bluuebunny/crossref_metadata_2025 huggingface dataset:
Hybrid full-wave inversion based on a B-spline level set mesh deformation method of borehole seismic data for a subsalt imaging context
Authors: Khazraj Kaoutar , Barnes Christophe , Maillot Bertrand
Published: February 2023

Oil and gas industry is particularly interested in subsalt imaging because salt bodies often serve as seals for hydrocarbon reservoirs especially on the flanks and underneath the salt body. Classical imaging or full-wave inversion have encountered many difficulties in imaging such subsalt regions. The high velocity contrast between the salt body and its surroundings, the shape of the salt body, and the strong attenuation of waves propagating in the salt make accurate imaging difficult.Imaging from surface seismic data has already been addressed. We propose to apply the full-wave inversion approach to borehole seismic data.  These data are supposed to provide more informative seismic signals (one-way, transmitted waves, scattered field near receivers, …) and should better constrain the salt flanks and bottom imaging. Unfortunately, this inverse problem is severely ill-posed due to the lack of data redundancy.  Introducing geological prior information through the parameterization of the salt geometry using the level set method partly overcomes this problem. This approach implicitly defines the salt/sediments interface through a smooth function. This hybrid  full-wave inverse problem combines the classical field gradient and the level set geometric gradient, allowing us to retrieve respectively the physical parameters and the salt body geometry.The forward wave equation for a heterogeneous elastic domain is solved using the spectral element method. This method allows us to have a better representation of the salt/sediments interface, thus a more accurate modeling of the scattered wavefield due to interactions at the interface. Regarding the level set inversion, we define the implicit function in a parametric framework. We use compactly supported B-spline basis functions for their ability to represent a wide range of geometries compared to radial basis functions, for instance.During the level set inversion process, when the salt/sediments interface evolves, updating the physical model parameters near the interface becomes an issue. We propose to perform a continuous deformation of the medium while conserving the mesh topology. The interface nodes are moved consistently with the implicit level set function. Furthermore, this approach  preserves a meshed representation of the interface through the inversion process allowing a more accurate seismic modeling. The mesh deformation is obtained by geostatistical kriging of node locations, constrained by the updated interface position.In short, we propose a hybrid full-wave inversion method to estimate both material parameter fields and geometric parameters of the salt/sediments interface. The method is validated on several elastic models using synthetic seismic well data in a subsalt imaging context.
Azimuthal Anisotropy in the Eastern Alpine Crust from Ambient Noise Tomography
Authors: Kästle Emanuel D. ,   AlpArray Working Group
Published: February 2023

Making use of the dense AlpArray and SwathD networks in the eastern Alps, a large dataset of Rayleigh phase-velocity measurements is extracted. This dataset is the basis for a 3D azimuthally anisotropic shear-velocity model of the Alpine crust. A 2-step inversion approach is followed: First, phase-velocity maps are created which are inverted for the shear velocity structure at depth in a second step. In both steps, a Bayesian (rjMcMC) approach is used to find the posterior distribution of anisotropic models. The model uncertainties are propagated from the phase-velocity maps to the depth inversion to make sure that the data is not overfitted. The final model shows a 2 layer anisotropy in the Alpine crust, the upper crustal layer is mostly orogen parallel and follows the major fault structures. The lower crustal to uppermost mantle layer shows orogen-perpendicular fast axis in the Alps and an anisotropy following the curvature of the Alps in the northern foreland. The importance of microfabric such as microcracks and oriented mineral grains is difficult to estimate from the presented model on the effective regional-scale anisotropy. But the results suggest that the azimuthal anisotropy may be largely controlled by macro-scale structures. The transition from upper to lower crustal anistotropy takes place at approx. 20 km depth which is unlikely to be due to the brittle-ductile transition. But it could indicate that upper and lower crust are only weakly coupled underneath the Alps.
Post-Processing of CMAQ forecast for Improving Air Quality Predictions
Authors: Alessandrini Stefano
Published: February 2023

We will show some preliminary results of our NOAA Joint Technology Transfer Initiative (JTTI) 2-year project with the goal of applying a machine learning (ML) post-processing to improve the Community Multi-scale Air Quality (CMAQ) model operational air quality forecasts issued over the US by National Air Quality Forecasting Capability (NAQFC) at NOAA/NCEP. Specifically, we have tested an extension of the analog ensemble (AnEn) model currently implemented at the NAQFC from point-based to 2D gridded predictions.The AnEn utilizes a training dataset comprising predictions from CMAQ and corresponding observations of the quantity to be predicted (i.e., O3 or PM2.5) to generate future ensemble predictions based on past observations. The ensemble is constructed for a given deterministic CMAQ forecast by collecting past observations corresponding to the best matching past CMAQ forecasts (called analogs) to the current CMAQ prediction.We have conducted a preliminary application of the AnEn to reduce the errors of CMAQ PM2.5 and ozone surface gridded concentrations using a combination of past gridded chemical reanalysis from the Copernicus Atmosphere Monitoring Service (CAMS) Near-Real-Time model with measurements from AirNow stations. The analog method requires a continuous training dataset of hourly values of observed chemical concentrations obtained by merging the CAMS surface PM2.5 and ozone fields with the respective observations from the AirNow network using the Satellite-Enhanced Data Interpolation technique (SEDI) (Dinku et al. 2015). SEDI removes the bias from CAMS analysis and short-term forecast fields while preserving the AirNow-measured values at the station locations.We will first show validation of the SEDI bias-corrected CAMS concentrations against AirNow PM2.5 and ozone-measured concentrations from stations not used in the SEDI correction process. Then, we will verify the performance of the whole forecasting system in some regions of the contiguous United States in the 0-72 hours lead time range. 
First ground-deployment of a new small-footprintcavity-ring-down spectrometer for NO3 and N2O5 in a temperate forest during the ACROSS campaign
Authors: Türk Gunther N. T. E. , Andersen Simone T. , Dewald Patrick , Schuladen Jan , Seubert Tobias , Crowley John N.
Published: February 2023

