bluuebunny/crossref_metadata_2025 huggingface dataset:
Transfer standard sensors for disseminating traceable calibrations to the field
Authors: Barham Richard , Rodrigues Dominque , Larsonnier Franck , Schwardt Michaela , Ford Ben , Malcher Freya
Published: February 2023

Transfer standards have an important role in calibration, in enabling traceability to be transferred across calibration facilities or physical locations. It is often the case in laboratory calibration, that the sensors best suited to achieving the optimum calibration accuracy, or measurement uncertainty, have different characteristics to those that need to be deployed in the field. Laboratory calibration techniques are often tailored to work with sensors of a specific type or form factor, and requirements on ruggedness and tolerance of a wide range of environmental conditions are usually of lesser importance under laboratory conditions. Conversely, a transfer standard is ideally suited to both laboratory and field environments. The Infra-AUV project is developing a complete calibration-chain solution to establish measurement traceability for IMS measurements, and consideration has therefore been given to the specification of suitable transfer standard sensors. The thought process behind this, and the infrasound sensors, hydrophones and seismometers ultimately proposed for designation as transfer standards will be presented, together with some characteristic calibration data.
Fiducial Reference Measurements for Soil Moisture (FRM4SM): Toward a better understanding of (satellite) soil moisture uncertainties
Authors: Gibon François , Boresch Alexander , Himmelbauer Irene , Aberer Daniel , Crapolicchio Raffaele , Díez-García Raúl , Dorigo Wouter , Goryl Philippe , Gruber Alexander , Kerr Yann , Mialon Arnaud , Preimesberger Wolfgang , Richaume Philippe , Rodriguez-Fernandez Nemesio , Sabia Roberto , Scipal Klaus , Stradiotti Pietro , Tercjak Monika
Published: February 2023

The aim of this presentation is to report on recent advances concerning the satellite based soil moisture validation done through the ESA project “Fiducial Reference Measurement for Soil Moisture (FRM4SM)”. The main objective of this two years project (May 2021 - May 2023) is to study the means to inform on the confidence in soil moisture data products for the whole duration of a satellite mission. Composed of three international partners (AWST, CESBIO and TU WIEN), it aims at the identification and creation of standards for independent, fully characterized, accurate and traceable (i.e., fiducial) in situ soil moisture reference measurements with corresponding independent validation methods and uncertainty estimations for a satellite mission. The ground reference data is drawn from the International Soil Moisture Network (ISMN). New quality indicators are created to better characterize the aptness of ISMN measurements for satellite soil moisture validation, and protocols provided to identify a select set of fiducial reference data. The satellite part, in charge of independent validation methods, focuses efforts towards the Soil Moisture Ocean Salinity (SMOS) mission from ESA. Finally, the easy-to-use interface for the comparison of satellite soil moisture data against land surface models and in situ data, the Quality Assurance for Soil Moisture (QA4SM), targets to implement all created FRM protocols from ground measurement to validation methods created within the FRM4SM project. 
Mapping regional variability of reservoir temperatures for hydrothermal use: a statistical model based on parameter uncertainty
Authors: Schölderle Felix , Zosseder Kai
Published: February 2023

Forecasting of downhole temperatures is of great interest for the development of deep geothermal energy, since the maximum production temperatures are important for the efficiency of the system. The production temperatures are mainly determined by the prevailing reservoir temperature, which is insufficiently known even in well-developed reservoirs. Most available temperature data from hydrothermal reservoirs are “bottom hole temperatures” (BHTs) that are usually measured during geophysical measurement programs, after each section of a deep geothermal well has been drilled. These measured temperatures are thermally disturbed by the preceding drilling fluid circulation and therefore show a high deviation from the undisturbed formation temperature, requiring correction of the BHT measurements. This is made possible by a variety of analytical and numerical BHT correction methods, all of which require different input parameters for each method. Those parameters are often documented with poor quality, incompletely, or not at all. It can be assumed that the inaccuracy of a corrected BHT value depends to a high degree on the errors of the input parameters and the choice of the correction method is secondary in this respect.In order to perform a complete evaluation of corrected BHT values and to determine the range of errors, we corrected BHT values from over 300 current geothermal and old hydrocarbon wells in the Bavarian Molasse Basin in Southern Germany using a Monte Carlo approach. Thus, the corrected temperature was given as a density distribution rather than a discrete value after individual estimation of the error in the input parameters. This allows a prediction of the formation temperature based on risk scenarios, for example specifying a p10 or p90 case.From the corrected temperatures and taking into account the individual variances studied (p10 and p90 values); we created a set of temperature gradients that take into consideration, if known, the discovered inflow zones and the slope changes in the stratigraphic layers. This approach provides a spatial representation of temperatures while accounting for error propagation by estimates in the correction process, as well as the extrapolation of point temperature data to gradients and the application of geo-statistical methods.
A multi-objective approach for calibrating the FLEXG model to improve glacio-hydrological modelling
Authors: Mohammadi Babak , Gao Hongkai , Feng Zijing , Pilesjö Petter , Duan Zheng
Published: February 2023

