bluuebunny/crossref_metadata_2025 huggingface dataset:
Flood changes in Europe: from detection to attribution
Authors: Bertola Miriam , Viglione Alberto , Lun David , Blöschl Günter
Published: February 2023

Floods are the most frequent natural disaster in Europe, and there is evidence of changes in their magnitude and frequency during the last decades. Previous studies typically analysed trends in mean annual flood discharges. However, changes in larger and less frequent floods (e.g., the 100-year flood) as well as their causes have not yet been assessed in a quantitative and consistent way. This contribution describes the journey from the detection to the attribution of flood changes in Europe though a collection of data-based studies. A unique pan-European database of annual maximum discharges is used for the analyses. This presentation will answer the following three questions: (i) are changes in small and big floods different? (ii) what are the main drivers of those changes? and (iii) do small and large floods have the same drivers of change? In the first part of this research, regional trends in flood quantiles are assessed across Europe as a function of their return period, using a non-stationary regional flood frequency approach. Results show dependency of flood trends on their return period in all regions except north-eastern Europe. In the second part, a data-based approach for the attribution of flood changes to atmospheric, catchment and river drivers at the catchment scale is developed and applied to a case study in Upper Austria, where flooding has become more intense during the last 50 years. Flood trends here are attributed to long-term changes in extreme precipitation. Finally, the attribution approach is extended to the regional scale and used to assess the contribution of climatic drivers to the observed trends in flood quantiles at the European scale. Findings show that extreme precipitation caused changes in both small and big floods in north-western Europe. Antecedent soil moisture is the main contributor to changes in the median flood in southern Europe, while the contribution of the two drivers to changes in larger floods are comparable. In eastern Europe, snowmelt drives changes in both the median and the 100-year flood. These results provide an improved understanding of decadal changes in flood magnitudes at the regional scale and are useful for informing flood management strategies.
Troposphere Monitoring Based on Crowdsourced Smartphone GNSS Data
Authors: Pan Yuanxin , Kłopotek Grzegorz , Rothacher Markus , See Linda , Weinacker Rudi , Sturn Tobias , McCallum Ian , Navarro Vicente , Soja Benedikt
Published: February 2023

Global Navigation Satellite System (GNSS) is an essential tool for troposphere monitoring. Currently, GNSS meteorology depends mainly on the data from geodetic receivers of global or regional networks. However, these geodetic-grade GNSS stations are costly, and thus cannot be densely deployed, especially in less developed regions. Since the release of the Android 7 operating system in 2016, Android smartphones can be used to collect raw GNSS data. Considering that nowadays there are about 3 billion Android smartphones worldwide, a smartphone GNSS data crowdsourcing campaign was launched on March 17th 2022 as a part of the CAMALIOT project. About 5 TB of raw GNSS observations were collected around the world by more than 12 thousand users of the CAMALIOT Android application. In this contribution, we highlight the results related to the dedicated pipeline developed to process the crowdsourced smartphone GNSS data. Firstly, all the collected data were classified by a machine learning-based model to disregard observations of low quality. It was found that only about 2% of the collected data could potentially be used for troposphere delay estimation. The high-quality observations were then processed in the relative-positioning mode by forming baselines with the nearby geodetic stations. Several crowdsourced data sets were used to demonstrate that the zenith wet delays (ZWD) derived from smartphone data could achieve an accuracy of better than 10 mm. However, uncalibrated phase center variations of the smartphone antennas and multipath errors are still the main limitations to further improve the ZWD estimation. Overall, our study indicates that crowdsourced smartphone GNSS data is promising to densify the existing GNSS networks in terms of troposphere monitoring.
Monitoring soil status in an irrigated saline reclaimed marsh area in SW Spain using multi-receiver electromagnetic induction sensing and inversion
Authors: Ramos Mario , Farzamian Mohammad , Gómez Flores José Luis , Vanderlinde Karl
Published: February 2023

