bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigating Miocene Mediterranean-Atlantic Gateway Exchange (IMMAGE): the first land-2-sea drilling project
Authors: Flecker Rachel , Gaitonde Olivia ,   IMMAGE Co-I Team
Published: February 2023

Marine gateways play a critical role in the exchange of water, heat, salt and nutrients between oceans and seas. The advection of dense waters helps drive global thermohaline circulation and, since the ocean is the largest of the rapidly exchanging CO2 reservoirs, this advection also affects atmospheric carbon concentration. Changes in gateway geometry can therefore significantly alter both the pattern of global ocean circulation and associated heat transport and climate, as well as having a profound local impact.
Today, the volume of dense water supplied by Atlantic-Mediterranean exchange through the Gibraltar Strait is amongst the largest in the global ocean. For the past five million years this overflow has generated a saline plume at intermediate depths in the Atlantic that deposits distinctive contouritic sediments in the Gulf of Cadiz and contributes to the formation of North Atlantic Deep Water. This single gateway configuration only developed in the early Pliocene, however. During the Miocene, a wide, open seaway linking the Mediterranean and Atlantic evolved into two narrow corridors: one in northern Morocco; the other in southern Spain. Formation of these corridors permitted Mediterranean salinity to rise and a new, distinct, dense water mass to form and overspill into the Atlantic for the first time. Further restriction and closure of these connections resulted in extreme salinity fluctuations in the Mediterranean, leading to the formation of the Messinian Salinity Crisis salt giant.
IMMAGE is a land-2-sea drilling project designed to recover a complete record of Atlantic-Mediterranean exchange from its Late Miocene inception to its current configuration. This will be achieved by targeting Miocene offshore sediments on either side of the Gibraltar Strait with IODP during Expedition 401 (December 2023-February 2024) and recovering Miocene core from the two precursor connections now exposed on land with ICDP. The scientific aims of IMMAGE are to constrain quantitatively the consequences for ocean circulation and global climate of the inception of Atlantic-Mediterranean exchange; to explore the mechanisms for high amplitude environmental change in marginal marine systems and to test physical oceanographic hypotheses for extreme high-density overflow dynamics that do not exist in the world today on this scale.
How different thinning can improve carbon sequestration, carbon stock and mechanical stability in peri-urban mixed forest stands: a study case in Mediterranean environment.
Authors: Chiavetta Ugo , Mazza Gianluigi , Paletto Alessandro , De Meo Isabella , Di Carlo Marco , Lagomarsino Alessandra , Cantiani Paolo
Published: February 2023

Peri-urban plantations - artificial forests located near urban areas - in the Mediterranean context are often degraded due to the combined effect of human inactivity and climate changes. Degraded peri-urban forests provide fewer ecosystem services and have reduced biodiversity compared to natural and semi-natural forests.Silvicultural practices – such as thinning, pruning, weeding, planting – can increase the amount of carbon stored in trees and forests. Thinning can also create more growing space for new trees, resulting in higher carbon sequestration. Additionally, thinning in forests can increase tree mechanical stability and reduce the forest fires risk and, consequently, the related large amounts of carbon released into the atmosphere.While the main trend of the process is well known, the magnitude can vary significantly according to the climate, the starting condition of the stand, and the natural and human disturbances. All these causes can impact the payback time of carbon stocks. Payback time refers to the time span for the carbon recovering by remaining trees after thinning intervention.In this study case, we report the results of a silvicultural trial in a mixed peri-urban degraded plantation after 6 years from thinning. Three different silvicultural treatments were compared: a) moderate thinning from below (-20% of current biomass) representing the typical silvicultural treatment of Italian Apennine and considered the traditional scenario; b) intense selective thinning (-30% of current biomass) representing the innovative scenario and c) no management considered the business-as-usual scenario). We also projected the growth to estimate the payback time in recovering harvested carbon stock.The results show that the more intense thinning has a positive impact on carbon sequestration in the following years, confirming literature results. Besides, the estimated payback time was a) of about 7 years for recovering (in both thinning approaches) the harvested volume; b) of about 8 years for innovative thinning overcoming traditional one; c) of about 12 years for innovative thinning overcoming the control option; d) of about 17 years for traditional thinning overcoming the control option. Finally, we also observed a significant tree mechanical stability increasing from no management option to both thinning options after 2 years. After 6 years, we observed an additional increase of stability for the stands treated with the innovative thinning, while for stands treated with traditional thinning the difference with business as usual reduced until losing its significance.
Observation and Simulation of Solar Wind Proton Energization by Magnetic Switchback Pulse
Authors: He Jiansen , Luo Qiaowen , Zhu Xingyu , Duan Die , Verscharen Daniel , Cui Jun , Lai Hairong
Published: February 2023

Magnetic switchbacks are believed to play an important role in the heating of solar corona and solar wind as well as the acceleration of solar wind in the inner heliosphere. To address this issue, we conduct a comprehensive study involving observational analysis and numerical simulation.

