bluuebunny/crossref_metadata_2025 huggingface dataset:
Landslide hazard assessment for climate change adaptation of linear infrastructure: From the global scale to the Nordic scale
Authors: Palau Rosa M , Nadim Farrokh , Gisnås Kjersti , Vicari Hervé , Dijkstra Jelke , Gilbert Graham , Solheim Anders
Published: February 2023

Rainfall-induced landslides represent an important hazard in mountainous regions worldwide. Landslides commonly impact the functioning of infrastructure assets such as roads and railways and occasionally damage buildings or result in fatalities. In the Nordic region, rainfall-induced landslides constitute a significant hazard, accounting for a considerable amount of Norway's national landslide database entries.Because of climate change, the frequency of rainfall and soil moisture conditions that usually trigger landslides will become more variable. This leads to weaker predictions for the location and frequency of future landslide events from current models. Understanding how the landslide hazard will change can help plan mitigation along linear infrastructure and reduce the risk to the population.Here, we report the findings from the NordicLink project, financed by Nordforsk, where a methodology to characterise landslide hazard at a global scale has been adopted to develop Nordic hazard maps.The methodology to characterise the landslide hazard at a global scale has been developed within the activities of the "Global Infrastructure Resilience Index" (GIRI) project, funded by the Coalition for Disaster Resilient Infrastructure (CDRI). The method combines landslide susceptibility and rainfall to compute landslide probability at a global scale. The susceptibility map classifies terrains into five susceptibility classes by combining slope, vegetation, lithology, and soil moisture information from global datasets. Rainfall information has been obtained from the W5E5 dataset for the period 1979-2016 and the IPSL-CM6A-LR climate model from ISIMIP3b dataset SSP126 and SSP585 scenarios for the period 2061-2100. To characterise the rainfall triggering potential, the 24 h rainfall intensities have been used to distinguish between five rainfall hazard classes. Finally, a hazard matrix has been employed to combine landslide susceptibility and rainfall. The output is a probabilistic hazard map covering the world with a resolution of three arc seconds (approximately 90 m at the equator).In the NordicLink project, higher-quality Nordic-scale data and landslide inventories are used as input to the above-mentioned procedure to obtain probabilistic hazard maps covering Norway, Sweden, and Finland. The study concludes with a comparison between the NordicLink hazard maps and the (global) GIRI model. As expected, landslide hazard is higher in western Norway and decreases towards the East. Finland is the country with the lowest landslide hazard.
Modelling the future evolution of an alpine debris-covered glacier
Authors: Rückamp Martin , Morlighem Mathieu , Mayer Christoph
Published: February 2023

Debris-covered glaciers can react differently to external forcings than clean-surface glaciers. Depending on its thickness, a supraglacial debris layer impacts the glacier mass balance by either enhancing the surface melt or protecting the underlying ice. Based on previous works focusing on simple flowline geometries, we extended the model setup to three-dimensional complex geometries. The framework is implemented using the Ice-sheet and Sea-level System Model (ISSM) and applied to a typical alpine glacier geometry. Ice dynamics are solved on high-resolution with full-Stokes and coupled to the surface debris transport equation. The employed surface mass balance (SMB) model is capable of describing the melt rate for all debris thicknesses by including turbulent fluxes within the upper debris cover. This SMB formulation resolves the enhanced melt rates for a thin debris cover as well as the decreasing melt rates for thickening debris. To test the sensitivity of future projections of alpine glaciers on the debris layer, simulations are forced with high-resolution regional climate model (RCM) data from the EURO-CORDEX ensemble (RCP2.6 and RCP8.5).
Measurements of sediment flux in rivers with a multi-frequency echosounder
Authors: Höllrigl Jakob , Blanckaert Koen , Hurther David , Fromant Guillaume , Storck Florian R.
Published: February 2023

At present, SSC fluxes in rivers are typically estimated by multiplying the river discharge with theaverage suspended sediment concentration (SSC). The latter is typically obtained from optical turbiditymeasurements in one single point of the river cross‐section. The optical turbidity is converted inaverage SSC based on a relation that is derived from the laboratory analysis of regular SSC samples.This method has the disadvantages that it is based on a one‐point measurement and that it isexpensive.The SSC distribution in an entire profile – vertical or horizontal – can also be derived from thebackscatter of single‐frequency echosounders. The disadvantage of this method is that the particle sizeof the suspended sediment needs to be known in order to convert the profile of backscatter into aprofile of SSC.Here we present a hydro‐acoustic method based on multi‐frequency echosounding. Operating onmultiple acoustic frequencies allows estimating the mean particle size directly from the backscatter atthe different frequencies. The method based on multi‐frequency echosounding is illustrated withmeasurements on the Rhône River just upstream of Lake Geneva in Switzerland. The results arecompared to measurements based on optical turbidity measurements and to measurements based onsingle‐frequency echosounding.
Dam construction as an important anthropogenic modification triggers abrupt shifts in microbial community assembly in freshwater lake sediments
Authors: Zhou Xiaotian , Ruan Aidong
Published: February 2023