At nighttime, when concentrations of the OH-radical are low, the nitrate radical, NO3, over takes the role of major initiator of the oxidation of many organic trace gases, especially those containing one or more double bonds. In contrast to daytime, where the lifetime of NO3 is very short due to its photolysis and reaction with NO, NO3 can reach mixing ratios of several tens of ppt at night. NO3 can also react with NO2 to form N2O5. As N2O5 is thermally stable, the three trace-gases usually exist in equilibrium:NO3 + NO2 + M                ⇌ N2O5 + MMeasurements of NO3 and N2O5 are central to our understanding of the fate of NOx at night. Loss of NO3 to gas-phase reactions (forming e.g. organic nitrates) has a different impact on NOx than formation of N2O5 which may hydrolyse on aerosol to form particulate nitrate.During the ACROSS campaign in Rambouillet Forest (France), a recently built two-channel cavity-ring-down spectrometer was deployed for the first time to record mixing ratios of NO3 and N2O5 at night over a period of several weeks. NO3 was detected directly at 662nm in one channel while N2O5 was first converted to NO3 in a thermal dissociation inlet before being detected in the same way.In this work, we describe the new instrument in detail and compare obtained data with those measured by an established cavity-ring-down instrument. We show that, at a sampling height of about 6m, NO3 and N2O5 mixing ratios were low and frequently below the detection limit of both instruments; the likely reasons for this are discussed.
A new theoretical framework to model radial transport of energetic particles by ULF waves in the Earth's magnetosphere.
Authors: Osmane Adnane
Published: February 2023

Radial diffusion in planetary radiation belts is a dominant transport mechanism resulting in the energisation and loss processes of charged particles by ultra-low frequency (ULF) fluctuations in the Pc4-Pc5 range. The theoretical framework upon which radial diffusion coefficients have been analytically derived in the past 60 years belongs to various types of quasi-linear theories. In quasi-linear theories, the evolution equation for the distribution function experiencing radial diffusion is only valid on slow timescales longer than the characteristic period of the ULF waves and the azimuthal drift period of the particles, ranging from tens of minutes to a few hours for electrons with energies between tens of keV to several hundreds of keV. Therefore, radiation belts’ dynamical processes occurring on fast timescales comparable to ULF wave periods or azimuthal drift periods, such as fast magnetopause losses localised in magnetic local time (MLT), cannot self-consistently be quantified in terms of radial diffusion models. In this communication, we present a new theoretical framework based on drift kinetic (Hazeltine, 1973) to distinguish between the fast and slow response of energetic electrons to ULF waves. We conclude our talk with two examples to demonstrate the benefits of the drift kinetics approach: 1) fast electron losses due to MLT localised compression of the magnetopause, and 2) non-diffusive acceleration associated with symmetric ULF fluctuation.  
Statistical modeling of the flood hazard in a complex and non-stationary hydrological system: case study on the Niger River in Niamey
Authors: Sauzedde Elisa , Vischel Théo , Panthou Geremy , Tarchiani Vieri , Massazza Giovanni
Published: February 2023

Droughts are a recurring long-term problem in West Africa, but in recent years the region has also experienced a significant increase in damaging floods. Increasing trends in extreme discharges have been shown, reflected by an increase in return level magnitude since 1980s in Sahelian rivers. Our study targets flood prediction within the regional catchment of the Niger River at Niamey, the capital of Niger. The river hydrograph has changed significantly since the drought between the 1970s and 1980s, evolving from a single peak to a two-hump hydrograph: a first flood, coming mainly from three direct Sahelian tributaries of the right bank of the Niger River, and a second one, coming from the more remote Guinean basin. Predicting floods in Niamey is not straightforward because of the complexity of the hydrological system, which combines non-stationarity and the difficulty of deconvoluting the two floods and separate their own trends.The objective of the study is to quantitatively assess the hydrological hazard on the Niger River at Niamey based on a flow data set covering the period 1950-2020 by developing a statistical modeling approach that allows to integrate both the hydrological complexity and the non-stationarity of floods. An important question addressed by the proposed approach is to evaluate the contribution of considering hydrological complexity in non-stationary statistical modeling. This is achieved by defining several flood samples and proposing different non-stationary models adapted to their complexity.
Reconciling conflicting evidence for the cause of the observed early 21st century Eurasian Cooling
Authors: Sobolowski Stefan , Outten Stephen , Li Camille
Published: February 2023