In the first part, we analyze magnetic field data and plasma data measured by PSP during its encounters, and select 71 switchback events with reversals of the radial component of the magnetic field and unchanged electron-strahl pitch angles. We investigate the anisotropic thermalization of switchbacks in a statistical study of the measured proton temperatures in the parallel and perpendicular directions as well as proton density and specific proton fluid entropy. We apply the ``Genetic Algorithm" (GA) method to directly fit the measured velocity distribution function (VDF) in field-aligned coordinates using a two-component bi-Maxwellian distribution function. We find that the protons in most switchback events are hotter than outside the switchbacks, with characteristics of parallel and perpendicular heating. Specifically, significant parallel and perpendicular temperature increases are seen for 45 and 62 of the 71 events, respectively. We find that the density of most switchback events decreases rather than increases, which indicates that proton heating inside the switchbacks is not caused by adiabatic compression, but is probably generated by non-adiabatic heating caused by field-particle interaction. Accordingly, the proton fluid entropy inside the switchbacks is higher than that in the ambient solar wind. In PSP observation, a significant portion of the proton VDFs is obscured by the spacecraft’s heat shield and therefore lies outside SPAN’s field of view, so simulation is an extra crucial method to study the heating effect of switchbacks.

In the second part, we perform a test-particle simulation with a background magnetic field, and introduce test-particles to explore how magnetic switchbacks affect their energization. We introduce square waves to imitate recurrent switchback intervals and their ambient quiet intervals between which fluctuating magnetic field have different angles. Besides, Boris algorithm is employed to advance the motion of test-particles in the time varying electromagentic fields. We report the following three findings after analyzing the simulation results. (1) When the amplitude of simulated switchback increases, the heating effect of test-particles is more prominent. (2) The velocity distribution of test-particles is temporarly modulated by the encouter of switchback interval. (3) Preferential perpendicular heating of test-particles can be observed.
The Firefly Constellation: The Need for a Wholistic View of the Sun and its Environment
Authors: Raouafi Nour E. ,   The Firefly Constellation Team
Published: February 2023

Firefly is an innovative mission concept study for the Decadal Survey for Solar and Space Physics (Heliophysics) 2024-2033 to fill long-standing knowledge gaps in Heliophysics. A constellation of spacecraft will provide both remote sensing and in situ observations of the Sun and heliosphere from a whole 4π-steradian field of view. The concept implements a holistic observational philosophy that extends from the Sun’s interior, to the photosphere, through the corona, and into the solar wind simultaneously with multiple spacecraft at multiple vantage points optimized for continual global coverage over much of a solar cycle. The mission constellation includes two spacecraft in the ecliptic and two flying as high as ~70º solar latitude. The ecliptic spacecraft will orbit the Sun at fixed angular distances of ±120º from the Earth. Firefly will provide new insights into the fundamental processes that shape the whole heliosphere. The overarching goals of the Firefly concept are to understand the global structure and dynamics of the Sun’s interior, the generation of solar magnetic fields, the origin of the solar cycle, the causes of solar activity, and the structure and dynamics of the corona as it creates the heliosphere. We will provide an overview of the Firefly mission science and architecture and how it will revolutionize our understanding of long-standing heliospheric phenomena such as the solar dynamo, solar cycle, magnetic fields, solar activity, space weather, the solar wind, and energetic particles
Sub-surface dust thickness and ice content in the nucleus of comet 67P/Churyumov-Gerasimenko constrained with Rosetta observations
Authors: von Allmen Paul , Jhalani Vatsal , Lee Seungwon
Published: February 2023

We computed the total water vapor outgassing rate for comet 67P/Churyumov-Gerasimenko for a time period spanning several months before and after the perihelion in 2015. The two-layer surface model includes time-dependent solar illumination, thermal emission, sublimation, heat transport into the nucleus, and gas diffusion through the dust layer. The model parameters include among others the thickness of the top dust layer and the ice content in the bottom layer. We fitted the model parameters so that the temporal evolution of the computed water outgassing rate matches published outgassing rates derived from observations with the Microwave Instrument for the Rosetta Orbiter (MIRO). We will discuss the evolution of the retrieved dust thickness and ice content before and after perihelion and the variations between the northern and southern hemispheres of the nucleus.
Fluid-pressure induced eclogitisation of a dry granulite: Insights from Hydro-Chemical model
Authors: Bras Erwan , Yamato Philippe , Duretz Thibault , Schmalholz Stefan , Podladchikov Yury
Published: February 2023