Hydrological models as common simulation tools for water resources management play a key role in improving our understanding of hydrological processes on the catchment and global scales. The reliability of hydrological simulations depends on the model structure, the quality of input data, and the calibration of model parameters. A large number of model parameters and interactions among each hydrological variable increase the complexity of the model calibration. Multi-objective model calibration is beneficial to reduce hydrological modeling uncertainty by different calibration criteria, which can lead to more realistic simulations. The FLEXG model is a conceptual glacio-hydrological model within the flexible modeling framework. The FLEXG model considers the effects of topography on the spatial distribution of temperature, precipitation, and runoff generation to have a better understanding of the impacts of landscape on hydrological processes. The FLEXG can simulate various glacio-hydrological variables such as runoff from different sources (e.g. snow and glacier melt), glacier mass balance, snow cover area, and snow water equivalent. This study aims to evaluate the influences of several calibration strategies on the FLEXG model's performance in simulating simulated runoff, snow cover area, glacier mass balance, and snow water equivalent in a glacierized catchment in Sweden. To this end, the FLEXG model was calibrated based on remotely sensed snow cover area data and compared to the traditional calibration strategy (calibrating merely against gauged streamflow data). The FLEXG model was also calibrated based on both gauged streamflow data and satellite snow cover area data as a multi-objective calibration. Glacio-hydrological simulations from the FLEXG model using different calibration strategies were evaluated with multiple metrics and at different temporal scales. Results showed that calibrating the FLEXG using only one variable (runoff or snow cover area) can provide acceptable results for only one variable, while the multi-objective calibration strategy can have acceptable simulation for both runoff and snow cover area. In addition, calibrating the FLEXG model using only snow cover area may underestimate runoff simulation.
Tungsten isotopes and the early evolution of the Moon
Authors: Kruijer Thomas , Archer Gregory , Kleine Thorsten
Published: February 2023

Key events in the early history of the Moon include its formation by a giant impact, the solidification of the lunar magma ocean, and late accretion. The 182Hf-182W system (t1/2 ~9 Ma) constitutes a versatile tool to study each of these processes because they can all result in measurable 182W variations. Here we review the 182W record of lunar rocks and highlight key constraints on the early evolution of the Moon. Tungsten isotope studies on lunar samples demonstrate that there are no resolvable 182W variations within the Moon, implying that lunar magma ocean differentiation later than ~70 Ma after Solar System formation. Nevertheless, the Moon is characterized by a uniform ~25 parts-per-million 182W excess over the present-day bulk silicate Earth (BSE). One possibility is that this 182W difference is radiogenic in origin, in which case the Hf-W system can potentially be used to date the formation of the Moon. However, this interpretation is problematic for two reasons. First, mixing processes during the giant impact very likely modified the 182W composition of the Moon and led to distinct initial 182W compositions of the Moon and Earth. Second, the pre-late accretion 182W compositions of the Moon and BSE overlap within uncertainty, and hence there is no resolved radiogenic 182W difference between the BSE and the Moon. Consequently, the Hf-W system does not provide reliable constraints on the age of the Moon. Instead, the Hf–W systematics are fully consistent with 'young' ages of the Moon, well after the effective lifetime of 182Hf.
Modelling snow interception in a spruce forest in varying climate
Authors: Míka Dominik , Jeníček Michal
Published: February 2023

Spatial and seasonal distribution of runoff in mountain catchments is largely influenced by snow. Therefore, snow storage is an important component of every hydrological model simulating runoff from mountainous catchments. Besides snow cover on the ground, snow storage includes also snow interception, a certain amount of snow captured by vegetation on its canopies. Generally, snow interception is an important part of the hydrological balance in forested catchments. This study builds on results of a snow interception model applied for six consecutive winter seasons 2016-2022 in the Vydra catchment, an experimental research catchment of the Charles University located in the Bohemian Forest, Czechia. The model was validated against measured snow depth and snow water equivalent data in the forest (dominant species Picea abies) and in adjacent open area. Field research has been carried out at the research site to describe the canopy structure of the spruce forest using hemispherical images. The vegetation characteristics were essential for modelling of the snow interception. The mean Leaf Area Index (LAI) calculated from the hemispherical images at the study plot reached 2.34 with the respective canopy closure equal to 86.16%. The LAI values ranged from 2.03 to 2.72 representing the range of canopy closure from 83.6 to 90.2%. These values were further used for calculation of seasonal cumulative snow interception at the study plot for the selected period. The snow interception reached from 68.2 to 105.3 mm in individual years which represent from 31 to 49% of the total seasonal snowfall. The snow interception efficiency differed in every winter season, reflecting the varying weather conditions during seasons and different extremity of snowfall events. Overall, the results of snow interception model is promising and will be further use to improve runoff simulation in experimental catchment.
Estimating exposure biases in early instrumental land surface temperature data
Authors: Wallis Emily , Osborn Timothy , Taylor Michael
Published: February 2023