Multi-receiver electromagnetic induction (EMI) shows increasing potential for effective depth-specific monitoring of shallow soil properties as EMI sensors become available that provide simultaneous apparent electrical conductivity (ECa) measurements for small depths of exploration (DOE). Inversion of such ECa data results in more detailed soil profile EC estimates that can provide a completer understanding the soil hydrology and chemistry near the surface (<1 m depth). We demonstrated this by monitoring the soil status weekly at eight measurement locations in an irrigated cotton field in a saline reclaimed and tile-drained marsh area in SW Spain using a multi-receiver EMI instrument that provided ECa for 12 different DOEs. Soil water content and water table depth and conductivity were monitored at the eight locations. Inversion of the ECa data at the eight locations yielded characteristic EC profiles that depended on soil water content, irrigation and salt leaching, and water table depth. A depth-specific correlation analysis of the EC profiles and their first derivative elucidated the depths where the correlations were strongest and for which the best estimates of water content and water table depth and salinity could be obtained. The established relationships were then used to estimate these properties along two transects that contained each four of the monitoring locations. This approach allowed the detection of areas where a shallow water table emerged during the irrigation season which led to topsoil and crop salinization and can therefore assist decision-making in soil, water and crop management in this area. AcknowledgementThis work is funded by the Spanish State Agency for Research through grant PID2019-104136RR-C21/AEI/10.13039/501100011033 and by IFAPA/FEDER through grant AVA2019.018.
Seasonal forecasting of drought and temperature extremes as part of the Copernicus Emergency Management Service (CEMS)
Authors: Acosta Navarro Juan Camilo , Toreti Andrea
Published: February 2023

Climate extremes can impact societies in various ways: from nuances in daily lives to full humanitarian crises. Droughts  are usually slow onset extremes but can be highly disruptive and affect millions of people every year. Warm temperature extremes (e.g. heat waves) can exacerbate droughts and their impacts and trigger a faster drought evolution. Combined drought and heat waves can lead to devastating consequences. For example, 2022 was a very active year in terms of drought or combined drought and heat waves, affecting particularly hard several regions of the world (e.g. Europe, China, southern South America and East Africa). In a context of risk management and civil protection, the use of operationally available seasonal climate forecasts can provide actionable information to reduce the risks and the impacts of these events on societies with different levels of development and adaptive capacities.  Within the Copernicus Emergency Management Service (CEMS), the European and Global Drought Observatories (EDO and GDO, respectively) provide real time drought and temperature extreme monitoring products freely available and displayed through two dedicated web services. Recent efforts have been targeting the optimal integration and use of multi-system forecasting products to enhance the early warning component of the service. This contribution provides an overview of first results in terms of  initial multi-model skill assessment of forecasts available through the Copernicus Climate Change Service (C3S). It also discusses future avenues to improve skill in regions with limited predictability, for example by applying physically-based sampling techniques.    
Effects of improved tidal mixing in NEMO one-degree global ocean model
Authors: de Lavergne Casimir , Rathore Saurabh , Madec Gurvan , Sallée Jean-Baptiste , Ethe Christian , Nasser Antoine
Published: February 2023

Internal tides power much of the observed small-scale turbulence in the ocean interior. However, few models include a comprehensive and energy-constrained parameterization of mixing by internal tides. Here we present the impacts of three different tidal mixing schemes in 1,000-year long simulations with the NEMO global ocean model at one-degree resolution. The first scheme (Simmons et al. 2004) includes local bottom-intensified mixing at internal tide generation sites and a constant background diffusivity. The second explicitly includes both local and remote tidal mixing (de Lavergne et al. 2020), with no background diffusivity. The third scheme is identical to the second but has the added contribution of trapped (subinertial) internal tides, known to be important in polar regions. The three simulations show broadly similar circulation and stratification but significant differences in ventilation timescales. Explicit representation of remote tidal mixing strengthens the AMOC, while inclusion of trapped internal tides increases deep convection around Antarctica.
Ocean variability beneath the Filchner-Ronne Ice Shelf inferred from basal melt rate time series
Authors: Nicholls Keith , Vankova Irena
Published: February 2023

We deployed multiple phase-sensitive radars (ApRES) on Filchner-Ronne Ice Shelf (FRIS) to measure and characterize variability in its basal melt rate under present-day climatic conditions.Sites along the western portion of the ice shelf show primarily seasonal variations, consistent with the propagation dynamics of seasonal dense water from the western FRIS front into the cavity.Fifteen years of melt rate estimates from instruments moored beneath the ice at sites further from the western Ronne Ice Front are remarkably uniform in that melting is bounded between 0 and 1 m/a throughout the record. Here, inter-annual melt rate variability is expressed as a suppression or delay in the arrival of a seasonal melt rate minimum, which can be understood in terms of inter-annual stratification changes and variable inflow pathways towards the western Ronne sites.Elsewhere in the cavity, along a direct flow pathway connecting the western FRIS front and the southwestern tip of Berkner Island, the lower frequency inter-annual signal is superimposed on a regular seasonal signal, with year-to-year melt rate variations as high as 1 m/a. Anomalously low summer sea-ice concentrations in front of the ice shelf, such as in 1998 and 2017, cause higher melting along this pathway with a year's delay.Long term mean ApRES melt rates agree with estimates from satellite data over eastern FRIS. However, the satellite estimates overstate the area of active basal freezing in the western part of the ice shelf. The temporal melt rate variability from the satellite estimates dramatically overstates the range of variability at both seasonal and inter-annual time scales and only one site, on the eastern Ronne Ice Shelf, shows any correspondence between the in-situ and remotely derived inter-annual variability.
The evolution of permeability with pressure and temperature in microfractured granite
Authors: Carbillet Lucille , Heap Michael , Baud Patrick
Published: February 2023

