bluuebunny/crossref_metadata_2025 huggingface dataset:
Vegetation change in response to climate change and human activities in a typical alpine region on Tibetan Plateau
Authors: Zhao Guosong
Published: March 2022

The study of attribution analysis and sustainability of vegetation dynamics is of great significance to assess effectiveness of ecological engineering, make policies of adaptive ecological management, and improve ecological environment. By using datasets of MODIS NDVI, annual temperature and precipitation datasets, and land cover datasets, methods such as trend analysis, multiple regression residuals analysis, Hurst index analysis were employed to distinguish interannual change of vegetation dynamics during 2000-2020, determine contributions of climate change and human activities on vegetation dynamics, and assess sustainability of vegetation dynamics in Gannan Prefecture (a typical alpine region on Tibetan Plateau), which is located in Gansu Province of China, especially in ecological restoration project areas. The results showed that NDVI increased at a rate of 2.4×10-3/a during the growing season across 2000-2020, showing vegetation improvement in most parts of the study area, and only a few sporadically degraded areas, and the increasing rate was the fastest in the Grain to Green Project. Clear spatial pattern about the effects of climate change and human activities on vegetation change was found, which is the southern part mainly affected by climate change, while the northern part dominated by human activities, and their contributions to vegetation change were 52.32% and 47.68%, respectively. Among ecological restoration projects, Grain to Green Project (59.89%) was most obviously affected by human activities. Moreover, the main future trend of vegetation change in Gannan was continuous improvement through Hurst index analysis. In the future, more attention should be paid to the areas with conditions of present improvement and future anti-sustainability as well as present degradation and future sustainability.
Analysis of wind wave statistics preceding beach cast events on the southeastern shore of the Baltic Sea (Kaliningrad region): preliminary results
Authors: Isachenko Igor , Esiukova Elena
Published: March 2022

Beach cast is a material deposited on beaches after being washed up by storm (or tidal movement). The composition of beach cast usually includes seagrass or algae fragments, wracks of land plants and other materials of natural origin, (anthropogenic) marine litter, including plastic debris and microplastics. Beach casts monitoring is of current interest for beach management and maintenance of the sandy shores for recreational purposes, tracing marine litter transport and dispersion, evaluating environmental contamination by microplastiсs.

Large patches of marine debris appear on beaches after stormy weather. However, little is known about the sea state that precedes the formation of beach casts. From an observer's point of view, beach casts occur at random locations along the coast at unpredictable times. They may even be washed back to the sea at some time later. This work aims to disclose characteristic features of temporal variations of surface wave field parameters, which lead to beach cast formation.

Results of incidental surveys of the northern coast of the Sambia Peninsula, stretching from west to east in the southeastern part of the Baltic Sea, were analyzed. The presence of beach cast (at one or more locations) was observed during 234 days of 2011-2021. Some of the observations were performed during or shortly after the ending of the beaching process. Field information was collated with a freely available re-analysis database on surface waves (http://marine.copernicus.eu). Surface wave spectrum parameters were picked up from the database at the geographical point corresponding to the coastal zone's open-sea limit. Elements of Bayesian analysis were applied to overcome the lack of information on the very time of the beach casts formation and/or the unknown duration of the beaching process.

The analysis shows the values of significant wave height, peak period, and wave direction, which occurred before the beach cast appearance more often than follows from the overall time statistics ("climate"). A separate analysis of only recently formed beach casts made it possible to determine the evolution of wave spectrum parameters during the beaching process. Data suggests that most of the beach cast events on this coast are preceded by waves caused by cyclone passages from the northern direction.

Data analysis is carried out by I.I., with the support of the Russian Science Foundation, grant No 21-77-00027. Beach surveys are carried out by E.E. voluntarily and with partial support from IO RAS state assignment.
Reconstruction of tectonically driven Quaternary fluvial dynamics of the Western Kura Fold-Thrust Belt (Eastern Caucasus, Georgia)
Authors: Sukhishvili Lasha , Boichenko Giorgi , Merebashvili Giorgi , Javakhishvili Zurab , Forte Adam , Godoladze Tea
Published: March 2022

