bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling forest SOC change – calibration and validation challenges
Authors: Bitunjac Doroteja , Ostrogović Sever Maša Zorana , Merganičová Katarína , Marjanović Hrvoje
Published: February 2023

Soil organic carbon (SOC) is the largest terrestrial carbon (C) pool with a vital role in the global C cycle. Considering it is one of five mandatory pools in national greenhouse gas (GHG) inventory reports, it is important to accurately assess SOC stocks and changes. Measuring SOC stock changes is challenging due to costly and destructive soil sampling, the high spatial variability of soil carbon and the slow process of soil C accumulation or loss. In order to reduce the uncertainty of SOC stock changes estimates, repeated national soil inventory is required. In the absence of repeated national inventories, SOC stock changes could be estimated using a modelling approach. The aim of our research is to calibrate and validate the terrestrial ecosystem model Biome-BGCMuSo for the simulation of SOC stock changes in lowland forests as an additional tool for use in national GHG inventory reporting.In our work, we combine different data sources (chronosequence experiment and eddy-covariance (EC) site) and different data types and frequencies (long-term C stocks and high-frequency C fluxes) of various ecosystem variables (aboveground live wood C (AGC), forest floor C, SOC, Net Ecosystem Exchange (NEE), Gross Primary Productivity (GPP) and Ecosystem Respiration (RECO)). The model calibration was performed using the daily values of main ecosystem C fluxes from the EC tower in the Jastrebarsko pedunculate oak forest and annual data on AGC, forest floor C and SOC from permanent measurement plots in the footprint of the EC tower. For model validation, we used annual data on C stocks in the aboveground live wood biomass, forest floor and mineral soil in the top 30 cm from seven stands of pedunculate oak chronosequence in Jastrebarsko forest. All analyses were performed in R software.  Measured SOC showed no age trend and high between-stand spatial variability of 19-30%, while for modelled SOC between-stand spatial variability was only 6% and a negative age trend was observed. The calibration using solely daily NEE fluxes resulted in a better overall agreement of model output with observations for this variable, but at the cost of the reduction in intra-seasonal variability. The calibration using aboveground and soil C stocks improved the agreement for these variables but caused greater discrepancies between measured and modelled daily NEE fluxes. The model validation showed a good agreement for C stock change in aboveground live wood biomass and mineral soil for most of the chronosequence stands, but with high disagreement between measured and modelled C stocks in the forest floor in general. Obtained results emphasize the importance of multi-variable calibration and validation to improve model accuracy and robustness across all simulated pools, fluxes and processes.
EPOS-GNSS DATA GATEWAY: a portal to European GNSS Data and Metadata
Authors: Vergnolle Mathilde , Menut Jean-Luc
Published: February 2023

EPOS-GNSS is the Thematic Core Service dedicated to GNSS data and products for the European Plate Observing System. EPOS-GNSS provides a service to explore and download validated and quality controlled data and metadata. This service is based on a network of 10 data nodes connected to a centralized portal, called "EPOS-GNSS Data Gateway". The service aims to follow the FAIR principles and continues to evolve to better meet them. It currently provides more than 4 millions of daily files in the RINEX standardized format for 1670 European GNSS stations and their associated metadata. In addition to the integration into the multi-disciplinary EPOS data portal, the service proposes a direct access to the data and metadata for users with a need for more complex or more specific queries and filtering. A GUI (web client) and a specialized command line client are provided to facilitate the exploration and download of the data and metadata. The presentation introduces the EPOS GNSS-Data Gateway (https://gnssdata-epos.oca.eu), its clients, and its use.
Lead time continuous statistical post-processing of ensemble weather forecasts
Authors: Wessel Jakob , Ferro Chris , Kwasniok Frank
Published: February 2023

Numerical weather prediction (NWP) models usually output their forecasts at a multiplicity of different lead times. For example, the Met Office ensemble prediction system for the UK (MOGREPS-UK) predicts atmospheric variables on a 2.2km grid for up 126h on hourly and sub-hourly timesteps. Even though for applications, information is often required on this range of lead times, many post-processing methods in the literature are either applied at fixed lead time or by fitting individual models for each lead time. This is also the case in systems used in practice such as the Met Office IMPROVER system. However, this is 1) computationally expensive because it requires the training of multiple models if users are interested in information at multiple lead times and 2) prohibitive because it restricts the training data used for training post-processing models and the usability of fitted models.In this work we investigate lead time dependence of ensemble post-processing methods by looking at ensemble forecasts in an idealized Lorenz96 system as well as temperature forecast data from the Met Office MOGREPS-UK system. First, we investigate the lead time dependence of estimated model parameters in non-homogenous Gaussian regression (NGR -- a standard ensemble post-processing technique) and find substantial smoothness. Secondly, we look at the usability of models fitted for one lead time and employed at another to then thirdly fit models that are “lead time continuous”, meaning they work for multiple lead times simultaneously by including lead time as a covariate using spline regression. We show that these models can achieve similar performance to the classical “lead time separated” models, whilst saving substantial computation time. Fourthly and finally we make first steps towards the development of a cheap computational model including seasonality and working continuously over the lead time, needing to be fit only once.
The importance of bacterial metabolism contribution to soil organic carbon revealed by Monte Carlo simulations
Authors: Dathe Annette , Lynch Laurel , Woolf Dominic , Lehmann Johannes
Published: February 2023