Eclogitization constitutes one of the most emblematic transformations in continental subduction zones, where conversion of initially dry lower crustal rocks into eclogite facies rocks correlates with the occurrence of seismogenic events. This reaction is generally considered to occur at high pressure conditions during hydration of dry granulite. Several models using « ad hoc » diffusion equation exist to model this hydration process and the consequences of reaction-induced changes in terms of rheology and density. However, to our knowledge, there is no quantitative model allowing to physically explain how fluids propagate inside a dry rock (i.e. with no porosity at all) and how reaction-induced alteration front widens over time. In this study, we therefore propose a new fully coupled hydro-chemical model wherein a two-phase flow model is coupled with the eclogitization reaction. We use a mass conservative approach, solving total mass and solid mass equations, in a closed isothermal system. Fluid and solid densities are calculated with lookup tables from equilibrium thermodynamics. Our model shows that a fluid pressure pulse generates a pressure gradient that can be associated with the densification reaction when the pressure required for the eclogitization is reached. This reaction generates a large increase in porosity (0 to ~16%) and subsequent porous fluid flow inside the initially dry granulite. This process is then sustained as long as the fluid pulse is maintained, and ends shortly after the fluid pressure pulse stops. However, high pressure within the reacted area can persist for a long period of time. A parametric study allowing to constrain both the duration and the widening of the reaction area is proposed as well as an application to the emblematic case study of the eclogitized granulites of Holsnoy (Bergen Arcs, Norway).
Recent Changes in Onset and Withdrawal Characteristics of Monsoon over India in Relation to Variability of SST and Convection over the Indian Ocean
Authors: Pattanaik Dushmanta Ranjan
Published: February 2023

The  onset  of  the  southwest  monsoon  over  Kerala  (Southern tip of India) is  very  crucial  as  it  marks  the  beginning  of  the rainy  season  for  Indian  land  mass.  The  onset  of  the  broad  scale  Asian  monsoon  occur  in  many  stages  associated with the significant  transitions  in  the  large-scale  atmospheric  and  ocean  circulations  over  the  region.  Along with this, the changes in sea surface temperature (SST) and convective activity over the north Indian Ocean also play crucial roles during the onset and advance of monsoon over India. Recent analysis (based on data from 1971 to 2019) by India Meteorological Department (IMD) on the onset & withdrawal of southwest monsoon over India compared to the earlier onset and withdrawal dates (based on the rainfall data from 1901 to 1940) has found variations in onset and withdrawal dates over different parts of India.         The variability of SST and convective activity over the north Indian Ocean (Bay of Bengal and Arabian Sea) on inter-annual time scales and their association with the onset and withdrawal of southwest monsoon over India has been analysed by using 42-year (1980-2021) monthly mean outgoing longwave radiation (OLR) data. The 42-year period is categorised into two groups of 21 years each (Former: 1980-2000 & Later: 2021-2021). The inter-annual variability of SST shows significant increasing trends over the Arabian Sea and the Bay of Bengal with a comparatively higher rate of increase of SST over the Arabian Sea. Associated with this increasing SST, the degree of moist static convective instability and associated convective rainfall is also increasing during later period compared to the former period with a magnitude of difference is higher over the Arabian Sea compared to the Bay of Bengal.         The analysis also indicated that there is a rapid progress of monsoon to the north after its onset over the southern tip of India leading to early onset over parts of northern India.  Similarly, there is a delayed withdrawal of monsoon from northwest India in later period compared to the former period, which is basically, due to the increasing convective activity over the north Arabian Sea and neighbourhood during the onset and withdrawal phase of monsoon.
Mapping peat layer thickness using machine learning and aerial laser scanning data
Authors: Ivanovs Janis , Lazdiņš Andis
Published: February 2023

The surface of the earth's surface together with the granulometric composition of the soil are among the main parameters that determine the flow and accumulation of surface and underground water. Poorly drained and wet soils are important for biodiversity, water exchange, various chemical and biological processes, as well as for organic carbon accumulation. This research was done within the framework of the project Demonstration of climate change mitigation potential of nutrients rich organic soils in Baltic States and Finland (OrgBalt) and its purpose is to map the thickness of the organic layer on a national scale for the territory of Latvia. The mapping was done using machine learning methods and NFI sample plot data on peat layer thickness, ALS laser scanning data and other additional data were used as training data. As a result, a raster map was obtained, which depicts the depth of the peat layer in three different classes - No peat, peat layer thickness from 1 to 20 cm and peat layer thickness more than 20 cm. The accuracy of the machine learning classification algorithm reaches 0.88, while the kappa value is 0.74. Separately by different classes, the sensitivity of the model is 0.94 for the first class, 0.63 for the second class and 0.81 for the third class.
Habitat suitability modelling of coralligenous in the Northern Adriatic Sea and potential distribution under climate change scenario
Authors: Vitelletti Maria Letizia , Manea Elisabetta , Bongiorni Lucia , Ricchi Antonio , Sangelantoni Lorenzo , Bonaldo Davide
Published: February 2023