Exposure biases are non-climatic changes in the surface air temperature record which were introduced due to changes in the way thermometers were protected from solar radiation. The possible presence of the exposure bias in early instrumental temperature datasets is a well-known issue, and the impact of changing thermometer exposures, particularly the transition between historic exposures and the Stevenson screen, has been explored by previous studies. However, despite this, very few adjustments have been made to account for the bias, with the exception of a handful of localised studies. As a result, the exposure bias still accounts for significant uncertainty in global surface air temperature compilations, such as HadCRUT5.In this work we report an attempt to address the exposure bias for extratropical weather stations in a version of CRUTEM5 that has been extended back in time to 1781 (CRUTEM5_ext). We developed statistical models to predict the bias introduced by transitions from four main categories of historic exposure – open, wall-mounted, intermediate and closed – to the Stevenson screen. The models are based on an empirical analysis of the characteristics of the exposure bias observed in 20 parallel measurement studies, together with the temperature and radiation variables that were a priori expected to influence the magnitude of the bias in mean temperatures on a monthly timescale. Separately, we have compiled a database detailing the historic exposures in use at stations and the timing (or approximate timing when a precise time is not known) of the transition to the Stevenson screen. The statistical models, where robust, are then applied to the individual stations within CRUTEM5_ext to make adjustments for the exposure changes according to the database of historic exposures.This presentation will outline the model development, give a brief overview of the evolution of thermometer exposures in use in the early instrumental period for extratropical stations, and will illustrate the impact the exposure bias adjustments have on the CRUTEM5_ext data. This work forms part of the NERC-funded GloSAT project (https://www.glosat.org/) which is developing a global surface air temperature dataset starting in 1781. Where appropriate, stations used to create the GloSAT dataset will be adjusted for the exposure bias using the models presented here. 
From shoreface to riverbed – Facies evolution in Burdigalian deposits of the North Alpine Foreland Basin
Authors: Drießle Tim , Hofmayer Felix
Published: February 2023

During the Burdigalian the North Alpine Foreland Basin, as part of the central and western Paratethys, underwent various paleogeographic and paleoenvironmental changes which led to the deposition of different sedimentary facies. For instance, the Ottnangian regional stratigraphic stage (18.2 – 17.3 Ma) was characterized by a major transgression in the beginning, with the deposition of several littoral facies along the northern coastline of the North Alpine Foreland Basin. Successively, the late Ottnangian documents the final retreat of the Paratethys Sea from the North Alpine Foreland Basin and the deposition of widely distributed fluviatile units. The outcrop Neustift in southeast Germany bears many different siliciclastic facies and shows the transition of the Ottnangian marine realm towards a riverine-deltaic environment. Despite the exceptional size and complexity of the succession, this outcrop is only poorly studied. Anyhow, this section gives unique potential for the understanding of the facies evolution during the terminal Ottnangian. In total a 70 m long and 15 m high sedimentary log was recorded together with several micropaleontological samples (1 kg each) for the reconstruction of the depositional environment and stratigraphic positioning. The micropaleontological samples yielded 164 genera of benthic foraminifera and 144 species of ostracods. Moreover, these deposits are extremely rich in macrofossils (elasmobranchia, mollusca, brachiopoda, echinoidea) which are also poorly studied. We found out, that the lowermost segment of the section belongs to the marine “Littoral Facies of Holzbach-Höch”, which deposited directly on top of a transgressive layer on the crystalline basement. Several of the observed ostracod species are new to these deposits. Large-scale cross-bedding structures show that this shallow marine environment was affected by strong tidal currents along the rocky shoreline. The fine-grained sediments with wavy and lenticular bedding on top of the littoral deposits show an ongoing transgression, with neritic foraminiferal assemblages and bioturbation. They were assigned by biostratigraphy to the uppermost Neuhofen Formation. Finally, the marine deposition is replaced by a large-scale deltaic system, resulting into the deposition of the fluviatile Ortenburg gravel. This preliminary study should draw some more attention to this unique outcrop in the North Alpine Foreland Basin and the potential for further studies in the realm of sedimentology and paleontology. 
Role of variable plate kinematics history in the back-arc deformation regime along the western Pacific margin (Japan Sea)
Authors: Ficini Eleonora , Cuffaro Marco , Gerya Taras , Doglioni Carlo
Published: February 2023

Extension at back-arc basins generally occurs behind arc-trench systems and the mechanisms which act at its origin, as well as the deformation regime developed, are strongly related to the subduction of oceanic lithosphere. Here, we examine the Japan Sea back-arc basin evolution using numerical simulations along the western margin of the Pacific plate, where the subduction processes have been responsible for the deformation style during the last 57 Ma. We carried out 2D high-resolution thermo-mechanical numerical models of subduction dynamics in this area, increasing the simulation complexity integrating into the computations i) the kinematic variability of the Pacific plate over the geological past with respect to a fixed Eurasia, ii) a Low-Viscosity Zone within the asthenosphere, iii) a horizontal eastward mantle flow. Our results show a main kinematic control of the subduction trench position, which advances and retreats in time, providing stages of compression and extension in the Japan Sea back-arc basin. The obtained deformation regime is comparable with the tectonic evolution history occurred along the Eastern Eurasian margin and with analyses on paleo-volcanic front position and paleo-stress reconstructions in the Japan Sea area.
Solar Wind Impact on ENAs from Earth’s Subsolar Magnetosheath
Authors: Starkey Michael J. , Dayeh Maher A. , Fuselier Stephen A. , Petrinec Steven M. , McComas David J. , Ogasawara Keiichi , Szalay Jamey R. , Schwadron Nathan A. , Sokół Justyna M.
Published: February 2023