Microbial communities in freshwater lake sediments play a crucial role in regulating geochemical cycles and controlling greenhouse gas emissions. Many of them exhibit a highly ordered structure along depth profile. Besides redox effect, sediment stratification could also reflect historical transition. Dam construction dramatically increased in the mid-20th century and is considered one of the most far-reaching anthropogenic modifications of aquatic ecosystems. Here we attempted to identify the effect of historical dam construction on sediment microbial zonation in Lake Chaohu, one of the major freshwater lakes in China. The damming event in AD 1962 was coincidentally labeled by the 137Cs peak. Physiochemical and sequencing analyses (16S amplicon and shotgun metagenomics) jointly showed a sharp transition occurred at the damming-labeled horizon which overlapped with the nitrate-methane transition zone (NMTZ) and controlled the depth of methane sequestration. At the transition zone, we observed significant taxonomic differentiation. Random forest algorithm identified Bathyarchaeota, Spirochaetes, and Patescibacteria as the damming-sensitive phyla, and Dehalococcoidia, Bathyarchaeia, Marine Benthic Group A, Spirochaetia, and Holophagae as the damming-sensitive classes. Phylogenetic null model analysis also revealed a pronounced shift in microbial community assembly process, from a selection-oriented deterministic community assembly down to a more stochastic, dispersal-limited one. These findings delineate a picture in which dam-induced changes to the lake trophic level and sedimentation rate generate great changes in sediment microbial community structure, energy metabolism, and assembly process.
Monitoring an ephemeral stream with a Teensy 3.2 + audio shield to determine water level only from the noise of a stream
Authors: Fässler Linus , Ceperley Natalie , Leiser Peter , Schaefli Bettina
Published: February 2023

River networks in the Alps are very complex and hold many unanswered research questions. For example, various assumptions must be made to when studying tributaries and small rivers. Namely, there is not a widely accepted tool to measure streamflow in small, mountain streams that can overcome their specific challenges affordably without large installations. For example, alteration between extremely high and no discharge volume is characteristic of intermittent rivers and ephemeral streams (IRES). Conventional measuring devices all require streambed installation, which exposes them to displacement or destruction by abruptly rising water levels. One solution, thus, is to remove the sensor from the streambed and measure from a distance. We have experimented with an acoustic sound recorder mounted above the stream as an alternative tool to assess water level. We designed a low-cost audio sensor powered by a microcontroller with an audio shield specifically for recording IRES. To ensure reproducibility, we used Arduino for programming the Teensy 3.2. Images of the water level in an IRES were simultaneously captured when possible (daylight) and used for calibration. The water level visible in the images correlated well with that determined from the audio recordings from our self-developed audio sensor (R2 = 95%). Based exclusively on the audio recording of an IRES, we can obtain a time series of the water level, at least when water was present. We are currently unable to determine consistently whether water is present nor state with certainty when the streambed is dry based solely on acoustic data. Nevertheless, this new sensor allows us to measure an alpine channel network at more locations and over longer time periods than previously feasible.
Self-Supervised Contrastive Model for Flood Mapping and Monitoring on SAR Time-Series
Authors: Yadav Ritu , Nascetti Andrea , Azizpour Hossein , Ban Yifang
Published: February 2023

Flooding is a natural disaster that has been increasing in recent years due to climate and land-use changes. Earth observations, such as Synthetic Aperture Radar (SAR) data, are valuable for assessing and mitigating the negative impacts of flooding. Cloud cover is highly correlated with flooding events, making SAR a preferable choice over optical data for flood mapping and monitoring.Traditional methods for flood mapping and monitoring using SAR data, such as otsu and CVA, can be affected by noise, false detections due to shadows and occlusions, and geometric distortions. While automatic thresholding can be effective with these methods, manual adjustment of the threshold is often required to produce an accurate change map. Supervised deep learning methods using large amounts of labeled data could potentially improve the accuracy of flood mapping and monitoring. We have a large amount of earth observation data, but the availability of labeled data is limited and labeling data is time-consuming and requires domain expertise. On the other hand, Supervised model training on small datasets causes severe generalizability issues when inference is taken on a new site. To address these challenges, we propose a novel self-supervised method for mapping and monitoring floods on Sentinel-1 SAR time-series data. We propose a probabilistic model trained on unlabeled data using self-supervised techniques, such as reconstruction and contrastive learning. The model is trained to learn the spatiotemporal features of the area. It monitors the changes by comparing the latent feature distribution at each time stamp and generates change maps to reflect the changes in the area. We also propose a framework for flood monitoring that continuously monitor the area using time series data. This framework automatically detects the change point i.e. when the major change started reflecting on available SAR data. Our continuous monitoring framework combined with a better temporal resolution (better than Sentinel-1) can potentially detect flood events in an early stage, allowing for more time for evacuation planning. The model is evaluated on nine recent flood events from ‘Mekong’, ‘Somalia’, ‘Scotland’, ‘Australia’, ‘Bosnia’, ‘Germany’, ‘Spain’, ‘Bolivia’, and ‘Slovakia’ sites. We compared our results with traditional methods, and existing supervised and unsupervised methods. Our detailed evaluation indicates that our model is more accurate and generalizable to new sites. The model achieves an average Intersection Over Union (IoU) value of 70% and an F1 score of 81.14%, which are both higher than the scores of the previous best-performing method. Overall, our proposed model’s improvement range from 7-26% in terms of F1 and 8-31% in terms of IoU score. 
Mediterranean catchments post-fire hydrogeological behavior and water quality: insights from the Pisano Mount area (Tuscany, Italy)
Authors: Nigro Matteo , Giannecchini Roberto , Doveri Marco , Menichini Matia , Baneschi Ilaria
Published: February 2023