Arctic amplification of global warming is accompanied by a dramatic decline in sea ice. This, in turn, has been linked to cooling over the Eurasian subcontinent over recent decades, most dramatically during the period 1998-2012. Such a coherent and pronounced cooling is a counterintuitive impact under global warming. Some studies have proposed a causal teleconnection from Arctic sea ice retreat to Eurasian wintertime cooling; others argue that Eurasian cooling is mainly driven by internal variability. Overall, there is an impression of strong disagreement between those holding the “ice-driven” versus “internal variability” viewpoints. We offer an alternative framing that shows that the sea ice and internal variability views can be compatible. Key to this is viewing Eurasian cooling through the dual lens of dynamics (linked primarily to internal variability with a small contribution from sea ice; cools Eurasia) and thermodynamics (linked to sea ice retreat; warms Eurasia). This framing, combined with recognition that there is uncertainty in the hypothesized mechanisms themselves, allows both viewpoints (and others) to co-exist and contribute to our understanding of Eurasian cooling. A simple autoregressive model shows that strong Eurasian cooling is consistent with internal variability, with some periods being more susceptible to strong cooling than others. Rather than posit a “yes-or-no” causal relationship between sea ice and Eurasian cooling, a more constructive way forward is to consider whether the cooling trend was more likely given the observed sea ice loss, as well as other sources of low-frequency variability. Taken in this way both sea ice and internal variability are factors that affect the likelihood of strong regional cooling in the presence of ongoing global warming. Improving our understanding of the underlying mechanisms is critical for quantifying regional responses and impacts as well as producing reliable near-term climate predictions. 
Variability and vertical structure of gaseous air quality indicators above urban areas: IAGOS in-situ profiling of nitrogen oxides, ozone, and carbon monoxide
Authors: Mahnke Christoph , Bundke Ulrich , Houben Norbert , Blomel Torben , Nédélec Philippe , Thouret Valérie , Clark Hannah , Petzold Andreas
Published: February 2023

Nitrogen oxides (NOX), ozone (O3), and carbon monoxide (CO) are important air quality indicators which have anthropogenic and natural sources at ground (e.g.: transport emissions, industry, agriculture, biomass burning) and within the troposphere (e.g.: lighting, aircraft emissions). Furthermore, their concentrations in the atmosphere are strongly affected by photochemistry. The European Research Infrastructure IAGOS (www.iagos.org) is using in-service passenger aircraft as observation platforms, equipped with instrumentation for measuring gaseous species, aerosols, and cloud particles. IAGOS monitors the vertical profiles of climate and air quality relevant trace gases like CO, O3, NO, NO2 and NOX near airports of highly populated urban areas (e.g.: Frankfurt (Main) and Paris) during take-off and landing. These profiles provide essential information about the chemical composition of the lower troposphere, which is not available from surface-based stations or remote sensing instrumentation.Here, we characterize the variability and the vertical structure of these trace gases in the background atmosphere in the lower free troposphere that interacts with the urban boundary layer. In addition, layers of enhanced pollution level can be detected that were advected from distant source regions and have the potential to affect the urban air quality at the receptor site due to downmixing. This data provides valuable information that is complementary to the surface-based air quality network stations, facilitating the link to high-resolution models and satellite observations, where IAGOS can provide information about e.g., the vertical profile of the NO to NO2 ratio. The latter being difficult to retrieve from remote sensing measurements.Acknowledgments: This work is part of the RI-URBANS project and has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 101036245. We thank all airlines contributing to IAGOS, in particular Deutsche Lufthansa and Lufthansa Technik for enabling the observations. The German Federal Ministry of Education and Research (BMBF) is acknowledged for financing the instruments operation and data analysis as part of the joint project IAGOS-D under grant 01LK1301A.
H2O-fluxed melting buffers crustal temperatures and stabilizes magmatic mushes
Authors: Annen Catherine , Weinberg Roberto
Published: February 2023