Soil is the largest terrestrial carbon reservoir and processes leading to carbon sequestration play a crucial role in quantifying size as well as changes of this important pool. Microorganisms transform plant residues to smaller organic compounds, and often necromass is assumed to be the main stable end product. The turnover of microbial biomass at end of life, however, is only one pathway by which microorganisms contribute to soil organic matter. As a proof-of-concept, we use a mechanistic modeling approach with Monte Carlo simulation of 10,000 iterations, where input parameters vary according to values derived from literature. Bacterial growth follows a Monod kinetic, and biomass is further transformed to exudates, waste, and exo-enzymes, which vary in their C:N ratios. Assuming abundant N-resources, bacterial necromass contributes with 23.2% (median) of organic carbon only a minor portion to microbially-derived soil organic matter at the end of the simulation of 72 days. Most of the microbially derived organic carbon originates as part of metabolism by a combination of exudation (median 39.0%), wastes such as for osmotic regulation (median 22.4%), and exoenzyme production (median 10.3%). The organic product yields vary by about 300% between anabolic stages six days after substrate additions compared to catabolic stages at the end of the simulation. Predictions and management of soil organic carbon sequestration should therefore be based on carbon input through microbial metabolism rather than assumptions of carbon input solely at end of life.
Aquatic Aggregates as “Vector” for Microplastics
Authors: Wu Nan , Grieve Stuart , Manning Andrew , Spencer Kate
Published: February 2023

Easily transportable microplastics (plastic particles < 5 mm) have become an increasingly important component of suspended particulate matter (SPM) in the aquatic environment, and their fate is significantly influenced by aggregation and flocculation. Aggregation modifies particle properties (e.g., size) controlling the hydrodynamics of SPM in the aquatic environment. Hence, understanding and quantifying aggregation is key to predicting the behaviour of both SPM and associated microplastics. However, quantifying the aggregation degree of microplastics with complex parameters in various water environments is very difficult.Here, an extensive range of microplastics including 8 polymer types, 3 shapes, different weathering conditions and different sizes (10-300 µm for fragments and microbeads, and 10-1500 µm in length for microfibers, respectively), were used to explore the aggregation dynamics of microplastics. Over 4000 measurements of incorporated microplastics were collected, and we found microplastic size (MinFeret diameter of fragments, diameter of microfibers) is the key parameter to determining the aggregation behavior. Our results simplified the aggregation of microplastics with a wide range of properties in various water ecosystems into two parameters, the size of microplastics and the size of aggregates. A boundary curve for microplastics was fitted based on size relationships between microplastics and aggregates to divide microplastics into aggregable and un-aggregable groups. This study can aid better understanding the fate of microplastics in various aquatic environments at multiple scales.
Early Plant responses to Large Igneous Province Activity: the Devonian of Angarida, Siberia.
Authors: Dowding Elizabeth , Akulov Nikolay , Mashchuk Irina
Published: February 2023

Devonian plants in Siberia present protracted pioneer succession. During the Devonian Angarida was a large and semi-isolated continent within warm, arid zones of the northern hemisphere. Early plants in the Devonian did not originate upon Angarida, instead they are known to migrate to Angarida allowing a unique opportunity to study their changing biogeography and their influence upon the virgin landmass. In the Late Devonian, the Viluy-Yakutsk Large Igneous Province had two active phases and dramatically altered the physical and chemical environment of both the early plants and the marine systems. Our research into the survivourship dynamics of early plant communities upon the palaeocontinent Angarida have demonstrated that transgression and volcanogenic nutrient influx were key to the survival of colonising plants. Taxic proportions show that migrating taxa entered Angarida from the southwest, Kuznetsk and Minusinsk basins, dispersing across the continent in waves through central areas northwards. The patterns of dispersal are consistent throughout the Devonian and into the Early Carboniferous. Increased nutrient load from the active pulses of the Viluy-Yakutsk Large Igneous Province, biogeomorphic ecosystem engineering, and the increased biomass of Angaridan plants are assisted by Late Devonian transgression. These cumulative factors can be linked to the Late Devonian marine extinctions observed in Siberia.
Removing local variability from Potential Gradient data – the Carnegie filter
Authors: Harrison R.Giles , Nicoll Keri , Joshi Manoj , Hawkins Ed
Published: February 2023