Measurements of permeability at high-pressure and high-temperature are critical to model and understand the behaviour and evolution of geothermal systems. To perform such measurements and provide constraints on the permeability of crustal rocks, we designed and tested a new apparatus.Our high-pressure, high-temperature permeameter consists of three independent parts: the permeant gas circuit, the confining fluid circuit, and the heating element. For each measurement, a cylindrical sample is placed between the up- and downstream platens, into an annular Viton jacket which is secured within the pressure vessel. A confining pressure can be applied to the sample by filling the void space between the vessel and jacket through the inlet with kerosene. The confining pressure can be increased up to 50 MPa using a high-pressure hand pump. The temperature of the system can then be increased from room-temperature to up to 150 °C using a heating mantle wrapped around the pressure vessel and connected to a control box. After the confining pressure and temperature have been applied to the system, the permeability measurement is performed by flowing nitrogen (the permeant gas) through the sample while monitoring the pressure differential between the upstream pressure transducer and atmospheric pressure downstream of the sample at different volumetric flow rates (the steady-state method), measured using the downstream flowmeter.Using this new experimental apparatus, the permeability of Lanhélin granite (from France) samples were measured. Cylindrical samples were prepared and thermally stressed (heated to 700 °C) to ensure that their permeabilities lie in the range that can be measured in our set-up (> 10-18 m2). Permeability measurements were then performed under confining pressures of 2, 5, 10, 15, 20, 30, 40, and 50 MPa at room temperature, 50, and 100 °C. Our results provide the evolution of the permeability of microfractured granite in various pressure and temperature conditions, which will serve to inform numerical modelling designed to explore the influence of in-situ conditions on fluid flow within a fractured geothermal reservoir.
An integration of digital twin technology, GIS and VR for the service of environmental sustainability
Authors: Wang Chen , Miller David , Gimona Alessandro , Nijnik Maria , Jiang Yang
Published: February 2023

A digital twin is a digital representation of real-world physical product, system, or process. Digital twins potentially offer a much richer capability to model and analyze real-world systems and improve environment sustainability.In this work, an integrated 3D GIS and VR model for scenarios modeling and interactive data visualisation has been developed and implemented through the Digital Twin technology at the Glensaugh research farm. Spatial Multi-criteria Analysis has been applied to decide where to plant new woodlands, recognizing a range of land-use objectives while acknowledging concerns about possible conflicts with other uses of the land. The virtual contents (e.g., forest spatial datasets, monitored climate data, analyzed carbon stocks and natural capital asset index) have been embedded in the virtual landscape model which help raise public awareness of changes in rural areas.The Digital twin prototype for Glensaugh Climate-Positive Farming was used at the STFC workshop 2021, GISRUK 2022, 2022 Royal Highland Show which provides an innovative framework to integrate spatial data modelling, analytical capabilities and immersive visualization.Audience feedback suggested that the virtual environment was very effective in providing a more realistic impression of the different land-use and woodland expansion scenarios and environmental characteristics. This suggests considerable added value from using digital twin technology to better deal with complexity of data analysis, scenarios simulation and enable rapid interpretation of solutions.Findings show this method has a potential impact on future woodland planning and enables rapid interpretation of forest and climate data which increases the effectiveness of their use and contribution to wider sustainable environment.
Surface Water Flood forecasting using reasonable worst case scenarios from ensemble rainfall forecasts
Authors: Maybee Ben , Birch Cathryn , Boeing Steven , Willis Thomas , Speight Linda , Porson Aurore , Shelton Kay , Pilling Charlie , Trigg Mark
Published: February 2023