Wildfires are recognized as one of the most affecting ecological agents, altering geomorphological processes, hydrologic cycles, and water quality. On average from 50,000 to 65,000 fires occur in Europe every year, burning approximately 500,000 ha of forested areas. Between September 2018 and February 2019 two large wildfires burnt nearly 1,400 ha of forests and farmlands in the Pisano Mount area (northwestern Tuscany). The mountainous morphology of the area linked to the proximity to the sea causes high precipitation variability and intensity. This, joined with low permeability bedrock (mainly quartzites, schists, and phyllites) and with the extensive vegetation coverage, make the study site a hot spot for surface waters analysis. Moreover, burnt catchments are of primary importance in the recharge processes of the groundwater resources of the costal plain, which are exploited by a large number of inhabitants and agricultural facility. Consequently, the present study is aimed at understanding and quantifying the wildfire impacts on the hydrogeological dynamics and water quality in the studied catchments. Such impacts are being evaluated by comparing burnt and unburnt catchments, which were selected to be as similar as possible from geological, morphological, and vegetational perspectives. The multi-parameter selection method involved Principal Component Analysis and Distance analysis on many potentially feasible catchments. A network of automatic monitoring instruments was deployed on site. Five hydraulic sections of the main streams draining the area were monitored for hydraulic level and physico-chemical parameters. Hydrographs analysis was performed to infer differences in hydrogeological dynamics between burnt and unburnt basins. Monthly samples were collected for stream water and groundwater chemical analysis. In addition, four plate lysimeters were installed to sample soil water for its chemical characterization. The chemical analysis involved major anions and cations, trace elements, water isotopes, and organic compounds, to search for chemical perturbation potentially arising from the wildfire. The investigation highlighted various differences between the burnt and unburnt basin, mainly for the surface waters. The streams draining the burnt areas present different hydraulic behaviour and changes in physiochemical parameters in response to rainfall events. Moreover, the yearly variation of physiochemical parameters and chemical characteristics present an higher variance for those streams draining wildfire affected catchments.
Impacts of aerosol-cloud-radiation interactions on photovoltaic generation: case of Saharan dust outbreaks in March 202
Authors: Hoshyaripour Gholam Ali , Hermes Kilian , Seifert Axel , Bachmann Vanessa , Filipitsch Florian , Foerstner Jochen , Grams Christian , Hoose Corinna , Quinting Julian , Rohde Anika , Vogel Heike , Vogel Bernhard
Published: February 2023

Aerosols interact with radiation and clouds and thereby disturb radiative budget and temperature structure in the atmosphere. To account for these effects, numerical weather prediction models rely on climatological mean concentrations. This simplification may lead to large errors in the forecasted cloud cover and radiative fluxes especially during major aerosol events. For example, Saharan dust events often coincide with significant errors in shortwave radiation and thus, day-ahead photovoltaic forecasts in Europe. In this study we investigate errors in the short-range forecasts during Saharan dust outbreaks in March 2021, analyze possible causes and explore the solutions. We use the data from pre-operational forecasts performed with the ICOsahedral Nonhydrostatic model with Aerosols and Reactive Trace gases (ICON-ART) based on two experiments: without dust effects and with direct dust effect only. We compare model data with the measurements from satellite and in-situ instruments. The results reveal that the inclusion of direct radiative effects from prognostic dust improves the forecast in surface radiation during clear-sky conditions. However, dusty Cirrus clouds are strongly underestimated, pointing to the importance of representing indirect effects. To fill this gap, we develop and test corresponding sub-grid parameterization for dusty Cirrus in the ICON-ART model. Only with help of this parameterization ICON-ART is able to simulate the formation of the dusty cirrus, which leads to substantial improvements in cloud cover and radiative fluxes compared to simulations without this parameterization. This study confirms that a reliable photovoltaic forecast requires explicit treatment of aerosol-cloud-radiation in numerical weather forecast systems.
Long-term climatic trends for the Mediterranean region and their association with atmospheric circulation
Authors: Tzanis Chris G. , Nasl Pak Aris , Philippopoulos Kostas
Published: February 2023