The solar wind is heated and decelerated by Earth’s bow shock, resulting in a hot and dense population of magnetosheath ions. This increases the production of energetic neutral atoms (ENAs) in this region, which enables the global imaging of Earth’s magnetosheath using ENA imagers onboard the IBEX spacecraft. Furthermore, since these ENAs are unaffected by electromagnetic forces, they carry information about the inherent properties of the progenitor plasma.        In this work, ENA fluxes from the subsolar magnetosheath, observed by the IBEX spacecraft, are compared to solar wind (SW) conditions. These comparisons reveal that the flux of ENAs is strongly influenced by the SW density, speed, and temperature. Furthermore, evidence of the specularly reflected proton population in the magnetosheath is observed by comparing ENA spectra for different interplanetary magnetic field configurations. This work provides observational constraints to modeling and theoretical work on ENAs from Earth's subsolar magnetosheath and shows that ENAs from Earth's magnetosheath are reflective of their parent ion populations in the magnetosheath.
On flow decomposition in realistic ocean models
Authors: Rosenau Silvano , Chouksey Manita , Eden Carsten
Published: February 2023

Oceanic flow comprises of a fast and a slow evolving component. Decomposing the flow field into these components is necessary to understand processes like mesoscale eddy dissipation and spontaneous wave emission. These processes are potentially important wave sources and lead to an energy transfer between the slow and the fast component. The first order approach is to decompose in geostrophic and non-geostrophic components. Since a part of the non-geostrophic component evolves slowly due to nonlinear interactions between both component, this approach is not precise enough to quantify energy transfers. To obtain higher accuracy in decomposing the flow field, more precise methods are required, such as optimal balance or nonlinear normal mode decomposition. However, their application is limited to idealized model settings that neither include topography nor a varying Coriolis parameter. Here, we modified the optimal balance method with a time averaging procedure, such that it is applicable in more realistic ocean models. We compared the new modified method with existing methods in a shallow water model and in a non-hydrostatic model. For longer time averaging periods, the modified optimal balance method converges against the original method.
Ray-tracing global gravity wave observations in 21 years of AIRS data
Authors: Noble Phoebe , Wright Corwin , Hindley Neil , Moffat-Griffin Tracy
Published: February 2023

Gravity waves have a variety of different sources including wind flow over mountains, convection and jet stream instabilities. Yet when working with observations of gravity waves we can only make informed guesses of their sources. In this work we use GROGRAT to backwards ray trace stratospheric observations of gravity waves globally to learn more about their origins.We use observations of temperatures at 40km altitude observed by the AIRS (Atmospheric InfraRed Sounder) instrument on NASA’s Aqua satellite. From these observations we extract temperature perturbations and use the 3D Stockwell transform to derive gravity wave properties such as momentum flux, horizontal wavelength, vertical wavelength. These gravity waves are then backwards ray traced through the ERA5 atmosphere. The significance in this work lies in the volume: we ray trace 21 years (2002-2022) of AIRS data globally, representing by far the largest such observational dataset ever reverse ray-traced.By investigating the lowest traceable altitude of these rays, we can attribute the gravity waves to their sources (orographic gravity waves will originate near the surface whilst convective waves will have a higher origin). We can also investigate the horizontal propagation of orographic gravity waves from specific mountain ranges and how this changes seasonally. This work aims to answer the question: “Where do gravity waves observed by AIRS come from?”
Crystalline silica polymorph surfaces and nearly free silanols: occurrence and possible role in toxicity mechanisms
Authors: Bellomo Chiara , Escolano-Casado Guillermo , Cananà Stefania , Tomatis Maura , Leinardi Riccardo , Mino Lorenzo , Turci Francesco , Pavan Cristina
Published: February 2023