Surface water flooding (SWF) presents a significant risk to livelihoods, which is projected to increase under climate change. However, forecasting the intense convective rainfall that causes most SWF on the temporal and spatial scales required for effective flood forecasting remains extremely challenging. National scale flood forecasts are currently issued for England and Wales by the Flood Forecasting Centre (FFC). The forecasts are well regarded amongst flood responders, although they feel they would benefit from more location-specific information.We have developed an enhanced, regional-scale surface water flood forecast system driven by post-processed ensemble rainfall forecasts. We apply a neighbourhood post-processing method to generate percentile-based reasonable worst case rainfall scenarios from the UK operational Met Office Global and Regional Ensemble Prediction System (MOGREPS-UK), a 2.2km horizontal resolution, convection-permitting operational ensemble system that provides forecasts at up to 5 days lead time. Enhanced surface water flood forecasts are then generated by conducting look-ups of meteorological inputs against catchment-level hydrological reference data from the national Environment Agency Risk of SWF mapping database. In this manner the likely severity of flooding associated with forecast rainfall events is assessed by reference to the driving hyetographs for local-scale hydrological modelling, which is available nationally.Evaluation of the forecasts is informed by both quantitative assessment and qualitative user feedback. We tested the new forecast system over Northern England over summer 2022 and held a co-development workshop with professional and volunteer flood responders, in which we presented participants with existing and new forecasts for recent case-study flood events. We found that responders would routinely use the enhanced forecasts if they were offered as a complement to existing operational provision, with the enhanced information having the strongest impact on decision making for severe, high impact flood events. Responders valued having access to more localised forecast information, which was viewed as useful for decision making, despite the necessity of accepting a higher degree of forecast uncertainty.We evaluated the SWF forecasts over a historical 10-year period for days with observed SWF events across Northern England and, to assess false alarms, we verified them against SWF forecasts produced using radar observations for several summers’ continuous daily forecasts. The method is effective at forecasting impacts from higher impact flood events, although still generally over-estimates the extent of affected areas. The results of quantitative skill assessment will form a key basis for determining future operational deployment across England and Wales, which we will discuss the feasibility of and requisite next steps.
From tree-tip to trunk-base: interplay of resistance to embolism formation and wood anatomy in two conifers
Authors: Savi Tadeja , Zambonini Dario , Zagudaeva Khristina , Rosner Sabine , Petit Giai
Published: February 2023

Efficient and safe water transport in plants depends on specific wood anatomical structures. Comparing the hydraulic vulnerability among tree species and individuals can be biased by differences in the sampling procedure resulting in unjustified conclusions. In fact, water-transporting conduits of the xylem widen from the tree-tip toward the base potentially influencing xylem vulnerability to embolism formation.The resistance to cavitation and embolism formation (hydraulic vulnerability curves) was empirically tested at different positions from the tree-tip to the trunk base in a mature Norway spruce and a silver fir tree. Anatomical analyses (conduit diameter, pit traits) were performed on the same material used for hydraulic measurements.Substantial intra-plant variation in xylem anatomy and vulnerability to embolism was observed in both species scaling with the distance from the apex. The P50 values (i.e. the water potential resulting in 50% loss of hydraulic conductivity) were about 3 MPa more negative at the tip than at the trunk base. Tracheid diameters and pit dimensions increased from the apex downwards, confirming the tip-to-base conduit widening. The highest variability of both anatomical and physiological traits was observed within the first 3 m from the apex. We propose a method for the prediction of drought vulnerability based on hydraulically weighed conduit diameter distribution.A clear pattern of anatomical traits’ variation along the longitudinal axes of the tree was observed, likely playing a role in the increase of vulnerability to embolism. In comparative studies, we thus recommend to standardize the sampling of material according to the distance from the apex.
Spectral analysis of groundwater level time series reveals hydrogeological parameters
Authors: Houben Timo , Di-Dato Mariaines , Siebert Christian , Kalbacher Thomas , Fischer Thomas , Attinger Sabine
Published: February 2023

Groundwater resources are heavily exploited to supply domestic, industrial and agricultural water consumption. Climate and societal changes and associated higher abstraction will alter the subsurface storage in terms of quantity and quality in currently unpredictable ways. In order to ensure sustainable groundwater management, we must evaluate the intrinsic and spatially variable vulnerability of aquifers in terms of water quality issues and the resilience of groundwater volumes to external perturbations such as severe droughts in connection with intensive irrigation. For this purpose, physically based numerical groundwater models are of great importance, especially on the regional scale. The equations applied in these models must be fed with the hydrogeological parameters: The transmissivity T and the storativity S.Both parameters are typically obtained through time consuming and cost intensive hydrogeological in-situ tests or by laboratory analysis of core samples from point information (drillings and wells), resulting in parameters with limited transferability to regional settings. Instead, we propose to determine the parameters by spectral analysis of groundwater level fluctuations using (semi-)analytical solutions for the frequency domain. We developed a fully automatized workflow, taking groundwater level and recharge time series together with little information about the geometry of the aquifer to derive T and S as well as tc (the characteristic response time). While the first two will be used for hydrogeological modelling, the latter can serve as an indication to assess the resilience of the groundwater system directly without additional modelling attempts. The methodology was tested with great success in simplified numerical environments and was applied to real groundwater time series in southern Germany. The response times and the storativities could be robustly estimated while the transmissivities inherit quantifiable uncertainties. Depending on the hydrogeological regime, the parameters represented effective and regional estimates.
Late Quaternary history of glaciations in the northern Kara Sea and Arctic Ocean iceberg drift in marine isotope stage
Authors: Spielhagen Robert F. , Martin Blumenberg , Jolanta Kus , Yaroslav Ovsepyan , Ekaterina Taldenkova , David Wangner , Marc Zehnich
Published: February 2023