Many conceptual models in igneous petrology and volcanology involve the protracted presence of large volumes of magmatic mushes in the crust. We used 1D numerical simulation to explore how the inflow of aqueous fluids into a section of crust facilitates melting and stabilizes columns of mush.Inflow of H2O into a crustal section whose temperatures are above the water-saturated solidus results in the following chain of processes: it induces melting; melting consumes latent heat; latent heat consumption lowers temperatures; reduced temperatures cause an increase in heat flow into the melting region. In detail, the behaviour of the upward migration of the water-fluxed melting front depends on the relative ratios between heat and H2O diffusivities.  The upwards flow of H2O is accompanied by melting until the H2O front reaches the water-saturated solidus isotherm.  If the transfer of H2O through chemical diffusion enhanced by advection (effective diffusivity) is slower than the transfer of heat, the melting front progress smoothly upwards. If the transfer of H2O, aided by advection, is faster than the transfer of heat, then the depth of the melting front oscillates up and down, resulting in parts of the crust going through more than one episode of melting.Our results show that H2O-fluxed melting of an haplogranite crust produces columns of mush that are more vertically extensive and more long-lived than dehydration melting of a biotite-gneiss, with the amount of melt depending on both the quantity of H2O in the system and how fast it diffuses relative to heat. Thus, the net effect of the inflow of H2O into a hot crust is to cause cooling and lowering of the heat flow through the crust to the surface while increasing the heat content stored in the crust, in the form of a low-temperature mush column.
DC and FDEM salt wedge monitoring of the Po di Goro river (Italy).
Authors: Rizzo Enzo , Boldrin Paola , Bondesan Alessandro , Droghetti Francesco , Capozzoli Luigi , De MArtino Gregory , Ferrari Enrico , Fornasari Giacomo , Giampaolo Valeria , Neri Federica
Published: February 2023

The global warming is affecting the rising seas, which increase the saltwater contamination of the coastal zone in terms of intrusion and penetration in the delta system. The delta systems are characterized by complex dynamic between freshwater coming from continent and saltwater. The hydrodynamic system is greatly affected by the problem of climate change producing a scarce recharge of the aquifers and an increase of the upstream of the mixing zone in the surface waters. These conditions can hinder the water use for irrigation purpose leading to salinization of soils. This summer the Po River underwent a large saltwater intrusion crisis endangering the sustainability of the freshwater resources. The saline wedge in the Po Delta area defined salinisation of groundwater and the soil. These phenomena allow for the active ingression of seawater from the east because the hydraulic head is not sufficient to avoid water to flow inland from the sea. In order to define the water quality, the electrical conductivity (EC) is one of the typical used chemical-physical parameters. However, a common probe defines a punctual acquisition and, therefore, it is time consuming to make a monitor along a long river (> 50km), such as the Po di Goro, that is one of the Po River branches. The research group defined two fast geophysical approach for the monitoring of the saltwater penetration and intrusion. The FDEM method was used to detect the saline wedge in the river and the Electrical Resistivity Tomography was applied to monitor the hydrodynamic iteration between the river and the subsoil around the riverbanks. Two geophysical field activities were planned before and after the salt penetration crisis in the Po River, defined in the last summer. In detail, two ERTs and two long FDEM profiles were carried out along the Po di Goro river. Moreover, a “moving boat” approach with a multilevel EC probe was applied to join the acquired geophysical data set. The ERT sections highlighted how the salty water in the river contaminated the surrounding subsoil. The FDEM data sets defined the hydrodynamic of the saltwater wedge in the river detecting the salty plume front. These results highlight the great potential of the proposed geophysical approach to monitor the saline plume during crisis periods.
On the Pacific Decadal Oscillation Simulations in CMIP6 Models: A New Test‐Bed from Climate Network Analysis
Authors: Ma Yiling
Published: February 2023

As a dominant pattern of the North Pacific sea surface temperature decadal variability, the Pacific Decadal Oscillation (PDO) has remarkable influences on the marine and terrestrial ecosystems. However, the PDO is highly unpredictable. Here, we assess the performance of the Coupled Model Intercomparison Project Phase 6 (CMIP6) models in simulating the PDO, with an emphasis on the evaluation of CMIP6 models in reproducing a recently detected early warning signal based on climate network analysis for the PDO regime shift. Results show that the skill of CMIP6 historical simulations remains at a low level, with a skill limited in reproducing PDO’s spatial pattern and nearly no skill in reproducing the PDO index. However, if the warning signal for the PDO regime shift by climate network analysis is considered as a test-bed, we find that even in historical simulations, a few models can represent the corresponding relationship between the warning signal and the PDO regime shift, regardless of the chronological accuracy. By further conducting initialization, the performance of the model simulations is improved according to the evaluation of the hindcasts from two ensemble members of the Decadal Climate Prediction Project (NorCPM1 and BCC-CSM2-MR). Particularly, we find that the NorCPM1 model can capture the early warning signals for the late-1970s and late-1990s regime shifts 5–7 years in advance, indicating that the early warning sig- nal somewhat can be captured by some CMIP6 models. A further investigation on the underlying mechanisms of the early warning signal would be crucial for the improvement of model simulations in the North Pacific.
The distributions of precipitations have been changing across the Mediterranean region in the last 70 years… but not always as we expect !
Authors: André Julie
Published: February 2023

Climate change is known to have consequences on both mean and extreme precipitations, with potentially threatening impacts on societies. The Mediterranean region is particularly affected, being a hotspot of temperature and precipitation changes: this region is expected to get much drier, but with more extreme rainfalls. Though the two extremes of precipitations (absence of rain -drought, dry spells etc. - and very heavy rainfalls) are crucial and well-studied, the evolution of the rest of the rain distribution has been quite overlooked in the literature. Still its study might help to get a broader and more coherent picture of the evolution over the last decades. In the Mediterranean, we commonly expect a “water cycle paradox”, i.e. decreasing mean annual precipitation (“drying”) while very heavy rainfalls intensify.In this presentation, we look at how the whole wet-days precipitation distribution changes, in the Mediterranean region over the recent past. We use reanalysis data (ERA5) covering the whole 1950-2021 period at daily timescale. We study the trends of the rain percentiles and their statistical significance over the last 70 years.
We see indeed sub-regions where the “water cycle paradox” is happening, such as the Iberia peninsula as a whole or more specifically Andalusia. For those, the quantile trend curve is in a “U-shape”, with decreasing rain quantiles up to a given threshold (“inversion quantile”) and then an increasing distribution tail. This “inversion quantile” can vary a lot from one place to another.