Crystalline silica (CS) is a well-known toxic particle that may cause severe pathologies including silicosis, lung cancer, and several autoimmune diseases. [1a,b] The hazard associated to crystalline silica is extremely variable and depends on some specific characteristics, including crystal structure and surface chemistry.[1c] In particular, a specific family of surface silanols, called nearly free silanols (NFS), has been recently related to the interaction mechanisms occurring between quartz particles and cell membrane components, which initiate the lung inflammatory reaction. [2] Even though this phenomenon has been studied for decades on quartz,  the research on other silica polymorphs was limited, also because of the relative low abundance of some polymorphs. The CS polymorphs, i.e., quartz, cristobalite, tridymite, coesite, and stishovite, share the SiO2 stoichiometry and differentiate for crystal structure. [3] Thus, the different crystal lattices expose differently ordered hydroxyl group patterns at the crystal surface. We proved that the NFS occur and take part in the molecular bio-interactions, not only on quartz, but also on the other CS polymorphs. Five high-purity samples representative of the five CS polymorphs were fully characterized by XRPD, Scanning Electron Microscopy, and IR spectroscopy. When CS polymorphs were contacted with model membranes (red blood cells), all of them were able to disrupt cell membranes, except stishovite, which was the only polymorph without NFS. By thermally modulating the topochemistry of surface silanols, it was possible to show that the membranolytic activity of the CS polymorphs quantitatively paralleled the occurrence of NFS. This observations confirmed the central role of NFS in regulating the interaction of silica with biomembranes. In conclusion, these results put the surface characteristics of CS particles in the foreground with respect to the crystal habit and provide a comprehensive understanding of the molecular mechanisms associated with silica hazard and bio-minero-chemical interfacial phenomena. [4][1] a) KAWASAKI, H. 2015, Inhal Toxicol, 27, 363-77; b) IARC 2012, IARC monographs on the evaluation of carcinogenic risks to humans, Lyon, World Health 543 Organisation c). BORM, P. J. A., et al. 2018, Part. Fibre. Toxicol., 15, 23;[2] PAVAN, C., et al., 2020, Proc Natl Acad Sci U S A, 117, 27836-27846.[3] GUTHRIE, G. D. & HEANEY, P. J. 1995, Scand J Work Environ Health, 21 Suppl 2, 5-8.[4] PAVAN. C., et al., 2023, accepted on Frontiers in Chemistry, DOI: 10.3389/fchem.2022.1092221.
Monitoring the impact of rain-on-snow events across the Arctic with satellite data
Authors: Bartsch Annett , Bergstedt Helena , Muri Xaver , Rautiainen Kimmo , Leppänen Leena , Joly Kyle , Sokolov Aleksandr , Orekhov Pavel , Ehrich Dorothee , Soininen Eeva Marietta
Published: February 2023

Rain-on-Snow (ROS) events change snow pack properties and in extreme cases ice layers form which affect wildlife, vegetation and soils beyond the duration of the event. Active as well as passive microwave sensors have been used in the past to document ROS on regional scale. Either wet snow during a ROS event or the formation of crust afterwards are identified in most cases. The fusion of both approaches is promising for circumpolar monitoring.C-band radar is of special interest due to good data availability including a range of nominal spatial resolution (10 m–12.5 km). Previous studies indicated that radar backscatter is suitable to identify snow structure change. As an example L-band passive microwave observations from SMOS and C-band backscatter from Metop ASCAT have been jointly analysed and compared to snowpit observations in Scandinavia and Northwestern Siberia.A circumpolar dataset of potential ROS has been created. The gridded information has been eventually aggregated for events. Larger mid-winter events have been eventually extracted for 2012-2021. They occur mostly in the NE part of northern Eurasia (mostly November) and across Alaska (mostly December). The spatiotemporal patters of these events and the magnitude of snow structure change will be presented and discussed.
On the effect of vibration on dry/fluid-saturated granular flows: Implications for geological hazards induced by earthquakes
Authors: Wang Yuhan , Mao Wuwei , Rafn Heimisson Elías
Published: February 2023

Vibrating boundaries are widely encountered, for example, between soil and bedrock during earthquake shaking. We understand that vibration of such boundaries can lead to instabilities in granular media with many applications to geological hazards, such as liquefaction and landslides, and during geological engineering applications. Although numerous studies have been dedicated to revealing the behavior of granular flows under various flowing regimes, the significance of vibrating boundaries remains an open problem. To fill this gap, we introduce a vibrating base boundary into the collapse of a granular column with a numerical scheme. To understand the role of fluids, we contrast the behavior of granular flows under dry and fluid-saturated conditions. From the simulations, the development of anisotropy in spatial inter-grain contact force distribution is studied. The fluid-saturated condition is achieved via a two-way coupled CFD-DEM method. From these simulations, a scaling law of granular flow is derived for vibrating boundaries. We illustrate for the first time the energy evolution of the granular system with vibrating boundaries. This work demonstrates the role of vibration in increasing the runout distance and the maximum kinetic energy of granular flows, this suggests a link between the mesoscale inter-grain responses and macro-scale dynamics of granular geological hazards triggered by earthquakes. Additionally, the spatial distribution of inter-grain contact forces is presented under dry and fluid-saturated conditions to indicate the anisotropic development inside the granular assembly.
Seasonal forecasts of the nighttime heat waves in Europe
Authors: Torralba Verónica , Materia Stefano , Cavicchia Leone , Álvarez-Castro M.Carmen , Scoccimarro Enrico , Gualdi Silvio
Published: February 2023