Since the Plio-Pleistocene, southward migration of shortening in the Eastern part of the Greater Caucasus (GC) into the Kura foreland basin has formed the Kura fold–thrust belt (KFTB) and Alazani piggyback basin between the GC and KFTB, modifying the drainage network within the southern foreland. The northern, eastern and south-eastern flanks of the Western KFTB (Gombori range) expose the predominantly alluvial Alazani series, while the central (highest) part of the range is covered by Tsivi suite. The base of the Alazani series is estimated to be 2.7-2.5 Ma and deposition spanned the Akchagyl and Apsheronian regional stages. The KFTB likely initiated during the Akchagyl-Apsheronian period, and thus the paleocurrents of the alluvial Alazani series sediments represent potential archives for tracking resulting drainage reorganization within the foreland. Previous measurements of paleocurrents from the Alazani series revealed a reversal from south to north flow directions, but the measurements were limited to the northern flank of the Gombori range. Here we present new observations from the central and southern flanks of the Gombori. Results from the eastern and southeastern regions are consistent with the currents from the northern flank, but paleocurrents from the Tsivi suite are more complex and raises additional questions regarding its depositional context and age. The new results help to build a more complete picture of fluvial dynamics driven by Quaternary tectonic deformations within the GC foreland.
Secondary School Teacher’s Awareness of Climate Change: a comparison of pre-service and in-service teachers from the Spanish North African city of Melilla
Authors: López-Quirós Adrián , Guilarte Veronica
Published: March 2022

The consequences of climate change present one of the most pressing issues of our time. It is important to have a well-informed population about the consequences of climate change in order to prepare them to make decisions about it. In this sense, along with the contribution of the media, climate change education (climate literacy) is crucial for the development of climate change knowledge and beliefs. A solid knowledge about climate change not only helps teachers to successfully meet the goal of climate literacy, but also influences student's attitudes regarding practical steps to reduce the impacts of anthropogenic climate change.

A sample of seventy-four pre-service teachers (Master’s students – ‘Master's Degree in Secondary Education, Baccalaureate, Vocational Training and Language Teaching’ at the University of Granada, Melilla Campus), and sixty-nine in-service teachers (from Melilla), allowed to analyse: (1) knowledge, (2) beliefs, and (3) attitudes about climate change. Regarding the study of the first concept, the following items were assessed: (a) knowledge about the causes of climate change, (b) knowledge about the greenhouse effect, (c) knowledge concerning the expected consequences of climate change, and (d) action-related knowledge about climate change. The results presented in this study display that most of the pre- and in-service teachers (from both the scientific itinerary and other itineraries) believe in the existence of climate change and recognize its anthropic cause. However, they still respond to different misconceptions as well as distorted knowledge about the consequences of climate change, affecting their willingness to act on it. Consequently, the Secondary School Curriculum needs to be updated, since it is mainly focused on the scientific explanations of the phenomenon rather than on the social or practical aspects of the problem.
Ultrasonic Scattering and Absorption Imaging for the Reinforced Concrete using Adjoint Envelope Tomography
Authors: Zhang Tuo , Sens-Schönfelder Christoph , Epple Niklas , Niederleithinger Ernst
Published: March 2022

Seismic and ultrasound tomography can provide rich information about spatial variations of elastic properties inside a material rendering this method ideal for non-destructive testing. These tomographic methods primarily use direct and reflected waves, but are also strongly affected by waves scattering at small-scale structures below the resolution limit. As a consequence, conventional tomography has the ability to unveil the deterministic large-scale structure only, rendering scattered waves imaging noise. To image scattering and absorption properties, we presented the adjoint envelope tomography (AET) method that is based on a forward simulation of wave envelopes using Radiative Transfer Theory and an adjoint (backward) simulation of the envelope misfit, in full analogy to full-waveform inversion (FWI). In this algorithm, the forward problem is solved by modelling the 2-D multiple nonisotropic scattering in an acoustic medium with spatially variable heterogeneity and attenuation using the Monte-Carlo method. The fluctuation strength ε and intrinsic quality factor Q-1 in the random medium are used to describe the spatial variability of scattering and absorption, respectively. The misfit function is defined as the differences between the full squared observed and modelled envelopes. We derive the sensitivity kernels corresponding to this misfit function that is minimized during the iterative adjoint inversion with the L-BFGS method. This algorithm has been applied in some numerical tests (Zhang et al., 2021). In the present work, we show real data results from an ultrasonic experiment conducted in a reinforced concrete specimen. The later coda waves of the envelope processed from the 60 KHz ultrasonic signal are individually used for intrinsic attenuation inversion whose distribution has similarity to the temperature distribution of the concrete block. Based on the inversion result of intrinsic attenuation, scattering strength is inverted from early coda waves separately, which successfully provides the structure of the small-scale heterogeneity in the material. The resolution test shows that we recover the distribution of heterogeneity reasonably well.
Exploring the potential of HAILCAST and LPI in km-resolution simulations over the Alpine-Adriatic region
Authors: Cui Ruoyi , Ban Nikolina , Demory Marie-Estelle , Schär Christoph
Published: March 2022

The Alpine and Adriatic regions are hotspots of frequent hail and lightning. Hail and lightning are associated with severe convective storms that happen under the large-scale forcing of surface fronts, upper-level fronts, convergence zones, or local thermal-topographic forcing. Convection-resolving models are run at the km-scale resolution, which improves the representation of topography. Moreover, they can explicitly resolve deep convection, thus reducing the uncertainties related to the use of deep convection parameterization in lower resolution models. Both aspects are beneficial for studying processes that drive severe convective storms over mountainous regions.