The Mediterranean region is characterized by high vulnerability and changes in the atmospheric circulation and water cycle with significant socio-economic implications. Many regions in the Mediterranean basin face extreme climate events, while others do not exhibit the same sensitivity to climate change. In this study, the spatial and temporal variability of climatic parameters such as precipitation, temperature, and dew point are investigated. Furthermore, their sensitivity to changes in atmospheric circulation is also examined in terms of the response of the surface climatic conditions for different atmospheric circulation types. Long-term data are extracted from the ERA 5 reanalysis dataset over the period of 1961-2020 (70 years) at a spatial resolution of 0.25° × 0.25°. The analysis procedure includes the identification of trends in the time series using the non-parametric Mann-Kendall and Sen's methods. Regions with statistically significant trends are identified and discussed. Discrepancies are also examined between the trends identified from the ERA 5 reanalysis datasets and from E-OBS and in-situ climate records. The atmospheric circulation framework is based on the following a) Definition of the spatial and temporal scales, b) Standardization of the spatial and temporal time series and data reduction using Principal Components Analysis c) Classification and assignment of cases into atmospheric circulation regimes using the k-means algorithm and d) Atmospheric circulation regimes assembly of the daily regimes (weather types) catalog. Trends and high-impact areas of global warming are identified and therefore the association between atmospheric circulation and climate change is highlighted.
Drought increases the relative contribution of mycorrhiza-mediated mineral N uptake of Sorghum bicolor
Authors: Munene Rosepiah , Mustafa Osman , Loftus Sara , Ahmed Mutez , Dippold Michaela
Published: February 2023

Climate change scenarios forecast increasing droughts in large areas globally with significant effects on food production. Nutrient availability is an imperative factor for plant growth and it is greatly modulated by water availability. Nitrogen (N) availability extensively constrains plant growth in most terrestrial ecosystems especially in sub-Saharan Africa, where soils are unfertile and often degraded. How rhizosphere traits at the plant soil-interface affect N uptake in response to drought in N poor tropical soils remains elusive. We used 15N, and 13C pulse labelling to trace and quantify N transport from a root-restricted compartment by AMF across an air gap to the host plants coupled with quantifying the allocation of carbon to below-ground pools. Three sorghum genotypes were grown under optimal and water deficit conditions. By tracer analysis in the plant tissues, we assessed that drought enlarged uptake and delivery 15N by arbuscular mycorrhizal fungi (AMF) from the root restricted compartment across the air gap to the host plant. In addition, drought induced enhanced below-ground incorporation of recently assimilated carbon (C) into the microbial biomass pool both in rhizo-hyphosphere and hyphosphere. Enzyme assays revealed that whereas potential enzymatic reaction (Vmax) of chitinase was reduced under drought, that of leucine amino peptidase (LAP) was upregulated by water scarcity suggesting that N input from protein mineralization was relatively enhanced to that of chitin following moisture limitation. Michaelis-Menten constant (Km) of LAP strongly increased by drought compared to that of chitinase which displayed genotype-specific shifts in rhizosphere enzyme systems. We conclude that in addition to AMF symbiosis, enzyme regulation and enhanced belowground C allocation are key strategies to enhance nitrogen uptake under adverse conditions of resource limitations.
Transpiration of Acacia plantations in a managed tropical peatland Sumatra, Indonesia
Authors: Suardiwerianto Yogi , Kurnianto Sofyan , Hidayat Muhammad Fikky , Simamora Nurcahaya , Harahap Mhd. Iman Faisal , Fitriyah Nurul Azkiyatul , Jabbar Abdul , Ghimire Chandra Prasad , Deshmukh Chandra Shekhar
Published: February 2023

Waterlogged and anoxic conditions facilitate the preservation of carbon-rich peat layers in tropical peatlands coexisting with peat swamp forests. Peatlands in Southeast Asia, which host one-third of the tropical peatland area, have high temperatures throughout the year and high soil moisture availability, which support high evapotranspiration rates. The majority of existing land cover in Southeast Asia peatland is a canopy-covered ecosystem. Therefore, these ecosystems are considered to support high transpiration rates. However, the understanding of transpiration rates and their governing factors for existing land cover in Southeast Asia peatlands remains poorly understood due to limited measurements.Here, we quantified transpiration rates and explored governing factors in Acacia crassicarpa plantations (fast-growing species, harvested on a 4-5 year rotation) in the coastal peatland of Eastern Sumatra, Indonesia, between 2020 and 2022. Transpiration was quantified by measuring in situ sap flow rate using the HFD8-50 and SFM1 (ICT International, Australia) during the plantation age of 2 to 4 years. We measured the sapwood cross-sectional area using an increment borer (Haglöf, Sweden). In addition, we implemented a sampling strategy that considered tree size, azimuth, height, and radial factors, to account for the variability and upscaling from tree to stand level of transpiration.Our results showed that the greatest source of variability to determine transpiration were the radial and tree size. On a diel and daily basis, tree transpiration was affected by vapour pressure deficit and solar radiation. Further, we did not observe a relationship between seasonal rainfall variations and transpiration. We found that stand-level transpiration in deeper groundwater level sites (around -80 cm below peat surface) was higher by 20% than those in shallower sites (around -40 cm below peat surface) due to the higher stand density and total sapwood area. Overall measured transpiration rates (0.8 – 1.0 mm d-1) represent 20-24 % of evapotranspiration measured by eddy covariance. This study provides the first insights into the eco-hydrological characteristics of the Acacia crassicarpa plantation and improves the understanding of water balance from this globally important ecosystem.
Terrestrial and aquatic leaf wax hydrogen isotope proxy system models: Recent advances and remaining gaps
Authors: Thomas Elizabeth , Cluett Allison , Cowling Owen , Gorbey Devon , Hollister Kayla , Kjellman Sofia , Lindberg Kurt
Published: February 2023