Extreme climate events such as heat waves cause enormous stress on human health and ecosystems and economic losses in agriculture, energy, or water management activities. In particular, the combined effect of above-normal nighttime temperatures and high humidity poses a high risk to human health. This is related to the thermal discomfort which prevents the human body’s recovery from daytime high-heat exposure. Seasonal forecasts of the nighttime heat waves might be used as a tool to anticipate these risks and to better manage their social and economic impacts. However, the ability of the seasonal forecast systems to predict these extreme events has not been explored so far. This work provides insight into the potential of four seasonal forecasting systems (CMCC Seasonal Prediction System 3.5, DWD System 2.1, ECMWF SEAS5, and Météo-France System 7) to provide skillful and reliable predictions of the nighttime heat waves in Europe during the boreal summer season. Different potential proxies for the assessment of nighttime heat waves have been considered: nighttime apparent temperature computed from temperature and humidity at night, the temperature at night, or daily minimum temperature. There are different indices that can be used to investigate extreme temperatures, but the one chosen in this study is very suitable for seasonal forecast analysis because it is invariant to the mean biases and provides an integrated view of the nighttime heat waves for the entire season with information on their duration, frequency, and intensity. The forecast quality assessment has revealed that state-of-the-art seasonal forecast systems are able to provide useful information on the nighttime heat waves in Southern Europe, which is a particularly vulnerable region where timely climate information can benefit the decision-making processes. 
Atmospheric Circulations and Drought Conditions in British Catchments: Highlighting the Role of the East Atlantic Pattern
Authors: West Harry , Quinn Nevil , Horswell Michael
Published: February 2023

Drought events are influenced by a combination of both climatic and local catchment characteristics. In Great Britain the North Atlantic Oscillation (NAO) has long been recognised as the leading mode of climate variability, and studies have also noted the role of the East Atlantic Pattern (EA) as a secondary mode. This study aimed to develop an understanding of the combined influence of the NAO and EA on rainfall distribution and magnitude and the variable nature of meteorological to hydrological drought propagation. Initially, this study explores correlations between teleconnection indices and standardised precipitation and streamflow indices for 291 catchments across Great Britain, before focusing on nine case study catchments for further analysis. For each case study catchment, we use quantile regression and an analysis of drought frequency to explore the combined influence of the NAO and EA on drought conditions.Through a convergence of evidence from these analyses we make three observations. Firstly, in the winter months both the NAO and EA exert an influence on drought conditions, however there is spatial variability in the relative influence of the NAO and EA; the NAO has a stronger influence in the north-west, whilst the EA has a stronger influence in the southern and central regions. Secondly, in the summer months, less distinctive spatial differences were found, with higher probability of drought conditions under NAO+ phases, which however can be enhanced or moderated by the EA. Finally, as a result of catchment characteristics there is spatio-temporal variability in the propagation of meteorological to hydrological drought. Our findings suggest that by considering the NAO and EA in combination, we can better describe climate and drought variability. We conclude by noting the potential implications our study has on the role of monthly teleconnection forecasts in water management decision making in Great Britain, and acknowledge the current limitations associated with incorporating such understanding.
On the accurate simulation of hydrological droughts in Alpine regions: investigating the multiple role of rainfall-runoff model dynamics and basin characteristics
Authors: Neri Mattia , Toth Elena
Published: February 2023

The reliability of rainfall-runoff models in reproducing hydrological drought events is of primary importance for multiple applications (e.g. water resource management or agricultural risk assessment), especially in a context of expected future water scarcity. Typical model performance metrics are often not enough to assess the accuracy in the simulation of droughts. In fact, it is necessary to consider drought-specific indices taking into account, e.g., low flow characteristics, duration and deficit volumes as well as their seasonality and timing. Understanding which hydrological processes are (or are not) adequately modeled and why, in respect to such drought-specific performances, allows to assess the strengths and weaknesses of each model and may provide guidance on how to improve model set-up and its reliability.Through the application of a conceptual semi-distributed model on a set of Alpine basins, the aim of this preliminary work is to analyse the relationship between drought-specific performance metrics, basin characteristics and model parameters. In particular, the specific influence of the different model state variables (e.g. snow water equivalent, evapotranspiration and soil moisture) on the reproduction of drought events is investigated.The model used is a semi-distributed modelling framework based on the airGR rainfall-runoff models (Coron et al. 2017), applied through the R package airGRiwr (Dorchies 2022). The case study is a set of Alpine catchments, characterised by a high degree of “nestdness” which allows to fully implement the semi-distributed model structure and to perform its diagnosis.The major advantage of a semi-distributed model, if properly set-up, is its ability to differentiate hydrological dynamics between the sub-catchments. In mountainous basins, for instance, simulating in a separate way the upstream headwater sub-catchments may substantially improve the accuracy in the simulation of snow storage and melting, which strongly affect the occurrence and timing of drought events. For this reason, the work will also analyse the benefits of an increasing spatial resolution of the semi-distributed set-up of the model, comparing the outcomes obtained when sequentially calibrating the model in a semi-distributed fashion on the upstream sub-catchments in respect to the baseline of a lumped configuration. ReferencesCoron, L., Thirel, G., Delaigue, O., Perrin, C. and Andréassian, V. (2017). The Suite of Lumped GR Hydrological Models in an R package. Environmental Modelling and Software, 94, 166-171, doi: 10.1016/j.envsoft.2017.05.002.David Dorchies (2022). airGRiwrm: 'airGR' Integrated Water Resource Management. R package version 0.6.1. https://CRAN.R-project.org/package=airGRiwrm
ONERA accelerometers for future gravity mission
Authors: Liorzou Françoise , Lebat Vincent , Christophe Bruno , Boulanger Damien , Rodrigues Manuel , Zahzam Nassim , Bidel Yannick , Bresson Alexandre
Published: February 2023