Climate change is deeply affecting oceanographic, biogeochemical, and hydrological processes and consequently influencing the ecological patterns of ecosystems. Indeed, marine habitats and species are facing many alterations in their structure, functioning, and in their capacity of providing ecosystem services. To investigate and explore the distribution and potential variation of habitats and species under future climate change scenarios, Habitat Suitability Models (HSMs) have been widely applied during the last years for their recognized ability in predicting the suitability of a location for species and habitats in correlation with the environmental conditions.With the application of two of the best-known HSMs (Random Forest and MaxEnt), this research intends to investigate the distribution of the coralligenous, a widespread habitat in the Northern Adriatic Sea threatened by the effects of climate change, and identify its potential variation in a severe future scenario. The analysis consisted in examining the correlation between the habitat distribution with environmental parameters obtained from online databases and a set of dedicated ocean model simulations applied in recent past conditions and under RCP 8.5 climate change scenario. Furthermore, to explore the potential uncertainty of the environmental variables in future conditions, a sensitivity analysis has been implemented by running additional HSMs simulations set up with variables' increments and decrements resulting from projections modeled by other research.The models perform very well in predicting habitat distributions. The prediction under the climate change scenario shows that opportunistic species (e.g. turf-dominant algae) find more suitable conditions in the area being more tolerant to stressful conditions and alterations of the environmental variables. As a result, calcareous macroalgae appear to be more vulnerable to climate change effects, including increases in temperature, nutrient concentrations, salinity, and velocity. Overall, the results of the sensitivity analysis confirmed the results predicted by models; however, Random Forest also shows a higher sensitivity to uncertainty than MaxEnt.In conclusion, this study gives a sight of the likely ecological behavior in correlation with past environmental conditions and future alterations due to climate change. Besides, HSMs confirm to be very useful tools to develop adequate conservation strategies and/or identify priority areas to protect. Thanks to the sensitivity analysis, additional hints about the models’ behavior according to the environmental uncertainties are extrapolated, allowing to consider with consciousness the results and understanding of the potentialities of the models according to the data in possession.
A porous-media model for reactive fluid-rock interaction in a dehydrating rock
Authors: Zafferi Andrea , Huber Konstantin , Peschka Dirk , Vrijmoed Johannes , John Timm , Thomas Marita
Published: February 2023

We discuss a model for temperature-induced rock dehydration that features fluid liberation through mineral reactions, diffusion of chemically released species, and flow through porous media. This model can be derived either by considering standard conservation laws and flux definitions (Pl¨umper et al.[2017], Beinlich et al. [2020]) or, alternatively, using the variational framework of GENERIC (General Equations for Non-Equilibrium Reversible Irreversible Coupling)(Zafferi et al. [2021]) introduced by M. Grmela and H.C. ¨ Ottinger. The latter approach is based on the abstract definition of thermodynamical driving potential and operators characterizing the reversible and dissipative contributions of the processes. By doing so we can show that local equilibrium assumptions are recovered as fast limit of irreversible processes. Ultimately, we rigorously prove that the PDE model so derived admits solutions using a discretization strategy that imitates the numerical implementations.ReferencesAndreas Beinlich, Timm John, Johannes C Vrijmoed, Masako Tominaga, Tomas Magna, and Yuri Y Podladchikov. Instantaneous rock transformations in the deep crust driven by reactive fluid flow. Nature Geoscience, 13(4):307–311, 2020.Oliver Plümper, Timm John, Yuri Y Podladchikov, Johannes C Vrijmoed, and Marco Scambelluri. Fluid escape from subduction zones controlled by channel-forming reactive porosity. Nature Geoscience, 10(2):150–156, 2017.Andrea Zafferi, Dirk Peschka, and Marita Thomas. Generic framework for reactive fluid flows. ZAMM-Journal of Applied Mathematics and Mechanics/Zeitschrift für Angewandte Mathematik und Mechanik, page e202100254, 2021.
Dynamics and impact of diurnal warm layers in the ocean
Authors: Schmitt Mira , Sarkar Sutanu , Pham Hieu T. , Umlauf Lars
Published: February 2023

Thin Diurnal Warm Layers (DWLs) form near the surface of the ocean on days of large solar radiation,weak to moderate winds, and small surface waves. DWLs are characterized by complex dynamics,and are relevant to the ocean especially by modifying surface-layer mixing and atmosphere-oceanfluxes. Here, we use idealized Large Eddy Simulations (LES) and second-moment turbulencemodelling, both including the effects of Langmuir turbulence, to identify the key non-dimensionalparameters of the problem, and explore DWL properties and dynamics across a wide parameterspace. Comparison of LES and the second-moment turbulence models shows that the latter providean accurate representation of the DWL structure and dynamics. We find that, for equilibrium waveconditions, Langmuir effects are significant only in the Stokes layer very close to the surface. Whilewe see pulses in the turbulent stresses and shear in the LES, there are no relevant effects ofLangmuir turbulence on DWL bulk properties and total entrainment. Results of the parameter spaceanalysis agree with the midday scaling by Pollard et al. (1986), however, with modified modelcoefficients and deviations of up to 30% especially at high-latitudes. We develop non-dimensionalexpressions for the strength and timing of the DWL temperature peak in the afternoon, and discussthe mixing efficiency and energetics of DWLs in the presence of Langmuir turbulence.
Enhancing the science-policy-practice nexus for effective and sustainable wetland Management in Southern Africa
Authors: Nyatoro Dzikamayi Tanaka , Onema Jean-Marie Kileshye , Tacheba Budzanani , Olwoch Jane
Published: February 2023