Measurements of atmospheric electricity have been made at many sites over a long time, with the vertical Potential Gradient (PG) the most commonly observed quantity. In general, the PG responds to local influences from weather, aerosol effects on charge exchange, and variability in the global atmospheric electric circuit. Different methods have been used to classify PG data, for example through identifying days when conditions were considered relatively undisturbed, or by using meteorological information to identify days on which weather-related variability was negligible. Nevertheless, local effects can persist, especially in data obtained at continental sites. Hence, if long term changes in the global atmospheric electric circuit are to be investigated, the local effects need first to be reduced or, ideally, removed.Recent work has demonstrated a close relationship between the PG at some sites and ocean temperatures modulated by the El Niño Southern Oscillation, through the associated changes in the global atmospheric electric circuit ([1],[2], [3]). The expectation of such a relationship can be used to test methods of removing and reducing local effects in PG data. A method based on the Carnegie curve – the hourly variation known to be present in the global circuit – is discussed here. Through comparison of hourly PG data from a site with the Carnegie curve, outlier values lying beyond the usual range of global circuit changes can be identified and removed. The remaining data can then be used to construct new daily or monthly averages with reduced local variability, evaluated by comparison with global circuit changes associated with the El Niño Southern Oscillation. References[1] R.G. Harrison, K.A. Nicoll, M. Joshi, E. Hawkins: Empirical evidence for multidecadal scale Global Atmospheric Electric Circuit modulation by the El Niño-Southern Oscillation Environ Res Lett 17, 124048 (2022) https://iopscience.iop.org/article/10.1088/1748-9326/aca68c[2] N.N. Slyunyaev, N.V.I lin, , E.A. Mareev,.G. Price: A new link between El Nino - Southern Oscillation and atmospheric electricity, Environ. Res. Lett., 16, (2021) https://doi.org/10.1088/1748-9326/abe908 [3] R.G. Harrison, M. Joshi, K. Pascoe: Inferring convective responses to El Niño with atmospheric electricity measurements at Shetland Environ Res Lett 6 (2011) 044028  http://iopscience.iop.org/1748-9326/6/4/044028/ 
Optimizing low flow predictions in river systems: a multi-objective, multi-gauge calibration approach for process-based hydrological models
Authors: Künne Annika , Mimeau Louise , Lauvernet Claire , Devers Alexandre , Branger Flora , Kralisch Sven
Published: February 2023

Understanding the variations of streamflow is critical for studying the ecology of river systems. Low flow periods can pose significant pressures to river ecosystems, including flow intermittence, drying, increasing water temperature or pollutant concentration. Process-based spatially distributed hydrological models, can be used to simulate streamflow along river networks and provide valuable insights to study river ecology. However, until now, the use of these models to simulate streamflow at a high resolution, with a focus on low flow periods, has been limited. Therefore, traditional calibration techniques need to be adapted and refined to effectively address the challenges of sustainable river system management.In this study, we present a new approach to calibrate a process-based spatially distributed hydrological model (JAMS/J2000) to optimize the simulation of low flows in river systems. This approach combines traditional efficiency criteria (KGE, NSE, pBias, RMSE, etc.) with hydrological signatures specific to low flows (KGE(sqrt(Q)), 10th quantile, base flow index, etc.) to optimize the model at multiple gauging stations. In order to select the optimized parameter set, simulated ensembles of different parameter sets were generated using Latin Hypercube sampling and an objective function developed that combines the efficiency criteria at each gauging station. This allowed us to evaluate the performance of multiple potential parameter sets and select the one that optimizes the simulation of low flows in the river system.This calibration method was applied in 6 mesoscale catchments in different European countries (Croatia, Spain, Finland, France, Hungary, Czech Republic), which cover different ecoregions in Europe. The study was conducted as part of the Horizon 2020 DRYvER project (Datry et al. 2021). Our results show that the integration of hydrological signatures in the objective function has a strong impact on the calibration procedure and improves model performance during low flow periods.Datry et al. (2021) Securing Biodiversity, Functional Integrity, and Ecosystem Services in Drying River Networks (DRYvER). Research Ideas and Outcomes. https://doi.org/10.3897/rio.7.e7775
Application of Empirical Models for Assessment of the Atmospheric Ionization During a Geomagnetic Reversal
Authors: Svensmark Jacob
Published: February 2023

The most recent geomagnetic reversal of Earth’s magnetic dipole field, the Matuyama-Brunhes reversal event, took place 0.78 Ma ago. Detailed spatio-temporal paleomagnetic data have been made available for this time period. Geomagnetic reversals would be expected to impact the cosmic ray flux and in turn affect ionization rates of the atmosphere. In this study, empirical models are used to produce ionization rates for the entire globe during the Matuyama-Brunhes reversal.