The 2017-2027 Decadal Survey for Earth Science and Applications from Space has identified the Targeted Mass Change Observable as one of 5 Designated Mission. In Europe, ESA has proposed to Ministerial Counsel of November 2019 to begin a Phase A on the Next Generation Gravity Mission.These missions will continue the observation provided by GRACE and GRACE-FO. In these missions and the future concepts, the accelerometer provides either the gravity signal in a gradiometer configuration (GOCE type mission), or the non-gravitational acceleration to be suppressed to the ranging measurement between two satellites (GRACE-type mission).ONERA has procured the accelerometer for all the previous gravity missions (GRACE, GOCE, GRACE-FO) and works to improve the scientific return of the instruments for the future missions.In a frame of a pre-development contract with ESA to increase TRL, Onera is developing its new accelerometer MicroSTAR, a high accuracy accelerometer with 3 sensitive linear acceleration measurements as well as 3 angular acceleration measurements for the attitude control or reconstruction.In parallel, a miniaturized version of MicroSTAR with low accuracy, CubeSTAR accelerometer, is developed with internal funding. CubeSTAR is adapted for constellation or nanosat.An other way is to improve the low-frequency noise of the accelerometer, by hybridization of electrostatic accelerometer with cold atom interferometer.The presentation will detail these developments.
Evaluating soil structure and biological activity in soil cores under different management systems
Authors: Leuther Frederic , Fischer Dorte , Nunan Naoise , Herrmann Anke
Published: February 2023

Soil structure is a key feature in controlling microbial access to organic matter in soils. The spatial arrangement of solids and pores in agricultural soils is shaped by the used tillage and crop system. However, spatial heterogeneities make it difficult to determine relationships between soil biology and soil structure, and often homogenized, sieved soils are used to evaluate organic matter turnover in soils. In this study, we used heat dissipation as an indicator for biological activity in soils taken from two different tillage systems (conventional vs. reduced tillage) and two different cropping systems (crop rotations with either maize or winter wheat as main crop) running for 12 years. In order to evaluate the impact of soil structure, we investigated the response of both repacked and undisturbed soil cores (3 cm in height, 2.7 cm in diameter) to water and glucose addition. Pore structure indicators and particulate organic matter content were quantified by X-ray computer tomography at a resolution of 15 µm.We will show that calorimetry is a suitable tool to monitor the biodegradation of C sources in undisturbed soil cores and that both tillage system and crop rotation effect biological activity in soil. In summary, soil under maize cultivation dissipated more heat compared to the wheat crop rotation. In both, repacked and undisturbed samples, conventional tillage promoted heat dissipation in response to water addition, likely due to the annual incorporation of labile organic matter. However, structural and organic matter indicators could only explain the variance in heat dissipation to some extent. Thus, the usage of undisturbed soil cores provides new challenges to evaluate the link between soil structure and microbial activity due to increased variability.
Determining the wave-slope statistics using IASI observations of the sea surface
Authors: Guérin Charles-Antoine , Capelle Virginie , Hartmann Jean-Michel
Published: February 2023

The sea-surface slope probability is an important physical parameter to describe the ocean surface and its interaction with the atmosphere. Its reference measurement dates back to the celebrated airborne experiment conducted by Cox and Munk (CM) in 1951 using sun glitter patterns. The obtained two-dimensional slope distribution function deviates slightly from the Gaussian distribution with pronounced up-to-crosswind and up-to-downwind asymmetries, a stronger peakedness and a slower decay at large values. It is classically parametrized by a Gram-Charlier representation with seven directional parameters describing the mean square slopes (MSSs) as well as the skewness and kurtosis coefficients for wind speeds up to 15 m/s. The MSSs are shown to follow a quasi-linear trend with wind speed, a result which has been confirmed by many subsequent airborne and spaceborne optical measurements and wave-tank experiments. The higher-order statistical coefficients have a non trivial dependence on wind speed as shown by the more recent results by Bréon and Henriot (2006); however, they are challenging to evaluate accurately and suffer from a larger uncertainty. We re-examine the sea-surface probability by using radiances collected from space by the Infrared Atmospheric Sounder Interferometer (IASI) when looking down at ocean surface during the day. This is achieved by using about 300 channels between 3.6 and 4.0 μm and a physically-based approach which properly takes the contribution of the reflected solar radiation into account. This unique data set covers 13 years of observations over the world ocean, resulting in about 150 millions IASI appropriate spectra and as many wave-slope probabilities. Based on these experimental wave-slopes we revisit and discuss CM results and methodology and their limitations. We propose an original and robust approach for accurate retrievals of the Gram-Charlier parameters. Our findings for the MSSs are fully compatible with those of CM but our lower uncertainties enable to point out departures from the linear wind-speed dependencies and a slight overestimation of the upwind MSS described by the linear fit of CM at moderate wind speed. Our skewness and kurtosis coefficients show clear influences of the wind speed, with a steady decrease of the former and the alongwind kurtosis coefficient being maximal at moderate wind speeds, features that CM could not point out due to the limitations of their measurements. We revisit the renormalization procedure employed by CM to obtain the complete variances from truncated pdfs and show that it imposes stringent conditions on the kurtosis coefficients that allow to determine them accurately. We also provide measurements of the shifted position of the most probable slope as well as a demonstration of a qualitative change of regime in the updown wind asymmetry of the wave-slope probability when the wind speed increases.
The mixed layer depth in Ocean Model Intercomparison Project (OMIP) high resolution models
Authors: Tréguier Anne Marie , de Boyer Montégut Clement , Chassignet Eric , Fox-Kemper Baylor , Hogg Andy , Iovino Doroteaciro , Kiss Andrew , le Sommer Julien , Lique Camille , Lin Pengfei , Liu Hailong , Serazin Guillaume , Sidorenko Dmitry , Yeager Steve , Wang Qiang
Published: February 2023