In this study, we analyze convection-resolving simulations of 8 heavy convective events performed with the COSMO-crCLIM model (GPU version of the Consortium for Small-scale Modeling) at 2.2 km horizontal grid spacing over the Alpine-Adriatic region. The cases are selected according to their impacts (size of hailstones, number of lightning strikes and damages), and the simulations are driven by the ERA5 reanalysis. For the simulation of hail and lightning, we use the one-dimensional hail growth model HAILCAST and the lightning potential index (LPI) implemented into the COSMO model, and compare results with observed hail properties and lightning flashes. In addition, we look into key variables for hail formation, including temperature, humidity, CAPE and CIN, and bulk wind shear. By performing a detailed analysis, we identify several environments that are favorable for strong convection and associated hail and lightning, such as a "loaded-gun" sounding, conditionally unstable layer and intrusion of dry air aloft. Evaluation of model simulations with available observations demonstrates overall very good performance of the model for the simulation of precipitation, hail and lightning. However, results depend upon the predictability of the cases, with lower predictability for deep convection events driven by local thermal-topographic forcing. 

Our findings indicate that HAILCAST and LPI can diagnose hail and lightning associated with severe weather events. Recently, we have started to assess changes in the occurrence and severity of such events with multi-seasonal simulations under current and future climate conditions using the pseudo-global warming (PGW) approach.
Quantification of local methane emissions over Middle East 
Authors: Liu Mengyao , van der A Ronald , Eskes Henk , Kang Hanqing , Veefkind Pepijn , Schneising Oliver , Ding Jieying
Published: March 2022

Methane (CH4) is the second most important greenhouse gas, of which more than 60 % CH4 is released through human activities. Satellite observations of CH4 provide an efficient way to analyze its variations and emissions. The TROPOspheric Monitoring Instrument (TROPOMI) onboard the Sentinel 5 Precursor (S5-P) satellite measures CH4 at a high horizontal resolution of 7 × 7 km2, showing the capability of identifying and quantifying the sources at a local to regional scale. The Middle East is one of the strong CH4 hotspot regions in the world. However, it is difficult to estimate the emissions here because several sources are located near the coast or in places with complex topography, where the satellite observations are often of reduced quality. We use the WMF-DOAS XCH4 v1.5 product, which has good spatial coverage over the ocean and mountains, to better estimate the emissions in the Middle East. 

The divergence method of Liu et al., (2021) has been proven to be a fast and efficient way to estimate CH4 emissions from satellite observations. We have improved our method by comparing the fluxes in different directions for better background corrections over areas with complicated topographies. The performance of the updated algorithm was tested by comparing the estimated emissions from a 1-month WRF-CMAQ model simulation with its known emission inventory over the Middle East. The CH4 emissions based on TROPOMI XCH4 are then derived on a 0.25 grid for 2019 and 2020. With the WMF-DOAS product, sources from oil/gas platforms over the Persian Gulf and sources on the west coast of Turkmenistan become clearly visible in the emission maps. Sources in the mountain areas of Iran are also identified by our updated divergence method. The locations of fossil fuel related NOX emissions usually overlap with CH4 emissions as can be seen in the CAMS bottom-up inventory. Therefore, we have compared our CH4 emission inventory with the emissions derived from TROPOMI observed NO2, in order to gain more insight into the source of the emissions, especially concerning the oil/gas industry in the region.
Evaluating atmospheric simulations of the Last Glacial Maximum using oxygen isotopes in ice cores and speleothems
Authors: Paul André , Tharammal Thejna , Cauquoin Alexandre , Werner Martin
Published: March 2022

Our goal is to investigate the structural uncertainty in the isotope-enabled atmospheric general circulation models iCAM5 and ECHAM6-wiso. In order to reduce all other sources of uncertainties, in particular, those that stem from different boundary conditions, we forced the two models by the same sets of pre-industrial (PI) and Last Glacial Maximum (LGM) surface boundary conditions; the latter were taken from GLOMAP  (Paul et al., 2021), which in turn were based on the MARGO project (MARGO Project Members, 2009) and recent estimates of LGM sea-ice extent. We compared our model results to reconstructions from ice cores (cf. Risi et al., 2010) and speleothems (cf. Comas-Bru et al., 2020). This comparison showed to what degree realizations of the atmospheric state of the LGM obtained from different models, due to different model set-ups and parameterizations, are in agreement with the proxy data. For example, the precipitation during the LGM was generally less depleted in the ECHAM6-wiso as compared to iCAM5, and as it turned out, the iCAM5 simulation produced only a rather weak LGM anomaly during summer (June-July-August, JJA) over the South Asian monsoon region.
Assessing Future Climate and Land Use Impacts to the Colorado River using a Bottom-up Modelling Approach Informed by Water Managers
Authors: Whitney Kristen , Vivoni Enrique , Wang Zhaocheng , Mascaro Giuseppe
Published: March 2022