The model takes the paleomagnetic timeseries data as input, and outputs 3D time series of the ionization rates of the atmosphere. It is shown, that ionization rates increase at low latitudes as the dipole field weakens. The increase is ~25% at the surface, and up to a factor of 5 in the upper atmosphere. The globally averaged ionization rate increase ranges from 13% at the surface and up to a factor of 2 in the upper atmosphere. Polar regions are largely unaffected. Lastly, we find that the reversal has a big influence on the much faster ionization rate changes caused by the solar 11-year cycle: The change in ionization between solar minimum and solar maximum increases up to two orders of magnitude depending on the strength of the geomagnetic dipole field, such that a weaker dipole field causes a stronger 11-year cycle and vice versa. 
Improved Terrain Modelling to aid flood mapping in coastal cities
Authors: Vallette Anne , Beck Anne-Laure , Jones Martin , Cook Harry , Taji Mohamed Amine
Published: February 2023

Coastal areas are recognized as the most at risk due to climate change. They exhibit low-lying elevation, very high urban density and valuable economical assets. Sea level rise, storm events and coastal floods that are increasingly frequent and more powerful will increase damage to fragile coasts. Human activities (especially the reduction in natural defences), sediment balance and natural phenomenon are disrupted and increase the coast’s vulnerability.As part of the GDA-DR initiative, we aim to produce some new indicators derived from EO to better understand the coastal system. As part of these new indicators, improved flooding maps are being developed using corrected elevation data and additional layers to better represent water behaviour in coastal cities. The Copernicus DEM GLO-30m is proving too crude to provide suitable flood modelling. It offers an accuracy of 4m, leading to an accuracy of earth features’ localization of less than 2.6 m. By using LIDAR measurements from the ISS-borne GEDI sensor and additional altimeter missions such as ATLAS on-board the ICESAT-2 satellite, we provide an improved and corrected DSM and DTM
Additional layers produced for DEMs correction are used to improve floods modeling such as land cover maps to extract drag coefficients and 3D settlement layers to take into account channelling effects.
This new approach can provide improved flood maps to better support flood mitigation planning. We propose to present DSM and DTM, for Dili in Timor Leste, based on the most recent space-lidar data, GEDI (2019-2021) and of IceSAT-2/ATLAS (2019- on going) and hoe those new DEMs can impact flood risk assessment.
Spatial association between talc-rich mineralization and sulfide-bearing deposits in a newly discovered inactive and weakly actie fields (Mid-Atlantic Ridge)
Authors: Pelleter Ewan , Cathalot Cecile , Dupré Stéphanie , Rospabe Mathieu , Giunta Thomas , Audrey Boissier , Cheron Sandrine , Rovere Mickael , Bonnet Robin , Ferrand Paco , Leroy Laetitia , Germain Yoan , Guyader Vivien , Donval Jean-Pierre , Fouquet Yves ,   Ewan Pelleter
Published: February 2023

Since 1977 and the discovery of the first high temperature (HT) hydrothermal vent, more than 300 sites are known (about 600 including inferred ones). Among these hydrothermal sites, the talc-rich deposit is the most recent class of hydrothermal system discovered on the seafloor [1]. Only three talc-rich deposits have been described so far: (i) the active Von Damm Vent Field (VDVF), (ii) the inactive St Paul’s and (iii) Conrad fracture zones deposits [2]. These hydrothermal sites are associated with lower crustal rocks and/or serpentinized peridotites and might be widespread at slow or ultraslow spreading ridge. However, no clear spatial or temporal relationship of this new class of hydrothermal system and the “black smoker”-like system has been highlighted. During the HERMINE (March-April 2017) and HERMINE2 (July-August 2022) cruises [3], [4], two hydrothermal areas with talc-rich deposits have been discovered during Nautile HOV dives. The first one (23°N) is an inactive hydrothermal area located 28km northwest of the Snake Pit vent field (25km west of the axial rift). At least two deposits have been observed: (i) a talc-silica deposit and (ii) a fully oxidized SMS-type deposit characterized by copper concentrations up to 3.3wt.%. The second hydrothermal area (26°N) is composed of one large and weakly-active deposit composed of silica-sulfides rocks and at least two small talc-silica deposits. To our knowledge, this is the first time that such a spatial relationship has been described between these two classes of deposits. The preliminary results on these newly discovered hydrothermal field will be presented here. [1] Hodgkinson et al. (2015) Nat.. Commun 6:10150doi: 10.1038/ncomms10150 .[2] D’Orazio et al. (2004) Eur. J. Mineral. 16, 73-83[3] Fouquet and Pelleter (2017), https://doi.org/10.17600/17000200[4] Pelleter and Cathalot (2022),https://doi.org/10.17600/1800185
Extreme wind gusts assessment in France
Authors: Bertrand Nathalie , Gaonac'h Adrien , Delattre Hugues , Sabre Maeva , Li Laurent
Published: February 2023