Constraining the hydrological response to past climate change can improve climate model predictions. These constraints are most useful when provided in variables that are native to climate models (e.g., precipitation or soil water isotope values during a defined season). Leaf wax hydrogen isotopes extracted from lake sediments are valuable proxies to reconstruct the hydrological cycle. In some lakes, multiple leaf wax compounds may provide information about different aspects of the climate system (e.g., precipitation isotope seasonality, growing season evaporation, etc.), increasing the amount of information we obtain from a single measurement. Yet, the pathway by which climate signals are recorded in leaf wax hydrogen isotopes can be complex, as the isotope signal is filtered through the environment (lake or soil water) and the sensor (integrating waxes from aquatic plants and from terrestrial plants throughout the lake’s catchment). This presentation will summarize our recent and ongoing research examining how climate signals are filtered through both the environment and sensor, with the goal of providing reconstructions in terms native to isotope-enabled climate models. We will highlight studies examining lake water isotope systematics and leaf wax sources to lake sediments, emphasizing aspects of these frameworks that are applicable to other stable water isotope proxies. We will also discuss outstanding questions and avenues for future research.
Long-time permafrost evolution in alpine bedrock: quantifying climate change effects with geoelectrical monitoring
Authors: Scandroglio Riccardo , Offer Maike , Krautblatter Michael
Published: February 2023

While climate change driven increase in air temperature has been correctly modeled in recent decades, the extent of its consequences is still uncertain. In high alpine environments, especially in steep rock walls, permafrost degradation reduces slope stability with critical consequences for people and infrastructures: to properly assess the risk, the rate of these changes must be monitored. In the last decades, electrical resistivity tomography (ERT) has been used in more than hundred studies to detect permafrost, but there are only limited long-term monitoring cases that mostly do not provide quantitative information. Here we compare ERT measurements from two alpine landforms with different altitude and lithology: Steintälli ridge (3160m asl, CH) and Mt. Zugspitze rock wall (2750 m asl, DE/AT). Standard procedures and permanently installed electrodes allow the collection of a unique dataset of consistent measurements since 2006. Supporting information like resistivity-temperature calibration from former studies, rock surface and borehole temperatures as well as active seismic refraction measurements enable an advanced quantitative interpretation of the results. Permafrost at both sites is close to disappearing and in both cases resistivity changes are evident and in good agreement with air temperature increase, although with different magnitudes according to the landform. The yearly 3D measurements of the Steintälli ridge show a sudden and conspicuous degradation (~40% of the volume in 15 years), while the monthly 2D monitoring of the north face of Mt. Zugspitze shows slow constant decrease in summer (~15% of the surface in 15 years) and a strong variation in winter in correlation with snow-height. For the first time we provide a quantification of alpine permafrost degradation rates in different landforms over 15 years. These datasets help to better understand the different characteristics of the thermal responses to the climate change induced stress on alpine permafrost environments.
Characterization of rockfall mechanisms and run-out in active volcano-tectonic areas: a case study from Ischia Island, Southern Italy
Authors: Massaro Luigi , Rauseo Federica , De Falco Melania , Marino Ermanno , Forte Giovanni , Santo Antonio
Published: February 2023

Ischia (Southern Italy) is a volcanic island of the Phlegrean Volcanic District that was recently affected by multiple geological hazards, including floodings, landslides, rockfall and earthquakes.In this study, rockfall stability is analysed, assuming as a case study a 400m-wide cliff made of Green Tuff and located on the western area of Mt. Epomeo. The two outcrops studied are located at 280 and 420 m a.s.l., above the site of Frassitelli, Forio d’Ischia, which is an area of high residential, touristic and agricultural importance. The former is a high-angle outcrop affected by tens of meters-long faults, whereas the latter is characterised by high-dip pinnacles.We analysed the fracture systems affecting the examined formation to compute the kinematic analysis of the potential rupture mechanisms and to perform numerical simulations of potential rockfall scenarios. The data acquisition was carried out by means of classical geological field surveys and structural analysis on Virtual Outcrop Models (VOM) obtained from images acquired by drones. The VOMs were analysed with ‘CloudCompare v2.10.2’ and ‘OpenPlot’ software. The former allowed the automatic digitalisation of the exposed discontinuities by applying the ‘Facets’ plugin, based on a least-square fitting algorithm (Fernández, 2005). ‘OpenPlot’ enabled the extraction of the geostructural information from the VOM, by computing the best-fit planes of the polylines manually drawn along the interference between the geological surface and the outcrop topography (Tavani et al., 2011).The measured and the extracted features were classified following their attitude. Three main sets were defined, striking N-S, NW-SE and NE-SW. The fracture dataset was used to perform a kinematic analysis with ‘DIPS’ software on the surface discontinuities extracted from ‘Facets’ plugin. The 'wedge sliding' resulted the most critical potential rupture mechanism to occur on the analysed outcrops. Successively, numerical simulations of rockfall scenarios were computed based on the acquired structural information. The latter permitted us to identify the maximum run out of the potential blocks and draw some consideration on the rockfall hazard of the area.
Deciphering the declining runoff in the Thaya river basin
Authors: Pavlik Petr , Fischer Milan , Vizina Adam , Parajka Juraj , Anderson Martha , Štěpánek Petr , Hanel Martin , Janál Petr , Feng Song , Zeman Evžen , Trnka Miroslav
Published: February 2023