Accelerated climate and land use land cover (LULC) changes are anticipated to have large impacts on water resources in the Colorado River Basin (CRB). Since land use is a result of complex socio-ecological factors, accurately predicting future patterns of LULC is challenging. In addition, substantial differences among a large number of climate models necessitate a screening process for impact and adaptation studies. As a result, limitations of conventional ‘top-down’ approaches are becoming increasingly apparent. More recently, ‘bottom-up’ assessments are gaining popularity for exploring climate and LULC conditions using a few selected cases that consider a range of possibilities. Here, we improved and employed the Variable Infiltration Capacity (VIC) model to generate streamflow projections across the CRB under multiple cases of climate and LULC changes. We integrated advances in the model using Landsat- and MODIS- based products to produce more realistic land surface conditions. Meteorological datasets were drawn from statistically downscaled projections (2006-2099) to represent ‘hot and dry’ and ‘warm and wet’ futures. Vegetation parameters were modified by using regional projections of a LULC model upon which more drastic disturbances were applied to forest cover types. Water managers in the CRB were consulted to ensure that a range of views were captured in the modeled storylines and to maximize the legitimacy and credibility of the research for decision-makers. Analyses were conducted to identify system vulnerabilities and unexpected outcomes that pose the greatest consequences to long-term water supplies in the CRB. Results indicated that forest disturbances partially offset warming effects to streamflow (basin-wide mean annual streamflow was up to 9% larger than the case without disturbance by end of century), allowing more neutral impacts under warming.
Lithospheric thermo-chemical heterogeneity and density structure of the Siberian craton
Authors: Shulgin Alexey , Artemieva Irina
Published: March 2022

We present a new model for the density structure of the lithospheric upper mantle beneath the Siberian craton, based on a 3D tesseroid gravity modeling. Our model is based on a detailed crustal structural database SibCrust (Cherepanova et al., 2013) constrained by regional seismic data. The residual lithospheric mantle gravity anomalies are derived by removing the 3D gravitational effect of the crust. We next convert these anomalies to lithosphere mantle in situ densities. To evaluate chemical heterogeneities of the lithospheric mantle, thermal effects are removed based on the global continental thermal model TC1 (Artemieva, 2006). The resulting density model at SPT conditions shows a highly heterogeneous structure of the cratonic lithospheric mantle. Density heterogeneities reflect a complex geodynamic evolution of the craton, which still preserves parts of the pristine cratonic lithosphere in areas where the lithosphere has not been modified by metasomatism associated with the Siberian LIP, several pulses of kimberlite-type magmatism, and rifting at the peripheral parts.
Seeing inside flood embankments: combining electrical and seismic imaging.
Authors: White Adrian , Chambers Jonathan , Wilkinson Paul , Wookey James , Kendall J. Michael , Dashwood Ben , Whiteley James , Boyd James , Watlet Arnaud , Morgan Dave , Ball John , Binley Andrew
Published: March 2022

Flood embankments (levees or dykes) are used worldwide to protect homes, industry and farmland from flooding caused by extreme weather events and tidal surges. Their role is becoming increasingly important for two key reasons: climate change is causing larger and more frequent floods, and the number of people living on floodplains is increasing globally. Both these factors necessitate that flood defences are well maintained to minimise failure during flood events, and reduce disruption, damage, and even loss of life.

 

There are more than 10,000 km of flood embankments in UK alone, so condition monitoring must be rapid. Current monitoring relies on qualitative walkover surveys every 6-12 months, but this can only detect the surface features that form in response to subsurface processes or characteristics. If we could detect subsurface properties and deterioration features directly it would enable us to identify areas at risk significantly earlier, minimising both risk and mitigation costs. Two complementary geophysical methods stand out: Electrical Resistivity Tomography (ERT) and Multi Channel Analysis of Surface Waves (MASW). These are sensitive to different hydro-mechanical properties of the materials that make up flood embankments and their foundations. ERT is sensitive to moisture content, clay content and porosity, whereas MASW is sensitive to elastic properties controlled by material strength, density, porosity and saturation.

 

In this work we combine co-located ERT and MASW surveys with time-lapse airborne lidar on three contrasting embankments on the River Thames, River South Tyne, and the Humber Estuary. Each site was selected based on known anomalies or the availability of existing geotechnical information to ground truth the geophysical measurements. The three embankments represent a range of different soil types, ages and varying foundation materials, making an ideal suite of targets to test the different geophysical methods.