Effective natural resources management, especially of wetlands, are vital for the sustainability of livelihoods. This is further buttressed in Southern Africa where competing uses and users are increasingly putting pressure on these finite resources. The Southern African Science Service Centre for Climate Change and Adaptive Land Management (SASSCAL) with financial support from the African Union and the European Commission in the framework of the GMES programme endeavoured to develop a geoportal tool for effective wetland Management through a project called Wetland Monitoring and Assessment Service for Transboundary Basins in Southern Africa (WeMAST). WeMAST has an emphasis on capacity building and awareness raising for wetland assessment and monitoring in the following four transboundary river basins (Cuvelai, Okavango, Limpopo and Zambezi) across the SADC region. The WeMAST geoportal, developed during phase one, provides hydro-meteorological and physiographic attributes assessment and monitoring of wetlands. These include the spatial and temporal extent and status of wetlands, land cover and uses dynamics, flooding, vulnerability and fire indices. For the second phase, WeMAST puts emphasis on developmental impact on the ground hence some deliberate efforts are in place in order to enhance synergies between the scientists behind the concepts, the users, private sector and local communities on the ground as well as policy makers with the overall responsibilities of guiding the implementations of developmental pathways. In Phase II, policy and decision makers in the target countries (Angola, Botswana, Namibia, South Africa, Zambia and Zimbabwe) need to support upscaling and operationalization of the WeMAST geoportal.  As a result, the project consortium has now been designed in order to foster more interactions between stakeholders involved in wetland management through knowledge brokerage events where the geoportal tool, its products and services are disseminated, tested and validated to a great extent. Similarly an interface with policy makers has been established within the consortium through WaterNet via the Water Resources Technical Committee (WRTC) in order to appraise and involve SADC ministers in charge of water and natural resources management twice annually. The innovative and well-crafted approach of the WeMAST project under GMES offers a considerable room for enhanced synergies between policy makers, Scientists, the private sector and practioners for sustainable and effective wetland Management in the SADC region.
Trade-offs and synergies of carbon sequestration in global agricultural soils: a literature synthesis
Authors: Goberna Estellés Marta ,   TRACE-Soils Team
Published: February 2023

Agricultural management practices aimed at sequestering carbon (C) in soils can have synergies with many agroecosystem services, but may come at the cost of increased greenhouse gas (GHG) emissions and nutrient losses. We performed a systematic literature synthesis to review whether C sequestration practices show synergies with soil structure and soil biota, but generate trade-offs in terms of CO2 and N2O emissions or N and P losses worldwide. We also assessed whether the magnitude of trade-offs and synergies vary across climatic regions and over time.We performed systematic literature searches in the Web of Science for articles that: 1. experimentally assess the effect of minimising soil disturbance, diversifying agroecosystems, and/or increasing organic matter inputs versus standard practices, and 2. include measurements of C sequestration and at least another response variable related to synergies or trade-offs. We retrieved 771 publications, 537 of which were excluded based on i) the type of article (review, opinion papers), ii) a focus on non-soil habitats, forests or organic soils, or iii) experimental designs not matching our criteria. We included 234 studies that report 572 effects of sustainable practices on 228 sites located in 38 countries. Experiments averaged 10 years of monitoring and the majority reported effects of increasing organic matter inputs and minimising soil disturbance (88%) in temperate and continental climates (75%). Soil organic C increased without compromising crop yields considering all management practices together, i.e. positive effects of sustainable versus standard practices on C sequestration were more frequent than expected by chance. As expected, C sequestration promoted soil biota, but effects were more evident on biomass than on diversity. We also detected synergistic effects on soil aggregation, porosity, water retention and compaction. Negative effects of C retention practices were significant when considering GHG emissions and nutrient losses, particularly for CO2 emissions and mineral N accumulation. However, the magnitude of these trade-offs varied significantly depending on the metrics used to measure them, e.g. field versus lab GHG fluxes. We discuss how these effects vary across management practices, time and space, and review main knowledge gaps detected in the literature.
Modelling the ocean circulation and mixing processes of the Last Glacial Maximum using the Community Earth System Model (iCESM1.2) and the Internal Wave Mixing parameterization IDEMIX
Authors: Pilatin Heves , Paul André , Pollmann Friederike , Schulz Michael
Published: February 2023