However we also find that the “U-shape” trend behavior is not the norm for the Mediterranean region: the situation is more complex. In fact, two additional behaviors are observed according to the location: some regions where the whole rain distribution decreases, and others where it all increases (which is a behavior more expected in Northern Europe or over the oceans). We give a map of the “U-shape” regions and of those two supplementary behaviors, and test its robustness.

By modeling the rainy days distribution with a simple Weibull law (2-parameters), we manage to get an analytical criterion for the type of rainfall percentiles trend behavior. This Weibull model also enables us, for regions having the “U-shape” behavior, to derive an analytical expression for the “inversion quantile”.
From salt-detached gravity-driven extension of a rifted margin to its inversion: The Cotiella Massif case study (Southern Pyrenees)
Authors: Estiarte-Ruiz Mercè , Santolaria Pablo , Ferrer Oriol , Muñoz Josep Anton , Roca Eduard , Snidero Marco
Published: February 2023

The Cotiella Massif is included in the Cotiella-Bóixols thrust-sheet, one of the three imbricated thrust sheets of the South-Pyrenean thrust system. It originated from the inversion of the Cotiella Basin, a post-rift gravity-driven salt-bearing assemblage of isolated sub-basins. On them, upper Albian to lower Coniacian post-rift carbonate platforms collapsed above Upper Triassic evaporites (Keuper facies), and middle Coniacian to lower Santonian minibasins developed during the margin failure due to salt evacuation and gravity-driven extension. Seismic scale rollovers developed in the hanging wall of basinward-dipping listric faults isolating four sub-basins: Cotiella, Armeña, Peña del Mediodia, and Seira. Additionally, structural and sedimentological evidence suggests passive diapirism at the footwall of these faults. Upon the Pyrenean orogeny, diapirs were rejuvenated, squeezed and welded, faults were positively inverted, and the salt-detached gravity system was incorporated into the orogen.In this work, we present a detailed geological map of the Cotiella Basin around the Reduno downward-facing anticline which represents the basinward northern edge of the Cotiella sub-basin and its contact with the Armeña sub-basin. Based on this map, more than 1.700 dip data, and comprehensive image interpretations, a stepwise restoration of a representative cross-section has been done to unravel the geological evolution of the basin from the early stages of development to its subsequent contractional deformation. On it, a flap and halokinetic sequences can be identified. Furthermore, a regional and a counter-regional extensional fault system affecting early syn-kinematic strata have been recognized, nowadays highly folded and overturned due to inversion. In addition, the later contractional deformation related to the Pyrenean orogeny has also been inferred, highlighting the role of inherited extensional and salt tectonics structures during the inversion.
Methane on Mars: Correlation of geomorphological features with current methane emissions
Authors: Mariani Elettra , Allemand Pascal
Published: February 2023

This research deals with the detailed study of some global-scale geomorphological structures on Mars to identify possible current or fossil methane emission points. For years, attempts have been made to understand the mechanism that led to the formation of methane on Mars and how it may have been stored to date in subsurface reservoirs. From the data recently received from satellites (Tracer Gas Orbiter on board of ExoMars, Planetary Fourier Spectrometer on Mars Express) and rovers (Mars Science Laboratory Curiosity in Gale crater) on Mars, it is possible to infer that the methane on Mars is gradually emitted into the atmosphere and most of the times is detected by these instruments. Thanks to these dataset of methane emissions during the years (since 2004 with the PFS first detections) it is possible to trace the possible points in which the upper limit concentration of methane are equal to or greater than 10 p.b.b.v. so as to select a few areas where to begin the geomorphological and mineralogical analyses for this research in order to create a global map of possible areas where current methane emissions from subsurface methane reservoirs may be recorded. For this study the focus will be on hectometric to kilometric mounds of volcanic or sedimentary origin (mud volcanoes and/or pingos like structures), chaotic terrains and fracture fields in sedimentary piles. The areas selected for this research are Coprates and Candor Chasma (Valles Marineris, Mars), Nili Fossae (Mars), Vernal crater and the surrounding of Arabia Terra (Mars) and Gale crater (Mars). All of these locations have key characteristics such as proximity to a boundary zone (Gale crater), the presence of a fracture system (Nili Fossae), presence of mud volcanoes or pingoes (Valles Marineris and Utopia Planitia): all possible incentives for the presence of methane emission spots. The aim of this project, as already mentioned, will therefore be to analyse these areas in detail, trying to understand whether they could be or have been methane emission points, with the help of the planetary analogues that can be found in Azerbaijan regarding mud volcanoes, in Canada for pingos or fracture systems in China.
Biotic and abiotic responses of the boreal forests carbon cycles to climate change and management
Authors: Wu Mousong , Zhang Xinyao , Wang Chunyu , Jansson Per-Erik , He Hongxing , Mammarella Ivan , Kolari Pasi , Zhang Wenxin , Li Sien
Published: February 2023