Extreme wind phenomena generated during convective events are reported every year in France and cause significant material losses. In 2022, several significant events were observed, for example in Normandy in June where a kite surfer lost his life or in August in Corsica where a new wind gust record was recorded (225km/h). However, convective wind gusts are not considered in the design process of residential and industrial infrastructures. Therefore, our study assesses the available databases on convective wind speeds monitored or estimated by MeteoFrance and Keraunos for the period 2000-2019 in order to define a methodology to estimate the wind gusts return level.Since all these convective events occur during a thunderstorm, the originality of this work was to use lightning data to separate convective from non-convective events. In addition, we considered all available data by projecting them onto the same grid (Meteorage lightning grid with 25 km resolution). A first probability analysis and conditional probabilities knowing the occurrence of a thunderstorm were deduced over the period and by seasons.Then, we will focus on a very convective region (North-East of France) to evaluate the possibility to estimate the return level of wind gusts with the designed available dataset.
Regime shifts in a euxinic marine lake
Authors: Dominović Iva , Marguš Marija , Dutour Sikirić Mathieu , Ciglenečki Irena
Published: February 2023

Numerous limnological studies have been investigating lake overturning regimes in the frame of possible future climate scenarios, mainly regarding the predicted surface air temperature change. Overturning regime shifts are expected to manifest in the stratification onset and offset timing, as well as in stratification duration. In addition, the lakes' vertical water column is expected to become more stable, and thus less inclined to overturn. Since aquatic life in the lake depends thoroughly on its phenology, the predicted regime shifts are going to influence the whole lake ecosystem, along with the microclimate of its surrounding area.An interesting example of regime shifting can be found in the central part of the Adriatic coast (43° 32' N, 15° 58' E). Lake Rogoznica (also known as "Dragon's Eye" lake) is a marine lake that is connected to the nearby Adriatic Sea through the porous karstic landscape. Although this connection is confirmed by high salinity values that reach those found in the surrounding sea (~38 PSU) and the visible tides, the newest research suggests that the complete overturning of the lake is governed by the delicate balance between the freshwater input (precipitation and runoff) and seawater input (Adriatic Sea), together with substantial surface air temperature fluctuations. Namely, Rogoznica Lake seems to exhibit complete overturns with irregular periodicity: sudden and abrupt holomixis occurred in the Autumn of 1997, 2011, 2016, 2020, and 2021. Another peculiarity of the lake is the complete anoxia with high levels of free sulfides that accompanies every such event, and the consequent mass mortality of the lake's aerobic life - the complete opposite of the oxygenation effect that seasonal overturning usually has in lakes.It is still unclear whether sudden anoxic holomixis and their frequency are a consequence of local tourist activities, regional climate variability, or climate change affecting the Mediterranean, as the effects of all mentioned could have an intertwined effect on the small, complex system of Rogoznica Lake. In this work, we present the latest findings regarding the Rogoznica Lake water column stratification with a two-sided approach: a comprehensive sea-atmosphere measurements analysis and numerical modelling attempts.
Regional assessment of agricultural soil ecosystem services and bundles definition through spatial analysis. A regional approach in Navarre (Spain).
Authors: Antón Rodrigo , Virto Iñigo , Coblinski João Augusto , Cousin Isabelle
Published: February 2023

Soils play a crucial role in the sustainable delivery of a wide range of ecosystem services (ES), linking soil functions of ecosystems to human well-being and socio-economic activities. When such linkages are well recognized, in a medium to long-term trajectories in the delivery of soil-based ecosystem services (SES) in relation to climate and land use or soil management are poorly known, particularly when it is not question of individual services but to bundles of services and their relationships. The identification and assessment of bundles of ES, and the definition of reference thresholds represents a key point in the assessment of soil multifunctionality and in the monitoring of soil health.The region of Navarre (10,391 km2) is characterized by a high climatic variability, with a rainfall gradient ranging from >2500 mm in the north to <350 mm in the southeast, as the most significant natural division in the territory. This translates into a variability in terms of agricultural use, which represents 39% of the total area with 90.7% cropland and 9.3% grassland, and where more than 30% is irrigated. This agricultural use was characterized in the context of the LIFE NADAPTA project, which aims to improve the adaptive management of agriculture soils to climate change in the region. In the framework of this project, twelve zones with homogeneous conditions for plant growth were defined by combining biogeographical and vegetation series information. In a second step a network of more than 150 agricultural plots within the region were defined, where a set of soil indicators were measured, including topsoil organic carbon, available water holding capacity and bulk density.Going a step further, this work proposes the assessment of the SES provided by the agricultural soils in the region according to different stratification options of the territory, with the aim of identifying patterns in the support of SES within these stratifications. The hypothesis of the work is that a correct stratification of the territory can allow the clustering of the territory in homogeneous service providing areas and, therefore, identify bundles of SES and define reference thresholds.To this end, a first phase involved the identification and selection of the main SES provided by the soils in the region and the definition of a set of indicators for their evaluation. The SES considered are i) biomass production, ii) erosion control, iii) climate regulation and iv) hydrological control. The definition of SES indicators has been done using the cascade as a general indicator framework. The set of indicators are going to be evaluated in a second phase of the work at the regional scale according to different stratification options within the region: no stratification, NADAPTA zoning, land use and climatic stratification.
Has the (West) Antarctic Ice Sheet already tipped?
Authors: Reese Ronja , Garbe Julius , Hill Emily A. , Urruty Benoît , Naughten Kaitlin A. , Gagliardini Olivier , Durand Gael , Gillet-Chaulet Fabien , Gudmundsson G. Hilmar , Chandler David , Langebroek Petra M. , Winkelmann Ricarda
Published: February 2023