The ocean mixed layer is the interface between the ocean interior and the atmosphere or sea ice, and plays a key role in climate variability. Numerical models used in climate studies should therefore have a good representation of the mixed layer, especially its depth (MLD). Here we use simulations from the Ocean Model Intercomparison Project (OMIP), which have been forced by a common atmospheric state, to assess the realism of the simulated MLDs. For model validation, an updated MLD dataset has been computed from observations using the fixed density threshold recommended by the OMIP protocol. We evaluate the influence of horizontal resolution by using six pairs of simulations, non-eddying (typically 1° resolution) and eddy-rich (1/10° to 1/16° resolution). In winter, low resolution models exhibit large biases in the deep water formation regions. These biases are reduced in eddy-rich models but not uniformly across models and regions. The improvement is most noticeable in the mode water formation regions of the northern hemisphere, where the eddy-rich models produce a more robust MLD and deep biases are reduced. The Southern Ocean offers a more contrasted view, with biases of either sign remaining at high resolution. In eddy-rich models, mesoscale eddies control the spatial variability of MLD in winter. Contrary to an hypothesis that the deepening of the MLD in anticyclones would make the MLD deeper globally, eddy-rich models tend to have a shallower MLD in the zonal mean. In summer, a deep MLD bias is found in all the non-eddying models north of the equator; this bias is greatly reduced at high resolution. In addition, our study highlights the sensitivity of the MLD computation to choice of a reference level and the spatio-temporal sampling, which motivates new recommendations for MLD computation in future model intercomparison projects.
Determination of geometrical parameters of fractures in Triassic dolomites: the case study of the Daruvar Hydrothermal System (Croatia)
Authors: Kosović Ivan , Pola Marco , Matoš Bojan , Pavičić Ivica , Frangen Tihomir , Pavić Mirja , Mileusnić Morena , Borović Staša
Published: February 2023

Carbonates extend on approximately 15% of the ice-free land surface, and approximately 16% of the global population lives in karst areas depending on its groundwater resources. The estimation of the permeability field in carbonate aquifers is crucial for their sustainable management. The presented research was conducted in the Daruvar hydrothermal system (DHS) in the north-eastern part of the Republic of Croatia. It is a typical hydrothermal system hosted in carbonate rocks with water temperatures up to 50 °C. DHS includes both the thermal spring area in the Daruvar area and the western slopes of Mt. Papuk, which are predominantly built of the Mesozoic carbonate rock complexes and represent the recharge area of the thermal system. The objectives of the research are: i) the geometric reconstruction of discontinuities that drive the fluid flow, and ii) the estimation of the hydrogeological parameters of the carbonate thermal aquifer using structural, photogrammetric, and hydrogeological approaches. The regional structural setting was analysed through field investigations evidencing the occurrence of a polyphase deformation. In particular, NNE-SSW compression and ESE-WNW extension were identified, which are consistent with the deformation phases of the Pannonian Basin. Outcrop analogues of the carbonates constituting the thermal aquifer and affected by comparable multi-phase deformation of the rock mass were selected to detail the role of fracture systems on the permeability field. At selected locations, detailed photogrammetric measurements will be carried out and the vectorization of the fractures will be performed for the construction of a virtual outcrop (2D display of fracture traces). The results will be used to evaluate the geometrical parameters of the fractures (e.g., orientation, mean trace length, density, intensity) being the input parameters for discrete fracture network (DFN) modelling. The reconstructed network of discontinuities will be tested through hydrogeological numerical modelling using the DFN approach, thereby enabling the estimation of the hydraulic parameters of the rock mass. The estimated hydraulic parameters will be correlated with the results of pumping tests conducted in the Daruvar area.Acknowledgments: Presented research has been conducted in the scope of the project “Multidisciplinary approach to hydrothermal system modelling” (HyTheC) funded by the Croatian Science Foundation under grant number UIP-2019-04-1218.