Boreal forests are a large carbon sink and are as important as the tropical forests due to huge carbon stock in both plants and soils. However, the boreal forests carbon sink is affected by climate change on one hand and by management on the hand in last several decades and the need for better understanding of how boreal forests respond to climate and management in a long term is still urgent. In this study we used the process-based CoupModel combining the long-term in-situ measurements to successfully constrain the energy, water and carbon fluxes modeling in a boreal coniferous forest. We noticed that during the extreme drought years, there were large impacts from temperature on boreal forests growth, but not from water and radiation. The harvest of plants has made the boreal forests exposed to lower thresholds of environmental factors, but the impacts of harvest on net carbon fluxes was found just for short period due to the higher ecosystem respiration after harvest. The calibrated model generally depicted good performance for water, energy and carbon fluxes at hourly, monthly, yearly and multi-year scales, but the systematic biases indicated that considering the elevated atmospheric CO2 and nutrients dynamics, the climate variations as well as the more detailed management impacts on boreal ecosystems is of importance. Our study provided new insights into the boreal forests responses to climate change and management over a long period and contributed to better understanding of boreal forests for both the modeling and observation communities.
Tracking storms in the Pyrenees using a dense seismic network
Authors: Diaz Jordi , Ruiz Mario , Udina Mireia , Polls Francesc , Martí Davis , Bech Joan
Published: February 2023

Data acquired by a dense seismic network deployed in the Cerdanya basin (Eastern Pyrenees) is used to track the temporal and spatial evolution of meteorological events such as rainfall episodes or thunderstorms. Comparing seismic and meteorological data, we show that for frequencies above 40 Hz, the dominant source of seismic noise is rainfall and hence the amplitude of the seismic data can be used as a proxy of rainfall. The interstation distance of 1.5 km provides an unprecedented spatial resolution of the evolution of rainfall episodes along the basin. Two specific episodes, one dominated by stratiform rain and the second one dominated by convective rain, are analyzed in detail, using high resolution disdrometer data from a meteorological site near one of the seismic instruments.Seismic amplitude variations follow a similar evolution to radar reflectivity values, but in some stratiform precipitation cases, it differs from the radar-derived precipitation estimates in this region of abrupt topography where radar may suffer antenna beam blockage. Hence, we demonstrate the added value of seismic data to complement other sources of information such as rain-gauge or weather radar observations to describe the evolution of ground-level rainfall fields at high spatial and temporal resolution. The seismic power and the rainfall intensity have and exponential relationship and the periods with larger seismic power are coincident. The time periods with rain drops diameters exceeding 3.5 mm do not result in increased seismic amplitudes, suggesting that there is a threshold value from which seismic data are no longer proportional to the size of the drops.Thunderstorms can be identified by the recording of the sonic waves generated by thunders. We show that single thunders can be recorded to distances of a few tens of kilometers. As the propagation of these acoustic waves is expected to be strongly affected by parameters as air humidity, temperature variations or wind, the seismic data could provide an excellent tool to investigate atmospheric properties variations during thunderstorms.
Influence of soil cover on surface runoff, infiltration, and percolation
Authors: Neumann Martin , Kavka Petr , Tejkl Adam , Laburda Tomáš , Beck-Broichsitter Steffen
Published: February 2023

The main goal of this study was to determine the effect of surface cover on soil percolation. Many previous papers have focused on reducing soil loss on steep slopes using geotextiles, but not on the intensity of percolation. Reducing surface runoff can help reduce soil loss, but increased infiltration can also increase the risk of slope collapse. For this research, Enkamat 7220 (plastic geotextile) in six different cover variations was used, as well as bare soil for comparison. A laboratory rainfall simulator with variable rainfall intensity and adjustable slope was used for the experiments, which were conducted at rainfall intensities of 60-160 mm/h. The results showed that the lowest soil percolation occurred on the plot with bare soil and on the plot where the entire surface was covered with geotextile and fully backfilled, likely due to soil compaction. The highest percolation was observed on the plot where the geotextile was fixed on top of the surface using ground anchors. The hypothesis that percolation at the foot of the slope is higher than at the top of the slope due to surface and subsurface flow was also confirmed. In future studies on the effectiveness of geotextiles, additional measurements of percolation would be beneficial for a deeper understanding of these processes. This research was supported by the research projects QK22010261, SS05010180 and CTU in Prague, grant No. SGS OHK1-086/23/11143.
The influence of canopy structural traits on the understorey air temperature of tropical forests in Borneo
Authors: Ghiznoni Santos Erone , Svátek Martin , Henrique Nunes Matheus , Eiji Maeda Eduardo
Published: February 2023