We present new data from two long sediment cores obtained off the St. Anna and Voronin troughs on the northern continental margin of the Kara Sea (eastern Arctic Ocean). According to preliminary age models based on microfossil findings and grain size data, the cores cover the last ca. 150 kyr. Coarse-grained layers with common to abundant iceberg-rafted lithic grains (IRD) were deposited when ice sheets on the Kara Sea shelf had advanced close to the shelf break and ice streams developed in the deep troughs opening towards the eastern Arctic Ocean. Terrestrial data suggest that large ice sheets in the area developed in marine isotope (sub)stages (MIS) 6, 5b, and 4, while glaciation was restricted to the westernmost Kara Sea in the last glacial maximum (MIS 2) (Svendsen et al., 2004, Quat. Sci. Rev.). Our new data reveal details of the ice extent during individual glacial phases. They suggest that only in MIS 6 both troughs were filled with ice streams and that in the younger glacial phases regional differences of ice extent developed along the continental margin.In several layers, coal clasts up to 4 cm in size were found. We have obtained coal petrological and organic geochemical data of these particles and of coal grains found in other sediment cores from the deep-sea eastern Arctic Ocean and the Fram Strait area. The results reveal a certain variability of data (random vitrinite reflectance (VRr %), Rock-Eval hydrogen and oxygen indices, hydrocarbon biomarkers) even among samples from the same core, suggesting that the coal grains do not stem from one restricted area. Data clusters and comparison with published information on coals from circum-Arctic continents, however, allow a tentative discrimination of our samples. The coals from the northern Kara Sea area and the central Fram Strait show relatively high oxygen indices, in opposite to coals from the NE Greenland margin. The latter resemble coals from the Cretaceous/Tertiary basins on Svalbard and NE Greenland. Available stratigraphic data from the cores suggests that the layers with high coal particle abundances in deep-sea cores from the northern Kara Sea area, the central Fram Strait, and the NE Greenland margin were deposited in MIS 6. We conclude that during MIS 6 coal-bearing layers in the NE Greenland Wandel Sea Basin were eroded by an expanded North Greenland Ice Sheet and transported by icebergs southward along the adjacent continental margin. At the same time, icebergs breaking off from the large northern Eurasian Ice Sheet drifted from northern Siberia across the Eurasian Basin towards the central Fram Strait. Our results generally support the hypothesis of a cross-Arctic iceberg transport in MIS 6 but show that caution must be applied when conclusions are made on the sources of individual coal particles.
The Circular Economy of Water - Developing a Strategy to Transition to a Water Smart Society
Authors: McCarton Liam , O'Hogain Sean , Nasr Ahmed
Published: February 2023

Many countries have implemented universal metering, increased water tariffs, delivered comprehensive demand management campaigns and reduced mains water network leakage rates. The next frontier in innovation is implementing a Circular Economy of Water (CEW). This is where used water is reused (without treatment), recycled (with treatment) and/or valuable products embedded within the used water stream are recovered and reused within different processes. Understanding the potential to supplement mains water with fit for purpose water is critical to implementing a CEW. However, there are limited studies which quantify micro component household water use in Ireland and Europe. This study sets out to address this gap in knowledge. The results presented in the paper show that for every 100 L of potable mains water supplied daily, 28 L was flushed down the toilet, 22 L was used in the hot water system, 17 L was supplied to cold water taps for personal hygiene uses and 33 L was used in the kitchen.  By proving that water supplied is utilised by different micro-components of a domestic household and through quantifying the amount consumed by each micro-component, the author justifies the concept of fit for purpose water, where function governs quality. The authors propose a Circular Economy of Water hierarchy focused on Reduce, Reuse, Recycle and Recover. A detailed twelve-step strategy is suggested to facilitate this transition to a water smart society. 
Mixed-phase Multilayer Clouds in the Arctic: A Simulation Study using ICON
Authors: Wallentin Gabriella , Hoose Corinna , Achtert Peggy , Tesche Matthias
Published: February 2023

Multilayer clouds (MLCs), defined as individual, vertically overlapping clouds, are frequently occurring worldwide but have been far less studied than single layered clouds. Earlier studies have suggested a clear abundance of MLCs in the Arctic compared with the rest of the world and with data from the MOSAiC campaign in 2019-2020 we have classified multilayered clouds at a 52% frequency of occurrence. The microphysical interaction between these cloud layers is expected to be complicated, such as the seeder- feeder mechanism, and we thus employ a model to further investigate these clouds. 