Observations of ocean-driven grounding line retreat in the Amundsen Sea Embayment in Antarctica raise the question of an imminent collapse of the West Antarctic Ice Sheet. Here we analyse the committed evolution of Antarctic grounding lines under the present-day climate. To this aim, we run an ensemble of historical simulations with a state-of-the-art ice sheet model to create model instances of possible present-day ice sheet configurations. Then, we extend the simulations to investigate their evolution under constant present-day climate forcing and bathymetry. We test for reversibility of grounding line movement at different stages of the simulations to analyse when and where irreversible grounding line retreat, or tipping, is initiated.
CeaseFire: from scientific knowledge to operational tools for fire combat and management
Authors: Nunes Sílvia A. , DaCamara Carlos C. , Trigo Ricardo M. , Trigo Isabel F. , Gouveia Célia M. , Libonati Renata , Belém Liz B. C.
Published: February 2023

Forest fires are a global phenomenon with severe and destructive impacts at the ecological, environmental, socio-economic and health levels. Portugal, like all Mediterranean Europe, is recurrently affected by large wildfires, particularly intensive during the summers of 2003, 2005 and 2017. The latter is remembered because of the 500 000 hectares of burned area and the at least 116 deaths in the fire season.CeaseFire is a website that aims at converting the scientific knowledge produced at universities and research institutes into useful and user-friendly tools that provide information on fire activity and meteorological fire danger tailored to the needs of the fire community in Portugal and assist in decision making on fire management and combat and on fire damage mitigation. The website, relying on information from the LSA SAF project, provides maps and data of (1) components of the Fire Weather Index System;(2) Fire Radiative Power (FRP) released by wildfires (3) classes of meteorological fire danger, ignition potential and aftermath; (4) outlooks of the fire season severity; and (5) prescribed burned classes. The site has been sponsored by The Navigator Company, a leading force in the global pulp and paper market since the operational start of the website in 2016. The number of registered users has increased up to more than 1 600 within the fire community, comprising firemen, civil protection officers, municipalities, academic researchers and private owners. In recent years E-Redes, a national electricity distribution utility service, has also been supporting the development of the website.CeaseFire is sufficiently flexible to include other tools and be implemented in other regions. In this context, the feedback provided by users and companies has been decisive to improve the tools and products, and extend the site to other geographical areas, namely the Zambezia province in Mozambique and, more recently, the Brazilian Pantanal.Research work was funded by the Portuguese Fundação para a Ciência e a Tecnologia (FCT) I.P./MCTES through national funds (PIDDAC) IDL (UIDB/50019/2020), project FIRECAST (PCIF/GRF/0204/2017) and by EUMETSAT Satellite Application Facility on Land Surface Analysis (LSA SAF).
On the understanding of the North Atlantic storm conditions responsible for coastal flooding along the Western European coast
Authors: Lobeto Hector , Menendez Melisa
Published: February 2023

Water level at the coast integrates several components from different genesis. This study focuses on the climate-related component of extreme coastal water levels, i.e. the variations in water level over time due to the atmospheric and oceanic circulation variability and their interaction. The extreme climatic component of coastal water levels mostly integrates the storm surge, which represents the sea level variations due to atmospheric wind and pressure drivers, and the wave set-up, which represents the coastal water level variations induced by wind waves. Extreme events of the climatic component of coastal water levels under storm conditions are a major hazard in coastal impacts. These extreme events significantly increase coastal total water levels, which may result in coastal damage through catastrophic flooding episodes.This study assesses the atmospheric storm conditions in the North Atlantic Ocean linked to extreme climate-induced water levels along the Atlantic coast of Europe. A coastal water level indicator that integrates the storm surge and wind wave set-up components is computed first. North Atlantic atmospheric wind-pressure synoptic patterns are classified, identifying the storm-related patterns most probable to cause extreme water level events along the Western European coast. In addition, the track of the storms causing coastal water level extremes are identified and its main characteristics are analyzed (e.g., track orientation, storm intensity, landfall latitude). Results allow to unravel the differences between coastal regions regarding the characteristics of the storms potentially responsible for coastal impacts. For completeness, the projected changes in the storm conditions causing coastal climate-induced water level extremes by the end of the century due to climate change are explored.
Changes in land surface effects on organised convection in a convection-permitting climate projection
Authors: Klein Cornelia , Barton Emma , Taylor Christopher
Published: February 2023