 

In total c. 1 km of embankment was surveyed. Preliminary analysis shows good spatial agreement between units imaged by the ERT and those identified in the borehole data for each site. Areas of greatest settlement identified using time-lapse lidar also correlate with low resistivity anomalies indicating areas of soft clay and peat. Further data analysis will incorporate the MASW results and use clustering to quantitatively divide the subsurface into units with similar electrical and seismic properties. Geotechnical properties will then be attributed to each of the clusters, allowing more accurate fragility analysis of the embankment during flood conditions to be conducted.
Mixing contributions from resonant trapped internal waves generated by bottom topography in an estuary
Authors: Wegman Tess , Pietrzak Julie , Kranenburg Wouter , Labeur Robert Jan , Verlaan Martin
Published: March 2022

The Rotterdam Waterway is part of the Rhine-Meuse estuary, which is characterized a salt wedge estuary. Therefore, it is persistently strongly stratified. Field observations in the Rotterdam Waterway, described in earlier literature, reveal internal waves (IWs) generated by resonance over undular bottom topography. IWs are widely found in estuarine and coastal regions, and can contribute to mixing in stratified bodies of water. In this study we explore the generation of IWs over a series of sinusoidal bed forms and their potential of mixing.

An idealised 2D stretch of an estuary, containing sinusoidal bottom topography, is modelled in the non-hydrostatic finite element numerical model FINLAB. The effects of varying wavelength and wave height of the undular topographic features on internal wave generation and vertical mixing are evaluated.

From the model results we find that the generation of the resonant internal wave modes are in correspondence with an analytical analysis based on linear theory. Our results show that in the case of bed form induced internal waves, vertical mixing in the short 2D stretch increases, compared to a flat bed. This is predominantly caused by an increase in bottom friction. This suggests that the trapped internal waves only give a relatively small contribution to this increase in vertical mixing in the area of generation.

Further investigations are required to quantify the contribution from internal waves to vertical mixing, once the waves start to propagate through the domain. Furthermore, the model results will be compared to recent observations of internal waves in the Rotterdam Waterway. Internal wave characteristics and the generation mechanism will be compared to the model results.
Accounting for fish habitat fragmentation in global strategic assessments of future hydropower dam portfolios
Authors: Barbarossa Valerio , Schmitt Rafael
Published: March 2022

Dams contribute to water security, energy supply, and flood protection but also fragment habitats of freshwater fishes, limiting their dispersal ability and impairing fish movements to feeding and spawning grounds. This endangers freshwater biodiversity and the livelihoods and food security of people depending on freshwater fish.  Globally, only 37% of rivers longer than 1,000 km remain free-flowing. Habitat fragmentation levels for fish are highest in North America, Europe, India, and China. However, the expansion in hydropower capacity driven by national plans and energy transition scenarios will increase habitat fragmentation by 20-40 percentage points in fish diversity hotspots like the Amazon, Congo, and Mekong basins, with potentially detrimental consequences for fishes. Therefore, it is paramount to understand opportunities to reconcile needs for expanding renewable hydropower while preserving habitat for fish and associated benefits for humans. Using the Mekong as a case study, we prototype a tool to optimize tradeoffs between habitat fragmentation and energy benefits for basin-level dams’ portfolios based on global data sets. Such an approach can close an important gap in policy and trade-off analyses for hydropower which, because of lacking data, do not commonly include biotic impacts of dams as a metric. Based on a genetic algorithm, the approach allows identifying which dams to develop, remove, or upgrade with fish passages in order to reach the greatest benefits for future renewable energy systems with the least impact on fish populations.
The effect of loading rate on the mechanical behaviour and deformation mechanisms in reservoir sandstones
Authors: Jefferd Mark , Hangx Suzanne , Spiers Chris
Published: March 2022

The removal of pore fluids from sandstone reservoirs during hydrocarbon production, geothermal energy production, or when using geo-storage techniques may increase the effective overburden pressure on the host rock. The increased effective pressure may result in both elastic and inelastic strains being introduced into the reservoir host rock, which in turn may lead to surface subsidence and induced seismicity in the surrounding area. The elastic response of reservoir sandstone is, in general, well described by poro-elastic theory. However, much less is currently understood about the mechanisms controlling inelastic strain generation. While recent experimental results have concluded that clay-layer compaction in the grain boundaries can explain large portions of the recorded inelastic strain in the laboratory. Large uncertainties remain regarding if the inelastic deformation mechanisms operating at laboratory strain rates of 10-5s-1 are the same as those operating at typical reservoir strain rates of 10-12s-1.  

