convection area in the interior in setting the properties of the water masses that leave the Labrador Sea and the associated timescales.
Analysis of Baseline and Perimeter Air Monitoring Data from the Calaveras Dam Replacement Project (CDRP), Fremont, California
Authors: Erskine Bradley , Bailey Mark
Published: March 2020

This paper presents the results of 810 pre-project baseline samples collected over four years (2010-2011), and 7,210 offsite (ambient) and 14,314 perimeter samples collected over 7 years (2012-2018) during the CDRP project. The principal asbestos particles were chrysotile from serpentinite, and glaucophane-winchite amphibole from blueschist. The baseline data showed that asbestos concentrations measured at each station are not representative of a regional average background, rather, they reflect contributions from several variables such as: location on or near NOA-containing units, wind direction, intensity of localized soil disturbance, and time of year. The data shows that baseline sampling prior to a project cannot be used as a measure of “background” during the project. The analysis of amphibole composition in air and rock/soil samples was applied to differentiate local source impacts from the primary CDRP asbestos emissions. Of particular value was the application of the calcic-amphibole to total amphibole ratio (Ca index) measured during ABS sampling and comparison with the ratios measured in the samples. This analysis delineated three primary amphibole sources: 1) alluvium in the Sunol Valley with a high Ca index, 2) imported road surfacing material with a moderate Ca index, and 3) blueschist with a low Ca index. When the data was sorted by wind direction, the analysis showed that the contribution of CDRP-generated asbestos to monitoring stations was significant near the point of disturbance only, and did not significantly impact offsite stations that were located at or near sensitive receptors. The asbestos measured at the offsite stations were correlated with local geologic units. The analysis verified that the CDRP emissions were well below the project-specific risk-based thresholds established for the CDRP project, documenting that the offsite receptors were not exposed to an adverse risk by CDRP activities.
Forecasting plastic mobilization during extreme hydrological events
Authors: Roebroek Jasper , Harrigan Shaun , van Emmerik Tim
Published: March 2020

Plastic pollution of aquatic ecosystems is an emerging environmental risk. Land-based plastics are considered the main source of plastic litter in the world’s oceans. Quantifying the emission from rivers into the oceans is crucial to optimize prevention, mitigation and cleanup strategies. Although several studies have focused on estimating annual plastic emission based on average hydrology, the role of extreme events remains underexplored. Recent work has demonstrated that floods can mobilize additional plastics. For example, the 2015/2016 UK floods resulted in a 70% decrease of microplastic sediments in several catchments. In this project, the use of the Global Flood Awareness System (GloFAS) flood forecasting system to assess additional mobilization of plastic pollution will be explored.
Aim, activities and early outcomes of the Coastal Working Group of the European Global Ocean Observing System (EuroGOOS)
Authors: El Serafy Ghada ,   EuroGOOS Coastal Working Group
Published: March 2020

The major interface between humans and the ocean occurs in the coastal seas. Marine industries thrive in this area while European citizens make daily use of the coastal ocean for tourism, leisure and recreation. Operational oceanography assists both industry and the general public to make decisions about their use of and access to the coastal ocean. The EuroGOOS community has developed, based on in-situ and satellite observations, data and modelling capacities, a wide range of products and services for such use cases. 
The EuroGOOS Coastal working group examines the entire value chain from coastal observations, satellite data, ocean forecasts and analysis, to products and services for coastal users. The working group reviews sustainability and fitness for purpose of the existing system and identifies gaps and future steps needed to secure and improve all elements of the coastal value chain. The EuroGOOS Coastal Working Group builds upon significant initiatives already completed or underway that have focused on coastal observatories. These include, but are not limited to, the work of EMODnet, SeaDataNet, CLMS, and CMEMS-In Situ Thematic Centres (INS TACs), which play significant role in making available key datasets for coastal areas, the JERICO-NEXT and JERICO-S3 EC projects, which work towards sustaining the JERICO-RI on long term, as well as activities within EuroGOOS working groups, platforms task teams, and the five regional operational oceanographic systems (ROOS). 
More specifically, the main activities of the EuroGOOS Coastal Working Group are: (i) mapping primary users of coastal products, (ii) reviewing available and potential coastal data sources with special focus on river discharges, (iii) preparing a comprehensive inventory of European operational models, (iv) reviewing coastal data assimilation frameworks for optimizing coastal sea monitoring and forecasting systems, (v) preparing an inventory of integrated coastal products and services, and (vi) formulating a EuroGOOS roadmap for the enhanced integration of coastal services into a EuroGOOS Coastal Working Group White Paper. 
The outcomes of the EuroGOOS Coastal Working Group activities are primarily designed to support four specific areas of the EuroGOOS Strategic Agenda 2020 and the short-term priority areas, namely (1) sustained fit for purpose observations, (2) data matters, (3) product development and (4) communication and outreach. On the other hand, in broader sense these activities contribute to the coastal community through peer reviewed articles such as the review of operational modelling capacity in European Seas (Capet et al., submitted) and by promoting collaboration to initiate new opportunities to effectively serve the coastal users in the industry (e.g. aquaculture sector) as in the H2020 FORCOAST project (www.forcoast.eu). 
Human land-use change and biodiversity trends in the British Isles
Authors: Woodbridge Jessie , Fyfe Ralph , Pelling Ruth , Smith David , DeVareilles Anne
Published: March 2020

Conservation and promotion of biodiverse landscapes is a major target for ecological conservation and landscape management, as biodiversity is a key determinant of ecosystem functioning. Recent accelerations in the intensity of human land-use have been implicated for changes in biodiversity, but the relationships between land-use change and diversity are complex, include important historical legacies and major transformations are likely to have occurred across much longer time-scales than those covered by direct observation records. This collaborative research between Historic England and the Universities of Plymouth and Birmingham, is synthesising palaeoecological datasets from across the British Isles from both the natural and archaeological sciences to reconstruct biodiversity patterns and evaluate relationships between these patterns and land-use over multi-millennial time-scales. The fossil remains of plants, pollen and insects preserved in sediments are being compared and critically evaluated with the aim to provide valuable information about past land-use strategies, biodiversity, habitat resilience to disturbance and recovery rates. Exploring environmental change within the context of the Holocene (the last 11,700 years) allows comparison of ecosystem states across a wide range of land-use strategies, from hunter-gathering to complex patterns of land-use in later prehistoric and historical periods.