Cases from the MOCCHA campaign in 2018 as well as the MOSAiC campaign in 2019-2020 have been selected for MLC occurrences. These cloud systems vary from vertically distinct layers with no potential of seeding (subsaturated layer of >3km) to a doubly layered system within the boundary layer with frequent seeding events. The structure of the former can be simulated at a coarse grid spacing, provided appropriate initial conditions and aerosol concentration, whilst the latter is highly dependent on initial and boundary conditions, resolution, and parameterisation for the boundary layer. 

Together with an analysis of the measurements on board of the ships, the ICON (ICOsahedral Non-hydrostatic) model was deployed. The simulations are run with refined nests down to 75 meters horizontal grid spacing in ICON-LEM. Initial and boundary data are supplied by both ICON Global and IFS. As the Arctic aerosol contribution is yet to be parameterised, we are further making use of the prognostic aerosol module ART (Aerosol and Reactive Trace gases) developed by KIT, set up specifically for cloud condensation nuclei activation for sea salt and sulfate. 
Various sensitivity experiments have been performed on these case studies including (i) sensitivity to microphysical parameters, such as CCN and INP parameterisation and concentration, (ii) sensitivity to horizontal and vertical resolution as well as (iii) initial and boundary condition impacts on resolving the cloud layers. Furthermore, the aerosol concentration has been scaled, in the existing parameterisations in ICON, to represent the measurements on site as well as prognostically run using ICON-ART. 

Preliminary results on the modelled multilayer cloud system highlight a high dependency on the initial and boundary data quality as well as domain resolution while the microphysics have a smaller impact on the formation and detailed structure of the multilayer cloud system.
Photoelectrons and spacecraft potential effects on SWA-EAS electron measurements on board the Solar Orbiter spacecraft
Authors: Stverak Stepan , Herčík David , Hellinger Petr , Nicolaou Georgios , Owen Christopher , Maksimovic Milan
Published: February 2023

Any spacecraft immersed into the solar wind builds up a non-zero electric potential with respect to the local environment by continuously collecting the charged particles from ambient plasma populations and emitting additional charged particle populations, namely photo-electrons and/or secondary electrons, from its surface materials. These newborn electrons of spacecraft origin as well as the electric fields induced in the vicinity of the spacecraft body by the so called spacecraft potential may in turn significantly distort the local plasma conditions and therefore affect any in-situ electron observations and thus potentially modify the derived electron properties. Here we present an observational analysis of these effects as seen by the SWA-EAS electron analyser in the variable plasma and electrostatic environment of the Solar Orbiter spacecraft. We provide some characteristic properties of these parasitic electron populations in order to later develop possible correction methods applied to the SWA-EAS measurements for deriving unperturbed ambient plasma properties. The analysis is performed on a statistical basis using a large set of SWA-EAS 3D electron velocity distribution functions and in comparison to other relevant in-situ measurements acquired namely by other two complementary on board plasma instruments – SWA-PAS and RPW.
A status report after a decade of remotely sensed Solar Induced Fluorescence (SIF)
Authors: Morfopoulos Catherine , Prentice Colin
Published: February 2023

Leaf fluorescence is a natural process by which chlorophyll pigments relax part of the electromagnetic energy they absorb in the form of electromagnetic energy of lower intensity. Chlorophyll fluorescence happens in the photosynthetic apparatus and is tightly linked to processes generating reduction power and energy to drive carbon assimilation. For more than 40 years, scientists measured plant photosynthesis using Pulse-Amplitude-Modulation (PAM) chlorophyll fluorometer, an apparatus where fluorescence is measured upon actinic illumination and saturating pulse of light to retrieve quantum yield for photosynthesis.A little more than a decade ago, a breakthrough in spatial earth observation occurred: using narrow band observations in the oxygen A-band, the first global Solar Induced Chlorophyll Fluorescence (SIF) measurements were obtained. For the first time, the scientific community had access to observations directedly linked to photosynthetic processes arousing high expectations to constrain carbon uptake by terrestrial vegetation.In this study we assess to what extend these expectations have been met though an extended literature review. In addition, as SIF measurements are also linked to the vegetation structure and how an emitted photon escape the canopy, we will discuss the influence of the canopy structure in SIF measurements. We will also compare SIF products from different platforms in term of fluorescence yield, which is the first step to evaluate photochemical yield.  Finally, we will discuss difficulties arising when comparing vegetation models simulations and SIF measurements.
3-D joint inversion of surface wave and receiver functions based on the Markov chain Monte Carlo
Authors: Ke Kuan-Yu , Tilmann Frederik , Ryberg Trond , Mroczek Stefan
Published: February 2023