We present results from a series of triaxial deformation experiments carried out on Gronignen reservoir material, which were designed to assess how depletion (or loading) rate effects the partitioning between elastic and inelastic strain at pressure, temperature and fluid conditions representative of the Groningen reservoir. We demonstrate that a non-negligible rate-effect is observed, and that the total amount of inelastic strain introduced into the samples may be twice as high in experiments carried out at an axial strain rate of 10-9s-1 compared to experiments carried out at a strain rate of 10-5s-1. We conclude that both rate-dependent frictional sliding and subcritical cracking may be responsible for the observed rate-dependence in inelastic strain generation. We also introduce the early workings of a study into how time-dependent sandstone deformation may play a role in increasing the total amount of inelastic strain observed during the cyclic loading and unloading of sandstones.
Structural Geologic Modelling and Restoration Using the Ensemble Kalman Filter
Authors: Oakley David , Cardozo Nestor , Røe Per , Almendral Vazquez Ariel
Published: March 2022

Structural restoration using kinematic principles of fault-related folding is a valuable tool in building realistic geological models. Models are, however, typically uncertain and non-unique. While data inversion methods can be employed to find a best-fit model and estimate uncertainty, their use is limited to relatively simple models involving a single fault in two dimensions. In this work, we employ an iterative form of the Ensemble Kalman Filter (EnKF) together with a kinematic model for deformation around normal faults to build and restore three-dimensional structural geologic models. The EnKF is ideally suited to data inversion problems that involve large numbers of model parameters and is frequently used in reservoir simulations, which often do not consider uncertainty in geologic structure. We develop a workflow in which fault geometry, the distribution of slip on a fault, and the geometry of folded horizons are all modelled using the EnKF. The models are constrained by observations of faults and horizons in the present deformed state together with the expectation that horizons should restore flat. We test two modelling approaches: a restoration-based approach in which the model is built in the deformed state and then restored, and a forward modelling-based approach in which the model is built in the restored state and then forward modelled to match present-day data. We test these methods first on a synthetic model involving a single fault and then on a real-world example involving five faults. Both the restoration- and forward modelling-based methods work well for the synthetic model, but forward modelling works best for the more complex real-world case study. The EnKF method provides not only a best-fit model but also an estimate of model uncertainty. The estimation of uncertainty is, however, hindered by the phenomenon of ensemble collapse, which results in underestimation of the uncertainty in model parameters at small ensemble sizes. We employ bootstrap-based localization and covariance inflation to help mitigate this issue and use a dummy parameter to identify whether significant ensemble collapse has occurred. While ensemble collapse remains a challenge in some cases, the EnKF nonetheless shows considerable promise as a tool for building complex many-parameter structural models that are kinematically restorable, and it holds the potential for future integration of structural modelling with other EnKF-based workflows in subsurface modelling.
Using local moisture recycling to assess the impact of regreening on the local water cycle in five Mediterranean regions
Authors: Theeuwen Jolanda , Staal Arie , Hamelers Bert , Soltani Mohsen , Tuinenburg Obbe , Dekker Stefan
Published: March 2022

Mediterranean regions worldwide are expected to face an increase in water scarcity due to land degradation and climate change. Regreening enhances infiltration and preserves evapotranspiration, which may enhance rainfall locally and thus potentially reduce water scarcity. However, the exact impact of such land cover changes on the hydrological cycle remains unclear. To assess the impact of regreening on the local water cycle, we aimed to identify drivers of the local moisture recycling ratio (LMR) for five Mediterranean regions: southwestern Australia, California, central Chile, the Mediterranean Basin, and the Cape region of South Africa. We defined LMR as the fraction of evaporated moisture that rains out within approximately 50 km from its source and we calculated it using the output of a Lagrangian atmospheric moisture tracking model. For this, we studied the correlation between LMR and ecohydrological variables (dependent on the hydrological cycle or vegetation, i.e., precipitation, evaporation, aridity and vegetation cover) and non-ecohydrological variables (i.e., wind, orography and distance to the nearest coast) using Spearman rank correlation and principal component analyses. We find first, on average, LMR is small (1-2%) but varies among and within the five regions. Second, precipitation corresponds strongest to LMR in all five regions. Third, regreening could enhance LMR and strengthen the local water cycle for all five Mediterranean regions, although to different extents. The results suggest that an increase in evaporation due to regreening positively affects LMR and thus strengthens the local water cycle. The enhanced local water cycle reduces aridity, which induces LMR, and thus a positive feedback might be established. Finally, the correlation between LMR and ecohydrological and non-ecohydrological variables varies among the five regions. Therefore, the variables influencing LMR most are different for each region. Our results suggest that the potential impact of regreening varies among the Mediterranean regions due to the difference in correlations between LMR and the non-ecohydrological variables. Our study helps understand where regreening might benefit the local water cycle in regions with a Mediterranean climate.
Skillful Prediction of Decadal Sea Ice Variability in the Antarctic Seas
Authors: Morioka Yushi , Iovino Doroteaciro , Cipollone Andrea , Masina Simona , Behera Swadhin
Published: March 2022