This study aims at understanding the changes in the water balance in the Thaya river basin over the past 40 years. The Thaya River is one of the tributaries to the Danube basin with a catchment area of more than 13 000 km2. A number of hydroclimatic variables related to runoff were examined by a trend analysis based on Theil-Sen regression and Mann-Kendall tests for the two periods 1981–2020 and 2001–2020. The latter period was selected because it allows analysis of several relevant variables derived from the Moderate Resolution Imaging Spectroradiometer (MODIS). These variables ecompass snow cover, leaf area index and land surface temperature based actual evapotranspiration.
With our analyses we confirm previously found increasing trends in air temperature, ETo, and no trends in precipitation. We also found a consistent increase of ET during spring months and indication of summer decrease (not statistically significant). This change was associated with a significant increase of spring vegetation development followed by summer stagnation. We identified a significant trend decline in runoff, mainly in the upland sourcing areas. The correlation analysis reveals a different behavior along the elevation gradient, with evapotranspiration in the uplands being limited by energy and in the lowlands by water, especially in spring. During summer, however, the entire basin is often water-limited, with a more pronounced limitation in the lowlands. According to attribution analysis for the past 20 years, the significantly decreasing runoff is driven primarily by non-significantly decreasing precipitation, significantly increasing air temperature and vapor pressure deficit. Global radiation and wind speed affect the runoff only to a very limited extent. We conclude that complex adaptation measures reflecting the site specificity and elevation gradient are needed to sustain the water dependent sectors operating in the region facing increasing aridity. 
LSTMs for Hydrological Modelling in Swiss Catchments
Authors: Lott Christina , Martins Leonardo , Weiss Jonas , Brunschwiler Thomas , Molnar Peter
Published: February 2023

Simulation of the catchment rainfall-runoff transformation with physically based watershed models is a traditional way to predict streamflow and other hydrological variables at catchment scales. However, the calibration of such models requires large data inputs and computational power and contains many parameters which are often impossible to constrain or validate. An alternative approach is to use data-driven machine learning for streamflow prediction.In the past few years, LSTM (long short-term memory) models and its variants have been explored in rainfall-runoff modelling. Typical applications use daily climate variables as inputs and model the rainfall-runoff transformation processes with different timescales of memory. This is especially useful as delays in runoff production by snow accumulation and melt, soil water storage, evapotranspiration, etc., can be included. In contrast to feed-forward ANNs (artificial neural networks), LSTMs are capable of maintaining the sequential temporal order of inputs, and compared to RNNs (recurrent neural networks), of learning the long-term dependencies. [1]However, current work on LSTMs mostly focuses on the USA, the UK and Brazil, where CAMELS datasets are available [1, 2, 3]. Catchments at higher altitudes with snow-driven dynamics and sometimes glaciers are present in small number in these datasets (if at all). Systematic applications of LSTMs for streamflow prediction in climates where a significant part of the catchments are snow and ice dominated are missing. In this work, an FS-LSTM (fast slow-LSTM) previously applied in Brazil is adapted for Swiss catchments to fill this gap [3]. The FS-LSTM explored builds on the work of Hoedt et al. (2021) that imposed mass constraints on an LSTM, called MC-LSTM [4]. FS-LSTM adds a fast and slow part for streamflow, containing rainfall and soil moisture respectively. We will discuss benchmark results against an existing semi-distributed conceptual model widely used in Switzerland for streamflow simulation [5]. References:[1]: Kratzert et al., Rainfall-runoff modelling using Long Short-Term Memory (LSTM) networks, 2018.[2]: Lees et al., Hydrological concept formation inside long short-term memory (LSTM) networks, 2022.[3]: Quinones et al., Fast-Slow Streamflow Model Using Mass-Conserving LSTM, 2021.[4]: Hoedt et al., MC-LSTM: Mass-Conserving LSTM, 2021.[5]: Viviroli et al., An introduction to the hydrological modelling system PREVAH and its pre- and post-processing-tools, 2009.
A case study to investigate the role of aerosols reduction on the East Asian summer monsoon seasonal prediction
Authors: Cherchi Annalisa , Tourigny Etienne , Acosta Navarro Juan C , Ortega Pablo , Davini Paolo , Alessandri Andrea , Catalano Franco , van Noije Twan
Published: February 2023