Changes in vegetation structure caused by selective logging have direct impacts on energy exchange and ecosystem functioning, which may result in altered microclimate. In this study, we investigated how selective logging affected microclimate temperatures in tropical forests of Malaysian Borneo. We used structural metrics derived from Terrestrial Laser Scanner (TLS) obtained in 16 permanent forest plots distributed over a logging intensity gradient. The plots were located within the Stability of Altered Forest Ecosystems (SAFE) Project, the world’s largest forest fragmentation experiment. TLS point clouds were used to calculate the following forest structural traits: Canopy Ratio (CR), Effective Number of Layer (ENL), Foliage Height Diversity (FHD), total Plant Area Index (PAI) and PAI layered for each 5 m height, Relative Height (RH) at 25, 50, 75, 95 and 98 percentiles. TOMST-TMS-4 microclimate dataloggers were installed in the centre of each plot to monitor air temperature at 15 cm above ground every 15 minutes during the year 2019. We then tested whether canopy traits derived from TLS point clouds could explain the variability of minimum, mean and maximum air temperature. We found that not recently logged forest plots had consistently lower understory temperatures and lower daily variability in comparison with heavily logged forest plots. Mean daily temperatures decreased by 0.9 °C for each PAI unit. PAI alone, however, could capture only 21% of the microclimate variability between plots, suggesting that structural metrics accounting for the vertical distribution of vegetation are key for a comprehensive understanding of how disturbances arising from logging affect energy dissipation in tropical forests.
Observational study on mixing in a stratified scour hole due to the wind-driven lateral circulation in a semi-closed estuary
Authors: Ebrahimi Erami Fateme , Kitsikoudis Vasileios , Vermeulen Bart , Hulscher Suzanne
Published: February 2023

Salt intrusion occurring in estuarine environments can be aggravated by the presence of scour holes in the bed. Saltwater has a higher density than freshwater. Therefore saltwater accumulates in scour holes which may exacerbate the salinization of freshwater once it is entrained by wind or other forcings. Wind can contribute to estuarine circulation and stratification through three main mechanisms: direct wind mixing, wind straining and wind-driven lateral circulation. Previous studies (Csanady, 1982; Winant, 2004), suggest that horizontal wind circulation mostly comes into play in estuaries with laterally varying bathymetry, which is the case for our study site. The Haringvliet estuary in the Rhine-Meuse delta is a former tidal basin in the western part of the Netherlands; it varies in bathymetry and has been closed off by floodgates. The gates are only opened during ebb tide to discharge river into the sea, and also for a short period of time during flood tide for ecological purposes. The complex geomorphology of the estuary is composed of shoals and deep scour holes. An extensive field campaign was carried out for over six months in the Haringvliet, at the locations of the scour holes, in which we measured flow velocity, salinity, discharge, and wind speed and direction. Results indicate that, under an axial wind over the estuary, a horizontal circulation forms by downwind flow over shoals and upwind flow in the deep channels. Based on the collected dataset, a change from a down-estuary to an up-estuary wind direction occurred while the floodgates were closed. As a result of the wind influence, the flow direction in the stratified deep channel changed quickly, which provided sufficient shear and turbulence in the whole water column for vertical mixing. The sharp drop in the salinity concentration corresponding to the mixing and flushing in the scour hole occurred due to the wind-induced lateral circulation without having high river discharge. This research shows that, in a semi-closed estuary like the Haringvliet, lateral currents and the momentum transfer corresponded to that can exert a predominant control on estuarine circulation and stratification.Acknowledgments: This research was funded by the Netherlands Organisation for Scientific Research (NWO), research program SALTISolutions with project number P18-32. Rijkswaterstaat, the Dutch Ministry of   Infrastructure and Water Management, is thanked for providing extensive field data for this research. References: Csanady, G.T., 1981. Circulation in the coastal ocean. In Advances in geophysics (Vol. 23, pp. 101-183). Elsevier.Winant, C.D., 2004. Three-dimensional wind-driven flow in an elongated, rotating basin. Journal of Physical Oceanography, 34(2), pp.462-476.
Direct observation of Earth’s spectral longwave feedback parameter
Authors: Roemer Florian E. , Buehler Stefan A. , Brath Manfred , Kluft Lukas , John Viju O.
Published: February 2023

The spectral longwave feedback parameter λν represents how Earth’s outgoing longwave radiation adjusts to temperature changes and is thus the detailed fingerprint of all longwave feedbacks, directly impacting Earth’s climate sensitivity. Most research so far has focused on the spectral integral of λν. Spectrally resolving λν permits inferring information about the vertical distribution of longwave feedbacks, thus gaining a better understanding of the underlying processes. However, investigations of λν have so far been largely limited to model studies, and no observational study we are aware of has inferred the global all-sky λν.Here we show that it is possible to directly observe the global all-sky λν using satellite observations of seasonal and interannual variability taken by the Infrared Atmospheric Sounding Interferometer (IASI). We find that spectral bands subject to strong water vapour absorption exhibit a substantial stabilising net feedback. We demonstrate that this stabilising feedback is partly caused by changes in relative humidity with warming, the radiative fingerprints of which can be directly observed. Therefore, our findings emphasise the importance of better understanding processes affecting future trends in relative humidity. This first observational constraint on the global all-sky λν can be used as a powerful tool to evaluate the representation of longwave feedbacks in global climate models and to better constrain Earth’s climate sensitivity.
Analysis of the impacts of droughts on the water quality of the transboundary German-French Lauter catchment with SWAT
Authors: Liu Xiaowei , de Jong Carmen
Published: February 2023