This study examines the prediction skill of decadal sea ice variability in the Antarctic Seas using a coupled general circulation model (SINTEX-F2) developed under the EU-Japan collaboration. A decadal reforecast experiment with both sea surface temperature (SST) and sea ice concentration (SIC) initializations shows higher prediction skills of the SIC in the Weddell Sea during austral autumn compared to an experiment with SST initialization only. The former experiment reproduces decadal SIC increase after the late 2000s, which is associated with anomalous sea ice advection by the strengthened Weddell Gyre. A third experiment with the SST, SIC, and subsurface ocean temperature/salinity initializations shows the highest prediction skills of the SIC in the Ross, Amundsen, and Bellingshausen (RAB) Seas during austral winter and spring. The model captures decadal SIC increase after the late 2000s when a larger number of subsurface ocean observations by Argo floats become available. The decadal SIC increase is found to be linked with anomalous cooling of subsurface ocean by the strengthened Antarctic Circumpolar Current and the associated downwelling anomalies in the RAB Seas. These results indicate that both ocean and sea ice initializations benefit skillful prediction of decadal variability in the Antarctic sea ice.
Diffraction imaging of alpine glacier GPR data
Authors: Klahold Johanna , Schwarz Benjamin , Bauer Alexander , Irving James
Published: March 2022

Over the past decades, ground-penetrating radar (GPR) has become a fundamental tool in glaciological studies thanks to its tremendous capacity to provide high-resolution images in snow and ice. 3D acquisitions in particular can give detailed information on the internal structure, properties, and dynamics of glaciers. For imaging and highlighting important englacial and subglacial features such as meltwater tunnels and voids, an analysis of the spatial distribution of diffractions in the data holds great potential. However, the diffracted wavefield typically has low amplitude and is often masked by more prominent arrivals. Diffraction separation and imaging procedures have already become topics of significant interest in the field of exploration seismology, and may potentially open new possibilities for the analysis of glacier GPR data.

Here, we explore the potential of recent advances in diffraction imaging for the analysis of alpine glacier GPR data. To this end, we consider a 3D data set acquired on the Haut Glacier d’Arolla (Valais, Switzerland) using a 70-MHz single-antenna real-time-sampling GPR system. The approach we use coherently approximates the dominant reflected wavefield and subtracts it from the data. The remaining diffracted wavefield is then enhanced using local coherent stacking. We find that this methodology is highly effective at isolating diffractions in glacier GPR data and provides clean images of the diffracting structures. Current work includes investigation of the correlation between these structures and the englacial and subglacial hydrological network.
Soil structure changes of engineered soils in bioretention cell
Authors: Heckova Petra , Snehota Michal , Koestel John , Klement Ales , Kodesova Radka
Published: March 2022

Engineered soils play an important role in urban hydrology e.g. in the functioning of green roofs and stormwater bioretention cells. Water infiltration, colloid transport, and heat transport are affected by changes in pore system geometry particularly due to the development of macropores and clogging by particles. The rate of pedogenesis is often faster than in natural soils due to higher loads of particles as well as by extreme water regimes. In the presented research we assess the temporal changes of soil structure of engineered soils in typical bioretention beds by conducting field scale and laboratory experiments. The aim is to elucidate changes in bioretention cell performance by studying the structural changes of soils at the microscale by invasive and noninvasive methods. Noninvasive visualization methods such as computed microtomography (CT), are an effective mean of soil structure assessment. X-ray CT is capable to investigate soil in terms of structure development, pore-clogging and pore geometry deformations.

Two identical bioretention cells were established in December 2017. The first bioretention cell (BC1) collects the stormwater from the roof of the nearby experimental building (roof area 38 m2). The second bioretention cell BC2 is supplied from a tank using a controlled pump system for simulating artificial rainfall. Each BC is 2.4 m wide and 4.0 m long. The 30 cm thick biofilter soil mixture is composed of 50% sand, 30% compost, and 20% topsoil. Bioretention cells are isolated from the surrounding soil by a waterproof membrane. The regular soil sampling program was initiated in 2018 in order to visualize and quantify the soil structure and internal pore geometry of samples. Undistributed samples were collected from the surface of the filter layer twice a year from each BC. The aluminum sampling cylinders had an internal diameter and height of 29 mm. Three batches of samples were taken during three years. The first set of 24 undisturbed samples was collected upon planting in June 2018, while the second set of 24 samples was taken after the end of the first vegetation period in November 2018. The second and third batches, each of 48 samples, were taken in 2019 and 2020 in the same period as in the first year.  Those collected samples were scanned by (CT) imaging.