Convection-permitting (CP) climate simulations represent a major advance in capturing land surface effects on convection. From observational analyses in West Africa, we know that land surface conditions are a major driver of storm initiation as well as intensification during later stages of the storm life cycle. Dry soils of 10 km to several 100s of km scale can cause anomalous warming of the planetary boundary layer and affect horizontal circulations, regional moisture convergence as well as instability. However, to date it remains unclear whether, in a warming climate, larger and more intense storms may change the scale and frequency of surface patterns, feeding back on these identified processes. Here, we evaluate the ability of a pioneering convection-permitting (4.4km) pan-African climate simulation to capture the observed land effects on the pre-convective environment in West Africa and subsequent storm characteristics. This is compared to a CP climate projection representing a decade under a very high emission scenario around 2100 in order to reveal potential changes in process interactions and consequences for organised convection in the future. 
A Novel Numerical Approximation Method for Computations with Spatially Correlated Observation Error Statistics in Data Assimilation
Authors: Hu Guannan , Dance Sarah L.
Published: February 2023

Convection-permitting data assimilation requires observations with high spatial density and high temporal frequency to provide information on appropriate scales for high resolution forecasting. Those observation types (e.g., geostationary satellite data) were found to exhibit strong spatial error correlations. Explicitly introducing correlated error statistics in the assimilation may increase the computational complexity and parallel communication costs of the matrix-vector multiplications with the observation precision matrices (the inverse observation error covariance matrices). Therefore, without suitable approaches we cannot take full advantage of the new observation uncertainty estimates. In this work, we present a new numerical approximation method, called the local SVD-FMM, which is developed based on a particular type of the fast multipole method (FMM) using a singular value decomposition (SVD), and a domain localization approach. The basic idea of the local SVD-FMM is to divide the observation domain into boxes of (approximately) equal size and then separates the calculations of the matrix-vector products according to the domain partition. These calculations can be done in parallel with very low communication overheads. Moreover, the local SVD-FMM is easy to implement and applicable to a wide variety of the precision matrices. We applied the local SVD-FMM in a simple variational data assimilation system and found that the computational cost of the variational minimisation was dramatically reduced while preserving the accuracy of the analysis. This new method has the potential to be used as an efficient technique for practical data assimilation applications where a large volume of observations with mutual error correlations needs to be assimilated in a short period of time.
Morphodynamic response on hydroclimatic conditions - A 50 year time-series of a northern river system
Authors: Blåfield Linnea , Sadeqi Amin , Alho Petteri , Kasvi Elina
Published: February 2023

In the rapidly warming sub-arctic areas, it is not known how the climate emergency driven changes in hydroclimatic conditions will affect the fluvio-morphological processes like bank erosion, sediment transport and meander migration, and especially their spatial-temporal mechanisms. At the moment, one big spring flood event is controlling the morphodynamics of the northern rivers, but the significance of this event is expected to decrease when the hydroclimatic conditions change and larger amount of the annual precipitation is expected as rainfall during autumn and winter months instead of snow. In this study, we utilize a 50 year hydroclimatic time-series together with 21 years of bank erosion and meander migration observations from two meander bends in Northern Finland. The aim of this study was to find the main controlling hydroclimatic factors for hydro-morphological processes, like meander migration and sediment transport, and analyse the changes and trends of these factors during the past 50 years. These observations were then used to forecast, how these processes will behave in the future under the changing hydroclimatic conditions in the rapidly warming high latitude areas. We used time-series of historical aerial imagery, geometric levelling data, sediment sampling and Terrestrial Laser Scanner to measure and analyse the bank erosion volume, sediment transport and bend migration in the past, present and future. A series of statistical analysis was then performed for the hydroclimatic time-series to recognise trends and to link the annual events with bend migration, erosion and transport volume. The results indicate how these unique northern river systems are responding to hydroclimatic changes and how the hydro-morphodynamics will be in the future. The results help adapting the river management, flood protection, mitigation strategies for extreme fluvial events in present and in the future at high latitudes.
Interpretable probabilistic forecast of extreme heat waves
Authors: Lovo Alessandro , Herbert Corentin , Bouchet Freddy
Published: February 2023