Current state-of-art studies have been largely focusing on analysing how headwater catchment characteristics influence the sensitivity of the water yield in response to climate change. However, there has been little research combining both hydrological analysis with in situ water quality assessment and understanding how extreme climate events could influence the water quality of the headwater catchment, especially under anthropogenic stress. Therefore, this research aims at understanding the mechanisms of how different types of droughts modify the water quality of an anthropogenically impacted catchment.The research is performed on the Lauter river, which takes its source from two headstreams, the Scheidbach and the Wartenbach in the Palatinate Forest, Rhineland-Palatinate and flows between the French-German border and ultimately flow into the Rhine River. The discharge time series of 59 years and water quality data of 48 years are being analysed. We will present the methodology of the research and current updates on the progress. The research is planned to proceed in three steps, 1) understanding the water partitioning mechanism and defining different drought types by using the SWAT (The Soil & Water Assessment Tool), 2) studying the water quality behavior under different hydrologic scenarios by conducting in situ water quality monitoring experiments, 3) predicting the water quality trend under future climate change and anthropogenically impacted scenarios. Current results include water quantity trend analysis based on the daily flow rate data at the Salmbacher Passage measuring station on the Lauter river and a primary catchment modeling result with the SWAT.Keywords: Drought, Water quality, SWAT model, Headwater catchment
The GASPOC project and the global offshore atlases of siting parameters
Authors: Larsén Xiaoli , Imberger Marc , Davis Neil , Sørensen Jacob , Kofoed Carsten , Nielsen Jim , Olsen Bjarke , Fischereit Jana , Badger Jake
Published: February 2023

The Global Atlas of Siting Parameters for Offshore and Coasts (GASPOC) project aims at shortening the project development period for offshore wind farms, with faster energy integration, lower capital expenditure and lower operating expense. This value is brought by the partners DHI, DTU Wind, Vento Maritime and DECK1 through automatic data driven downscaling techniques, that are applied to meteorological, ocean and wave modeling and analytics, including the application to real test scenarios. GASPOC provides metocean data, including siting parameters for offshore wind turbines such as extreme winds and turbulence intensity, as well as extreme waves and joint wind-wave statistics. An ensemble of reanalysis data together with the spectral correction method (Larsén et al. 2012) is used to obtain the effective 10-min extreme winds at 50 m, 100 m, 150 m and 200 m, while the calculation of the turbulence intensity at heights above the surface layer also takes the mesoscale turbulence into consideration. We show the data of the siting parameters from GASPOC which support seamless application to strategic planning of offshore wind energy development.ReferenceLarsén X., Ott S., Badger J., Hahmann A. N. and Mann J. 2012: Recipes for correcting the impact of effective mesoscale resolution on the estimation of extreme winds. Journal of applied meteorology and climatology, Doi:10.1175/JAMC-D-11.090, vol 51, No. 3, p521-533.
The coming extinction of land mammals - The next great mass extinction
Authors: Farnsworth Alexander , Lo Eunice , Valdes Paul , Buzan Jonathan , Wakeford Hannah , Scotese Chris
Published: February 2023

Mammals have dominated the Earth for the last ~55 Myr. Mammals have shown remarkable adaptation and resilience to climate change. However, it is unknown how long the Earth will be able to continue to sustain mammalian life. Estimates suggest the ultimate demise of all life will be in a ‘Venusian’ style runaway greenhouse climate ~1.5 billion years where increasing solar luminosity (L☉) will raise temperature beyond that able to sustain life. However, conditions may develop sooner that will render the Earth naturally inhospitable to mammals. In ~250 million years all the continents of the world come together to form the Earth's fourth supercontinent, Pangea-Ultima. A natural consequence of the creation and decay of Pangea-Ultima will be extremes in pCO2, both low (silicate weathering) and high (volcanic degassing). Here we show that variations in pCO2, increased solar luminosity (~2% greater than now), and extreme continentality will lead to extreme climate states that are inhospitable to mammalian life. We assess the impact of these climate states on mammalian physiological limits using dry-bulb, wet-bulb, and Humidex stress indicators as well as planetary habitability index. Although low pCO2 states will increase habitability, snowball Earth conditions may occur if the silicate weathering-pCO2 burial feedback becomes too strong (resulting in low pCO2 values <280ppm) under increased L☉. Likewise, small short-term spikes in pCO2 (≥1120ppm) outgassing will lead to extremes in heat. Under such conditions, thermal tolerances of endotherms will exceed physiological limits leading to mass extinction. The results reported here also show that global landmass configuration, pCO2, and solar luminosity play a critical role in planetary habitability.