The analysis performed by SoilJ package shows the initial decrease of macroporosity during the first season as a result of soil consolidation and subsequent further development of the soil's pore system.
Modelling the effects of Climate Change and Deforestation on Fire Risk in Tropical Borneo  
Authors: Davies-Barnard Taraka , Catto Jennifer , Harper Anna
Published: March 2022

Fire in the peatlands and forests of Borneo is a significant environmental issue, with far reaching social and climatic consequences. The KaLi project aims to better understand fire risk in the Kalimantan region of Indonesia, and this part of the project focusses on the climatic risk. While fire severity and frequency are generally expected to increase with climate change, the unique climate and geography of Indonesia and the island of Borneo create heterogenous patterns of change. We ran simulations of RCP8.5 with and without deforestation using regional climate model RegCM4 with boundary conditions from a range of CMIP5 model simulations. These simulations provide high-resolution climate simulations that show the relative contribution of climate change and deforestation to the climatic risk of fire using the Fire Weather Index.

We find that climate and fire risk from climate are significantly affected by both climate change and deforestation, though not to the same extent. The surface temperature in the multi-model mean RCP8.5 simulation increases by ~4 degrees, and deforestation further increases the temperature by ~2 degrees. The climate effects of both RCP8.5 and deforestation are affected by the altitude. Precipitation, in particular, is higher above 500m in the deforestation scenario. Both deforestation and RCP8.5 increase the fire risk according to the Fire Weather Index. Deforestation causes a smaller increase than RCP8.5, but is locally controllable in a way that the carbon emissions causing climate change are not. These high-resolution simulations provide a guide to the most vulnerable areas of Borneo from climatic increases in fire risk, and complement efforts to understand the social aspects of fire risk that are a part of the KaLi project.
SOC indicator of land-degradation: responses of continuous and non-standard discrete RothC  models to environmental changes  
Authors: Marangi Carmela , Diele Fasma , Luiso Ilenia , Martiradonna Angela , Wozniak Edyta
Published: March 2022

The effects of environmental change on ecosystem dynamics is nowadays a major research question. Soil organic carbon (SOC) models are integrated into many ecosystem models for projecting the effects of these changes in the achievement of land degradation neutrality. The  Rothamsted Carbon (RothC) model, initially developed to simulate the effects of different practices for long-term agricultural experimental sites, can be successfully used to monitor and project the SOC indicator of land degradation. Here, continuous and discrete versions of the RothC model are firstly compared on classical long-term experiments carried out at the Rothamsted Experimental Station; then a non-standard monthly time stepping procedure is used to evaluate the response of the model to changes of temperature, Net Primary Production (NPP), and land use soil class (forest, grassland, arable)  in the protected areas of Alta Murgia National Park in the Italian Apulia region and Magura National Park in Polish Subcarpathian Voivodeship.  
Exploring the Bacterial Preference for Terrestrial or Marine Organic Matter in Estuarine Sediments Using Compound Specific Stable Carbon Isotope Ratios: A Degradation Kinetics Study 
Authors: Mirzaei Yeganeh , Gelinas Yves
Published: March 2022

Preserving the health of estuarine ecosystems has been an increasing challenge in the recent past with the spreading of areas affected by deep-water hypoxic conditions. Hence, it is of critical importance to identify the causes of such perturbation, triggered by changing ocean circulation and increasing inputs of organic matter (OM), which results in serious threats to living species. Estuaries are large deposition centers for organic matter (OM) where stable carbon isotope ratios of either bulk OM or specific organic compounds provide detailed information about carbon cycling and the tracing of OM sources and transformations along the terrestrial-marine continuum. In particular, the ∂13C values of biomarkers that are specific to heterotrophic bacteria (branched iso- and anteiso-C15:0 fatty acids) can be used to assess the type of OM that they preferentially degrade as the ∂13C values of marine organic carbon (OC) are more enriched in 13C than those of terrestrial OC. However, very little is known on the dynamics between the seasonally varying relative inputs of terrestrial vs. marine OM and the ∂13C values of these bacteria-specific fatty acids. In this study, we will use a kinetic batch incubation approach in which natural sediments from the St. Lawrence Estuary and Gulf, amended with fresh terrestrial or marine OM characterized by a very different 13C/12C ratio (difference of between 10 and 14 ‰ depending on the sampling station), will be incubated for varying amounts of time. Quenching of the incubations followed by the extraction, quantification and isotopic characterization of the bacterial fatty acids will allow determining the rate and temporal extent of change of their compound-specific ∂13C values. Bulk elemental (OC and total nitrogen) and isotopic (∂13C and ∂15N) mass balances will be precisely monitored throughout the experiment. Acquisition of this knowledge, combined with results from other studies carried out in our lab, will provide a better understanding of the relative importance of terrestrial and marine OM processing in the onset of hypoxia and will be exploited as a guide for remedial efforts aiming to improve the health of such an important ecosystem.