Geophysical inverse problems (seismic tomography) are often significantly underdetermined meaning that a large range of parameter values can explain the observed data well within data uncertainties. Markov chain Monte Carlo (McMC) algorithms based on Voronoi cell parameterizations have been used for quantifying uncertainty in seismic tomography for a number of years. Since surface waves constrain absolute shear velocities and receiver functions (RFs) image discontinuities beneath receiver locations, joint inversion of both data types based on McMC become a popular method to reveal the structure near Earth's surface with uncertainty estimates. Joint inversion is usually performed in two steps: first invert for 2-D surface wave phase (or group) velocity maps and then invert 1-D surface wave and RFs jointly to construct a 3-D spatial velocity structure. However, in doing so, the valuable information of lateral spatial variations in velocity maps and dipping discontinuities in RFs may not be preserved and lead to biased 3-D velocity structure estimation. Hence, the lateral neighbors in the final 3-D model typically preserve little of the 2-D lateral spatial correlation information in the phase and group velocity maps. A one-step 3-D direct inversion based on the reversible jump McMC and 3-D Voronoi tessellation is proposed to improve the above issues by inverting for 3-D spatial structure directly from frequency-dependent traveltime measurements and RFs. We take into account the dipping interfaces according to the Voronoi parameterisation, meaning that back azimuth and incidence angle of individual RFs must be taken into account. We present synthetic tests demonstrating the method. Individual inversion of surface wave measurements and RFs show the limitation of inverting the two data sets separately as expected: surface waves are poor at constraining discontinuities while RFs are poor at constraining absolute velocities. The joint solution gives a better estimate of subsurface properties and associated uncertainties. Compared to two-step inversion which may produce bias propagating between two steps and lose valuable lateral structure variations, the direct 3-D direct inversion not only produces more intuitively reasonable results but also provides more interpretable uncertainties.
The seasonal teleconnections of the Indian Ocean Dipole to the North Atlantic region
Authors: Hempel Tim , Weisheimer Antje , Palmer Tim
Published: February 2023

The Indian Ocean Dipole (IOD) is a major source of seasonal climate variability in theIndian Ocean. This dipole has strong impacts on the Indian Ocean region and throughteleconnections can influence the seasonal climate of remote regions like the North Pacificand North Atlantic. A prominent example of this teleconnection from the IOD occurredin the winter 2019/2020, where the IOD was in a positive state. This influenced the stateand predictability of the Northern Hemisphere extratropics. Thus, a good understand-ing of the mechanism that transports information from the Indian Ocean to the NorthAtlantic is desirable. In this contribution we investigate the special teleconnection of thewinter 2019/2020 and analyse the transport mechanism.In model experiments with the OpenIFS from ECMWF we show that the NAO in thewinter 2019/2020 is influenced by the IOD and analyse the teleconnection mechanisms.We use hindcast ensemble model experiments of the DJF season 2019/2020 to analysethe behaviour of the IOD and its impact on the NAO. In the uncoupled OpenIFS the SeaSurface Temperature (SST) boundary conditions are perturbed in regions of importanceto the NAO (like the ENSO region and the Indian Ocean). With these perturbations weidentify the relative importance of individual ocean regions to the state of the NAO inthe winter of 2019/2020.We contrast the experiments with the perturbed SST conditions to the operational ECMWFSystem5 forecast and ERA5. Experiments with the 2019/2020 SST’s in the In-dian Ocean (with other boundary conditions set to climatology) reproduce many of theobserved atmospheric 2019/2020 features. In contrast, experiments with SST’s in thePacific show very different patterns to the observed 2019/2020 ones.We identify eddy-mean-flow interactions as a mechanism that connects and transportsinformation from the Indian Ocean to the North Atlantic. With Hoskins E-Vectors weshow that anomalous eddy activity during IOD events impacts the position and strengthof the Northern Hemisphere extratropical jet. This interaction provides a teleconnectionmechanism in addition to the Rossby-wavetrain discussed in other studies.
Analysis of changes in long-term mean annual discharge in Slovakia
Authors: Jeneiova Katarina , Poorova Jana , Danacova Zuzana , Melova Katarina , Kotrikova Katarina
Published: February 2023