The Last Glacial Maximum (~21 ka) is the most recent glacial period when the ice sheetcoverage was at its greatest extent (8% of Earth's surface), and the atmospheric CO2concentration was ~190 ppm. During this period, the continental shelves were exposed andthe global-mean sea level was lower by ~130 m compared to today. This project hypothesizesthat decrease in sea level caused tidal-energy dissipation to shift from the shelves to the open-ocean resulting in enhanced vertical mixing in the deep ocean. The aim of this project is tostudy the global ocean circulation and the marine biogeochemical processes of the LGMclimate state using an energetically consistent ocean mixing scheme: Internal WaveDissipation, Energy, and Mixing (IDEMIX) in the fully coupled isotope-enabled EarthSystem Model (iCESM1.2). For this study, only the tidal-induced mixing is investigated.Hence the tidal forcing is considered as the only source for generating internal waves inIDEMIX parameterisation. The model uses the "KPP+IDEMIX" approach as the combinedvertical mixing parameterization. While the KPP is activated only in the mixed layer (up to ~1 km), IDEMIX is applied only to the interior ocean, where the dissipation is generated by thetidal forcing at the ocean floor. In our simulations, we use 2° resolution for the atmosphereand 1° for the ocean, and we simulate LGM and pre-industrial climate states with and withoutIDEMIX. The modal bandwidth tuning parameter (j★) in IDEMIX determines the number ofexcited vertical modes, which affects how fast the energy propagates from the bottom to theupper ocean. We perform the sensitivity experiments by using different j★ values in our LGMsimulations and investigate its impact on the vertical mixing and the ocean state.
Building Storylines of Future Atmospheric River Floods
Authors: Griffith Helen , Cloke Hannah
Published: February 2023

A storyline is defined as a physically self-consistent unfolding of past events or of plausible possible futures (Shepherd et al., 2018). It has advantages in effective risk communication and adaption, as it moves the emphasis away from probability across to plausibility (Butler et al., 2020). Working as part of the EvoFlood (Quantifying the Evolution of Flood hazard and risk across a changing world) project, this work presents a novel methodology for estimating future hydrology based on not only climatic drivers, but the wider impacts of dams, river regulation and changing land-use. Grounded in historical atmospheric river floods, storylines are extracted from the large ensemble reforecast dataset provided by the Global Flood Awareness System (GloFAS; http://www.globalfloods.eu/).Butler, J. R. A., Bergseng, A. M., Bohensky, E., Pedde, S., Aitkenhead, M., & Hamden, R. (2020). Adapting scenarios for climate adaptation: Practitioners’ perspectives on a popular planning method. Environmental Science & Policy, 104, 13–19. https://doi.org/10.1016/j.envsci.2019.10.014Shepherd, T. G., Boyd, E., Calel, R. A., Chapman, S. C., Dessai, S., Dima-West, I. M., Fowler, H. J., James, R., Maraun, D., Martius, O., Senior, C. A., Sobel, A. H., Stainforth, D. A., Tett, S. F. B., Trenberth, K. E., van den Hurk, B. J. J. M., Watkins, N. W., Wilby, R. L., & Zenghelis, D. A. (2018). Storylines: An alternative approach to representing uncertainty in physical aspects of climate change. Climatic Change, 151(3–4), 555–571. https://doi.org/10.1007/s10584-018-2317-9
Mapping and classifying drainage ditches in forested landscapes usingLiDAR data
Authors: Melniks Raitis , Duka Martins Vanags , Lazdins Andis
Published: February 2023

Most of the long-term operational infrastructure, including the drainage ditch network, has been developed before compliance with climate change was included in the planning process. Therefore, it is essential to obtain accurate data on the location and condition of the ditch network in order to be able to assess its suitability for foreseeable conditions and the need for improvement measures. The aim of this study is to develop a mapping method for identification and classification of the drainage ditch network, which can be used for surface runoff modeling and to increase accuracy of estimation of greenhouse gas (GHG) and carbon emissions. The study area consists of 20 objects throughout Latvia with a total area of 175 km2. Digital elevation models (DEMs) in two resolutions, which were created using three different interpolation methods, were used for the analysis. Several multi-level data filtering methods were applied to identify and classify ditch network, including flow patterns, which can be used in surface runoff process. The method we developed correctly identified 85–89 % of ditches, depending on the DEM used, in comparison to the reference data. Mapped ditches are located within 3 m range of the reference data in 89–93% of cases. Ditch properties were identified within DEM resolution accuracy. The elaborated model is robust and uses openly available source data and can be used for large scale ditch mapping with sufficient accuracy necessary for hydrological modelling and GHG accounting in the national inventories.
Impact of different tree species composition and seasonality on forest stand height predictions using airborne laser scanning and National forest inventory data
Authors: Ivanovs Janis , Lang Mait
Published: February 2023

Airborne laser scanning (ALS) data has been widely used for the assessment of various forest inventory parameters, such as forest stand height, biomass, etc. However, the spatial distribution of the ALS point cloud can be affected by various factors related to the survey methodology and forest stand characteristics. This study uses national coverage high-resolution ALS data with minimum point density of 4 points per square meter in combination with National forest inventory (NFI) field data to construct forest stand height models for forest stands dominated by 6 most common tree species in Latvia in mixed forest stand conditions- Pinus sylvestris L., Betula pendula Roth, Picea abies (L.) Karst, Populus tremula L., Alnus incana (L.) Moench and Alnus glutinosa (L.) Gaertn. We also take into account the ALS technology used and variations in the growing season. The ALS point cloud data was cut along the borders of the NFI plots and a statistical analysis of the spatial distribution of points within the borders of the NFI plots was performed. The results show that the RMSE value of the linear model using all NFI plot data is 1.91m, while the data sets divided by different tree species and seasonality reach the RMSE value in the range of 1.4m to 3.8m for Scots pine and Birch respectively.Key words: Forest inventory, airborne laser scanning, phenology, large scale forest mapping
Slowly deforming metropolitan France: what can GNSS tell about physical processes ?
Authors: Metois Marianne , Periollat Axel , Mazzotti Stéphane , Masson Frédéric , Vergnolle Mathilde , Socquet Anne , Vernant Philippe , Rigo Alexis , Baize Stéphane , Piña-Valdés Jesús , Grosset Juliette
Published: February 2023