Understanding and predicting extreme events is one of the major challenges for the study of climate change impacts, risk assessment, adaptation, and the protection of living beings. Extreme heatwaves are, and likely will be in the future, among the deadliest weather events. They also increase strain on water resources, food security and energy supply. Developing the ability to forecast their probability of occurrence a few days, weeks, or even months in advance would have major consequences to reduce our vulnerability to these events. Beyond the practical benefits of forecasting heat waves, building statistical models for extreme events which are interpretable is also highly beneficial from a fundamental point of view. Indeed, they enable proper studies of the processes underlying extreme events such as heat waves, improve dataset or model validation, and contribute to attribution studies. Machine learning provides tools to reach both these goals.
We will first demonstrate that deep neural networks can predict the probability of occurrence of long-lasting 14-day heatwaves over France, up to 15 days ahead of time for fast dynamical drivers (500 hPa geopotential height field), and at much longer lead times for slow physical drivers (soil moisture). Those results are amazing in terms of forecasting skill. However, these machine learning models tend to be very complex and are often treated as black boxes. This limits our ability to use them for investigating the dynamics of extreme heat waves.
To gain physical understanding, we have then designed a network architecture which is intrinsically interpretable. The main idea of this architecture is that the network first computes an optimal index, which is an optimal projection of the physical fields in a low-dimensional space. In a second step, it uses a fully non-linear representation of the probability of occurrence of the event as a function of the optimal index. This optimal index can be visualized and compared with classical heuristic understanding of the physical process, for instance in terms of geopotential height and soil moisture. This fully interpretable network is slightly less efficient than the off-the-shelf deep neural network. We fully quantify the performance loss incurred when requiring interpretability and make the connection with the mathematical notion of committor functions.
This new machine learning tool opens the way for understanding optimal predictors of weather and climate extremes. This has potential for the study of slow drivers, and the effect of climate change on the drivers of extreme events.
An energy-bandwidth basis for the internal wave model IDEMIX
Authors: Patel Ankitkumar , Olbers Dirk , Pollmann Friederike , Eden Carsten
Published: February 2023

Small-scale turbulent mixing plays an important role for the large-scale ocean circulation, but is unresolved in numerical ocean models. Since breaking internal gravity waves (IGWs) are a major source of this mixing, energetically consistent mixing parameterizations consider the internal wave energy balance. One such parameterization can be achieved with the aid of the IDEMIX (Internal Wave Dissipation, Energy and Mixing) model, which describes the generation, propagation and dissipation of internal wave energy and successfully reproduces energy and mixing estimates derived from Argo float observations. We extend the IDEMIX energy model to describe a coupled system of predictive equations for energy and bandwidth, where bandwidth is a shape parameter of the IGW energy spectrum fixing the number of excited vertical modes. The correlation between energy and bandwidth is a power law with an exponent given by the dynamical parameters. The power law agrees with energy and spectral shape estimates from finestructure observations by Argo floats. We present the coupled energy-bandwidth IDEMIX model in a stand-alone setup and preliminary results of how it affects vertical mixing and the ocean state in a global ocean model.
Assessment of geothermal energy resources and in Armenia
Authors: Meliksetian Khachatur , Navasardyan Gevorg , Sargsyan Lilit , Medvedev Andrey , Grigoryan Edmond , LaFemina Peter , Connor Charles , Lavrushin Vassily , Sahakyan Elya , Savov Ivan , Toghramadjian Natasha
Published: February 2023

Armenia is a landlocked country in the South Caucasus region, situated between Iran, Georgia, Azerbaijan and Turkey, with population of about 3.0 million. Since Neogene to Quaternary times, the territory of Armenia has been located in a continent-continent collision zone (i.e., collision of the Arabian and Eurasian plates) and exposed to transpressional tectonics resulting in widespread and long-lasting polygenetic and monogenetic volcanic activity.The studies of spatial density of vents in Armenia (Weller et al., 2018, Sugden et al.  2021) demonstrate that Armenia is one of the densest clusters of Quaternary monogenetic volcanoes on Earth: in total, 516 volcanoes are mapped within the area of  ~30,000  km2. Most of the monogenetic volcano clusters are oriented NW to SE, perpendicular to the major stress direction related to the movement of the Arabian plate from SW to NE.Several active faults and potentially active and active volcanic systems exist in the country and many historical earthquakes have been recorded. The geology of Armenia with its volcanoes and active faults being potential source of hazards at the same time, has an important potential for geothermal energy, whilst much of Armenia’s current energy production is from imported fossil and nuclear fuel.It is noteworthy, that hundreds of sources of thermal mineral waters exist in Armenia and most of them are found in close proximity to volcanic systems and active faults. Our preliminary geochemical studies of mineral waters aiming to apply geochemical thermometers to investigate the formation temperature of waters demonstrate several geothermal anomalies in Armenia. This contribution will present unified geological, geophysical, volcanological, geochemical database with selection of promising sites for further studies of geothermal energy potential of Armenia, and some preliminary results of application of ambient noise tomography (ANT) and satellite data.