In the late 20th century, both the East Asian and the South Asian summer monsoons weakened because of increased emissions of anthropogenic aerosols over Asia, counteracting the warming effect of increased greenhouse gases (GHGs). During the spring 2020, when restrictions to contain the spread of the coronavirus were implemented worldwide, reduced emissions of gases and aerosols were detected and found to be quite extended over Asia.Following on from the above and using the EC-Earth3 coupled model, a case-study forecast for summer 2020 (May 1st start date) has been designed and produced with and without the reduced atmospheric forcing due to covid-19 related restrictions in the SSP2-4.5 baseline scenario, as estimated and adopted within CMIP6 DAMIP covidMIP experiments (hereinafter “covid-19 forcing”). The forecast ensembles (sensitivity and control experiments, meaning with and without covid-19 forcing) consist of 60 members each to better account for the internal variability (noise) and to maximize the capability to identify the effects of the reduced emissions.The analysis focuses on the effects of the covid-19 forcing on the forecasted evolution of the monsoon, with a specific focus on the performance in predicting the summer precipitation over India and over other parts of South and East Asia. The results indicate that in 2020 a more realistic representation of the atmospheric forcing in the spring preceding the core monsoon season improves the skill of the predicted summer precipitation, mostly over East Asia. Beyond the testbed considered in this analysis, the result helps improving the understanding of the processes at work over the Asian monsoons regions, with positive implications on the usefulness of seasonal predictions products.
A worldwide coastal analysis of the wave systems
Authors: Mazzaretto Ottavio Mattia , Menéndez Melisa
Published: February 2023

Wave climate is usually characterized with the bulk parameters (Significant Wave Height, Peak Period, Mean Wave Direction). Local wind generated waves are however the result of the wave energy through a frequency-direction wave spectrum. One of the most common problems encountered using the bulk parameters is the loss of information concerning different wave systems. The ocean surface is a combination of waves coupled to the local wind (wind sea) or generated elsewhere (swells). The aim of this study is to analyze the coastal climate conditions of the wave systems. Wave directional 3-hourly spectral data from the 30yrs 1989-2020 historical time period at about 10.000 locations worldwide are used.

The methodology to obtain spectral partitions from the directional wave spectrum was initially proposed by Hanson and Jensen (2004) and based on the watershed algorithm (Vincent and Soille, 1991). Once the partitions are obtained, wind and swell/s are obtained.. Wind seas are identified using a wave age criterion, such that wind sea peaks lie within parabolic boundaries. Any partition whose peak falls within the wind sea region is considered to be forced by the wind and initially defined as wind sea. All wind seas partitions from a given input spectrum are combined. The swell wave systems are obtained from the aggregation of all the swell partitions, during the whole time, coming from the same direction, obtaining then a mean wave climate probability spectrum. This spectrum is further partitioned using the watershed algorithm.

Once the swell wave systems are obtained, the corresponding energy (m0) allows to estimate the dominance of the swells and the wind sea. In some areas the wind sea has higher energy than the swells (e.g. Gulf of Carpentaria, Baltic Sea), while other areas are dominated by a strong swell (e.g. south Atlantic European coast), or the coexistence of multiple swells (e.g. Pacific Islands). In general, for enclosed seas, wind sea and swell are concurrent. Overall, on the East coast of the continents the swells coexist with wind sea, whereas on the West coast the swells prevail.
Atom interferometry in the transportable Quantum Gravimeter QG-
Authors: Nuñez von Voigt Pablo , Heine Nina , Herr Waldemar , Schubert Christian , Timmen Ludger , Müller Jürgen , Rasel Ernst M.
Published: February 2023

The transportable Quantum Gravimeter QG-1 is based on the principle of atom interferometry with collimated Bose-Einstein condensates (BEC) to determine the absolute value of the local gravitational acceleration g, aiming for an unprecedented level of accuracy < 3 nm s−2. The QG-1 uses an atom-chip to produce well-defined magnetic fields, allowing high controllability of the atomic cloud and creating a BEC. After release from the magnetic trap into free fall, using well-controlled laser pulses the BEC is split, each part accumulating phase on its trajectory during free fall, and thereafter recombined, leading to self-interference. From the phase difference of the two parts of the BEC, the local gravitational acceleration g can be determined. Environmental vibrations contribute to the accumulating phase during free fall, leading to a disturbing phase shift of the interfering BEC. By measuring the high-frequency environmental noise with a classical accelerometer, this additional phase shift can be infered and corrected for in the determination of g.In this contribution tide-resolving results of the latest measurement campaign with implemented classical sensors to correct for high-frequency vibrations with an accelerometer and drifts with a tiltmeter will be presented, rendering an important milestone for the development of our QG-1.We acknowledge financial funding by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - Project-ID 434617780 - SFB 1464 TerraQ and under Germany’s Excellence Strategy - EXC 2123 QuantumFrontiers, Project-ID 390837967.
Methane emissions from the Baltic Sea nine days after the Nord Stream explosions
Authors: Reum Friedemann , Marshall Julia , Bretschneider Lutz , Glockzin Michael , Huntrieser Heidi , Gottschaldt Klaus-Dirk , Lampert Astrid , Lichtenstern Michael , Miller Scot M. , Pätzold Falk , Pühl Magdalena , Rehder Gregor , Roiger Anke
Published: February 2023