Analysis of lithospheric deformation is key to understanding current tectonics and other active deformation processes. The Alceste project, conducted in the framework of the Résif Seismicity Transverse Action, aims at proposing an updated seismic hazard model in metropolitan France built from the most recent data and academic consensus. One of the contributions will come from geodetic observations through strain rate integration in seismotectonic zoning and seismic hazard models.
Most of Western Europe in general, and metropolitan France in particular, is located within the Eurasian Plate, which has very low deformation and seismicity rates. These GNSS-derived secular velocity field could be related to the combination of different deformation processes, with a minor contribution from plate tectonics (relative plate motions, mantle convection, etc), while most of the measured velocities could be explained by non-tectonic long-term or transient processes (gravitational motions, Glacial Isostatic Adjustment, erosion, anthropogenic deformation, etc). Some of these physical processes causing surface deformation also reflect stress changes at depth that may be associated with loading on active faults and seismicity. Properly mapping this deformation is therefore a key to better assess seismic hazard in slow straining areas.
In order (i) to assess the variability due to the diversity of the strain-rate calculation methods used in the scientific community and (ii) to test their capacity to resolve low-amplitude consistent surface deformation, we conduct a benchmark exercise. We build sets of synthetic velocity fields sampled at the existing GNSS permanent stations from the RENAG (REseau NAtional GNSS Permanent), RGP (Réseau GPS Permanent) and other permanent and non-permanent benchmarks. Our synthetic velocity fields have the same characteristics (noise, uncertainties) as the observed velocities in metropolitan France but they contain surface deformation signals from known physical processes (block rotations, fault elastic loading, large scale flexure, etc). We compare the strain rate invariants derived independently by nine different RENAG research teams (using different software) to the expected strain rate patterns and discuss drawbacks and advantages of each approach. In a second step, we analyzed the strain rate tensors derived from the synthetic velocity fields to discuss potential regional style of the deformation in metropolitan France. Previous studies have shown that the computation of strain rate tensors is impacted by the user-defined parameters and the algorithm specificity used. Exploring these different biases in the strain rate solutions represent the opportunity to improve the understanding of the conventional problem of the standard interpolation.
Risks, major infrastructure and public procurementLu
Authors: Police Aristide
Published: February 2023

The paper focuses its attention on the functional interconnections that arise between unforeseen events, infrastructure planning and public contracts. Distortions are noted that alter infrastructure planning with respect to the emergence of unforeseen events that also affect the awarding of public contracts, with absent or sloppy procedures that in the long run betray the assumption for which they were called.Biases are likely to generate negative consequences in the long run, for the accountability of administrations, for the management of procedures, and of course on the infrastructure itself. It is a matter of establishing the derogation regime, the possibility of concentrating many powers under one person also in order to check the trajectories of public authorities' approach to unforeseen situations.
Mid-Miocene terrestrial carbon isotope shift driven by atmospheric CO2 in the Xining Basin, NE Tibetan Plateau
Authors: Zhao Yan , Wu Fuli , Fang Xiaomin
Published: February 2023