The sabotage of the Nord Stream pipelines on 26 September 2022 led to the largest event of methane venting to the atmosphere on record. The pipelines contained about 300 000 tonnes of methane, and an estimate based on Europe's ICOS network quantified the emissions to the atmosphere at 90 000-300 000 tonnes of methane in the first days of the event (Ramonet et al., 2022). The vast majority of methane that vented from the pipelines into the water likely escaped to the atmosphere near-instantly via bubble transport, which had largely ceased by 1 October 2022. However, a fraction dissolved into the water. To investigate the possibility of a "long tail" of release of this dissolved methane to the atmosphere, we conducted airborne surveys of the leak area on 5 October 2022. Methane data were recorded with a Picarro G2401m onboard the HELiPOD platform, a drag probe attached to a helicopter with a rope, down to 30 m above sea level. We observed methane enhancements of up to 300 ppb above atmospheric background, in an area about 30 km both up- and downwind of the leak locations. Using an inverse model of atmospheric transport, we show that the atmospheric data can be explained by an area source and estimate a source strength on the order of tens of tonnes of methane per hour on the day of observations. To better understand the spatial distribution of the emissions, especially emissions upwind of the leak locations, we further run a model of oceanic transport for tracers released at the leak locations and couple it to a Wanninkhof-model of diffusive emissions. The areal emission distribution we find with this model has some similarities to the emission pattern retrieved using the airborne measurements. We conclude that a significant amount of methane was dissolved in the Baltic Sea during the outgassing event following the Nord Stream explosions. Methane that was initially dissolved in the surface layer still escaped to the atmosphere days after the initial outgassing event.
Self-adaptive Laurentide Ice Sheet evolution towards the Last Glacial Maximum
Authors: Niu Lu , Knorr Gregor , Krebs-Kanzow Uta , Gierz Paul , Lohmann Gerrit
Published: February 2023

Northern Hemisphere summer insolation is regarded as a main control factor of glacial-interglacial cycles. However, internal feedbacks between ice sheets and other climate components are non-negligible. Here we apply a state-of-the-art Earth system model (AWI-ESM) asynchronously coupled to the ice sheet model PISM, focusing on the period when ice sheet grows from an intermediate state (Marine isotope stage 3, around 38 k) to a maximum ice sheet state (the Last Glacial Maximum). Our results show that initial North American ice sheet differences at 38 k are erased by feedbacks between atmospheric circulation and ice sheet geometry that modulate the ice sheet development during this period. Counter-intuitively, moisture transported from the North Atlantic warm pool during summer is the main controlling factor for the ice sheet advance. A self-adaptative mechanism is proposed in the development of a fully-grown NA ice sheet which indicates how the Earth system stabilizes itself via interactions between different Earth System components.
Field monitoring of cyclic freezing process: effect of air temperature on frozen layer thickness
Authors: Bočková Kateřina , Moya José , Macías Andrés , Vaunat Jean
Published: February 2023

Freezing is an important factor in soil degradation. In order to predict soil erosion in mountainous areas, the freezing process and the frequency and extent of freezing must be understood. This study aims to identify a relationship between air temperature and a depth of freezing, taking into account soil water content. The soil is considered to be frozen when all the free water within the pores freezes which, according to our numerical model, mainly occurs at temperatures slightly below 0°C. On the other hand, the temperature is not homogeneous in the soil as it is driven by the process of heat diffusion from the soil-atmosphere interface to depth, controlled by soil thermal conductivity and heat capacity, which depend on ice and water contents. As a consequence, the relationship between air temperature and the thickness of the frozen layer is not direct, and the relevance of using air temperature as a measure of frozen depth is to be evaluated.A small N-S-oriented claystone ridge in an Eastern Pyrenees badland is being monitored. A series of thermometers, water content sensors, and specific heat sensors are collecting data in 5-minute intervals on both sides of the ridge. The data show an attenuation of temperature oscillation with an increasing depth and a time delay of the surface temperature propagation. The differences in the soil temperatures on the north and south side are moreover showing the importance of solar radiation in the process. These observations are further integrated into a procedure allowing for the analysis of possible ad-hoc relationships between current and past air temperature and depth of the frozen layer.
Estimating the risk of large investments using Hurst-Kolmogorov dynamics in interest rates
Authors: Markantonis David , Dimitriadis Panayotis , Sargentis G.-Fivos , Iliopoulou Theano , Mamassis Nikos , Koutsoyiannis Demetris
Published: February 2023

Economies of scale, which minimize the cost of the unit, are vital for the prosperity of the society and the progress of civilizations. In order to achieve economies of scale, large investments have to be made. However, investments contain always a risk.  An important evaluation of the investment’s risk could be done by interest rates. In this study, we update our recently presented methodology from utilizing Markov assumptions and instead for the timeseries generation algorithm, we employ a stochastic model following the Hurst-Kolmogorov dynamics . The updated methodology is applied for interest rates in various historical periods and compared with the Markov-based one.