The Mid-Miocene Climatic Optimum (MMCO; ~17-15 Ma) possesses boundary conditions including many flora and fauna close to modern but extreme warming occurred. Clarifying the response mechanism of terrestrial ecosystem to the MMCO can provide important clues to our ecological change under the future global warming. However, the MMCO is mostly captured by abundant deep-sea deposits, related terrestrial ecosystem records are scarcely reported because of depositional hiatuses. Continuous sediments from Tashan Borehole (TSB) in the Xining Basin, northeastern Tibetan Plateau (NETP) have been dated as 18.5-13.5 Ma by high-resolution paleomagnetic studies, covering the entire MMCO. Sediment organic carbon isotope (δ13CTOC) could sensitively record its overlying plants and less restricted by preservation. Therefore, TSB δ13CTOC record was recovered in this study to investigate the NETP terrestrial ecosystem response to the MMCO. Firstly, TSB has developed a typical distal floodplain deposit and no change of local provenance appeared during 18.5-13.5 Ma, indicating that surrounding land plants served as the dominant organic source for TSB sediments. TSB δ13CTOC values range from -28.03‰ to -25.16‰, combined with the analysis by isotope mass-balance model, we deduced that C3 plants are the dominant component for the mid-Miocene terrestrial vegetation in the NETP, no obvious C4 plants have grown. Secondly, an obviously negative shift of 0.6‰ occurred in TSB δ13CTOC during ~17.6-14.2 Ma, coincides with the positive excursion of ~0.7‰ in global benthic δ13C. TSB δ13CTOC values vary negatively with the global benthic δ13C values, both in long-term Monterey Excursion event and short-term carbon maxima events. We deduced that increasing atmospheric CO2 during the MMCO lead to the higher temperature, rise of sea level and ultimately increased organic carbon burial, and simultaneouslyenhanced the carbon isotope fractionation during terrestrial C3 plants’ photosynthesis. Finally, terrestrial ecosystem in Xining Basin captured the MMCO exactly at 17.6-14.2 Ma. In a scenario of warm and humid, the carbon isotope cycle of terrestrial C3 plants is dominantly controlled by atmospheric CO2 concentration, may be also superimposed by the effect from enhanced global warming-driven precipitation.
Radar Interferometry and Tomography for the Exploration of Enceladus’ Surface and Subsurface
Authors: Benedikter Andreas , Rodriguez-Cassola Marc , Krieger Gerhard , Hussmann Hauke , Stark Alexander , Wickhusen Kai , Stelzig Michael , Vossiek Martin
Published: February 2023

Orbital Synthetic Aperture Radar (SAR) interferometry (InSAR) and tomography (TomoSAR) are key techniques for the exploration of terrestrial ice sheets that are used operationally. However, in the context of planetary exploration, these approaches are rather exotic and have not been used yet. In the frame of DLR’s Enceladus Explorer (EnEx) initiative, we propose a multi-modal, multi-frequency orbital radar mission, operating -among others- in a SAR interferometric and tomographic mode capable of delivering high-accuracy and high-resolution topography, tidal deformation, and composition measurements as well as 3-D metric-resolution imaging of the ice crust along tens of kilometers wide swaths. The ice penetration capability of radar signals allows for the exploration of both surface and subsurface features down to hundreds of meters, depending on the used carrier frequency.Multiple SAR acquisitions of the same area are needed to form interferometric and tomographic products. These acquisitions are collected successively following a repeat-pass concept using so-called periodic orbits with repeating trajectories. For the available observation geometries, the baselines between the repeat trajectories need to lie within a few hundreds of meters (i.e., the radar needs to fly within a tube of hundreds of meters). Unfortunately, the low Enceladus mass and its proximity to Saturn commonly lead to instabilities for highly inclined science orbits. We find that published orbit solutions do not exhibit sufficient stability for providing the necessary repeat passes. However, through a grid-search approach in a high-fidelity gravitational model, we identified highly stable periodic orbits that sustain the required repeat characteristic up to hundreds of days. The short repeat periods in the order of 1 to 4 days allow for a fast acquisition of InSAR observations and the formation of tomographic stacks within several days.Based on a representative system, we present global performance simulations for both InSAR and TomoSAR products with a focus on the prominent south polar plume region of Enceladus. The performance of these products depends on several factors, including the system being used, the orbital geometry, the accuracy of the guidance, navigation, and control (GNC), the accuracy of the orbit determination, and the structure and composition of the ice crust, which affects the backscatter characteristics and potential decorrelation effects in the SAR acquisitions. We use an End-to-End (E2E) simulator developed at DLR for generating realistic SAR, InSAR, and TomoSAR products. The E2E is capable of accommodating the designed orbits, the Enceladus topography, deformation models, representative backscatter maps, and decorrelation effects, as well as any relevant instrument, baseline, and attitude errors.
Identifying strategies to reduce diesel particulate matter levels in cities
Authors: George Linda , Rogers Andrew , Sarle Kirsten , DeMarco Lyndsey
Published: February 2023

Diesel emissions are ubiquitous around the world and adversely impacts human and environmental health. One of the primary pollutants of concern from diesel combustion are the solid particles formed as a byproduct of the combustion diesel fuel, known as diesel particulate matter. In regions where there is significant transport of goods, such as port cities, emissions from trucks, ships and trains can raise ambient levels of diesel particulate matter above health standards. We studied diesel emissions in Portland, Oregon USA, a mid-sized port city through a combination of source testing/evaluation, ambient monitoring and modeling (CALPUF) to produce a validated model of ambient diesel particulate matter. Similar work is starting in Rotterdam, Netherlands. Through our model we were able to identify policies that can be used to reduce emissions and ambient concentrations of diesel particulate matter. We collaborated with a state regulators and community groups identify mitigation strategies to model. For example, we modeled the potential effect of electrification of trucks and the use of cleaner diesel construction equipment. In addition, we were able, through modelling, to explore the impact of shipping distribution centers, an emerging and growing source of diesel emissions within cities in an era of on-line shopping. Validated modeling can improve understanding of the drivers of elevated levels of diesel particulate level as well as identify potential mitigation strategies.Keywords: Air pollution, diesel emissions, diesel particulate matter, air pollution monitoring, air pollution modeling