As the climate change and the research surrounding it intensifies, the assessment of the hydrological regime for the decision making processes also gains significance, as the design values are directly used for example for floods and droughts management.In this contribution we have analysed changes in the long-term mean annual discharges at 113 water gauging stations with long term observations in the period 1961-2020 over different time periods. To identify potential changes in the hydrological regime, the analysis was focused on the comparison of the 10, 20, 30, 40, 50-year long moving averages of the long-term mean annual discharges in the period 1961-2020 in comparison with the 1961-2000 reference period currently used in Slovakia for calculation of design values.The results point out that the new reference period to be used for calculating design values in Slovakia should include the time period after the year 2000, but to determine its precise length, more detailed analysis, especially in the area of the low flows, is needed.Acknowledgement: This work was supported by the Slovak Research and Development Agency under the Contract no. APVV-20-0374.
How are atmospheric blockings represented in a dry general circulation model with wave energy just as powerful as in the observations?
Authors: Deshmukh Vinita , Rivière Gwendal , Fromang Sébastien
Published: February 2023

Atmospheric blocking can be described as a large-scale stationary or quasi-stationary circulation anomaly that blocks the mean westerlies. Blocking often triggers extreme temperature events like heat waves or cold spells. However, dynamical processes leading to the formation, maintenance, and decay mechanisms of blocking are still not well understood.Moist processes have recently been proven to play a significant role in the formation and maintenance of blocking. However, it is unclear if moist processes generate special properties in the blocking life cycle that cannot be represented by dry dynamics or if they are just there to inject extra energy into the atmospheric disturbances. The following is the question we address in the present study: Is a dry dynamical model with climatology close to the observations capable of representing blocking characteristics correctly? The methodology relies on numerical experiments made with the new IPSL dynamical core called DYNAMICO, which enables high spatial resolutions. DYNAMICO is used here to analyze a long-term simulation in which the model forcing is designed to obtain a realistic climatology for a given season (perpetual winter in the present case). Blocking statistics like frequency of occurrence and duration are provided using two blocking detection algorithms and compared to the re-analysis dataset (ERA5). A focus is made on blocking onsets in the Euro-Atlantic sector. To highlight the differences in the processes leading to blocking onsets, backward Lagrangian trajectories seeded in the blocking regions are systematically computed and analyzed. Additional long-term simulations of the same dry model with the increased horizontal resolution are also analyzed following the same approach.
Scientific machine learning for speeding up distributed simulations – examples and failures for urban water systems
Authors: Löwe Roland , Adamsen Matthias Kjær , Aarestrup Phillip , Bauer Franca , Engsig-Karup Allan Peter , Grum Morten , Jeppesen Frederik Tinus , Mikkelsen Peter Steen
Published: February 2023

In this work we illustrate how scientific machine learning algorithms (SciML) can be used to facilitate the development of digital twins for urban drainage systems. Scientific machine learning integrates classical, modelling techniques from scientific computing that are based on first principles, with data-driven machine learning techniques. The main objective is to create models that are robust, fast to run and easier to integrate with data, while largely preserving the level of detail of the widely used hydrodynamic modelling approaches. This concerns both a detailed spatial representation of the drainage system in the models, and an accurate representation of the hydraulics.We present an initial approach that employs generalized residue networks for the simulation of hydraulics in drainage systems. The main idea is to train neural networks that learn how hydraulic states (level, flow and surcharge volume) at all nodes and pipes in the drainage network evolve from one time step to another, given a set of boundary conditions (surface runoff). The neural networks are trained against simulation results from a hydrodynamic model for a short time series, and achieve Nash-Sutcliffe model efficiency coefficients (NSE) in the order of 0.9 on a test dataset.The approach achieves simulation times that are in the order of 50 times faster than the corresponding hydrodynamic model. This enables an automated calibration of HiFi model parameters and real-time data assimilation routines, both of which are tuned manually in current practice. We will demonstrate how the runoff parameters in a distributed drainage model can be efficiently calibrated against water level observations, and how an Ensemble Kalman Filter setup can be tuned automatically.While our SciML setup for simulating drainage networks enables a range of new applications, its disadvantage are the initial training times in the order of 30 to 60 minutes for a system with approximately 100 drainage pipes. Many studies have demonstrated that machine learning approaches can be used to generalize across catchments if they consider physical system properties as an input or as part of the model architecture, and if they are presented with training data from different systems. Graph approaches are an obvious choice for the simulation of drainage systems and can be incorporated in the residue network setup. However, their architecture requires careful design to achieve an accurate simulation of the hydraulics, which is the subject of on-going research.
Modelling the near future air-quality over Central Europe
Authors: Prieto Perez Alvaro Patricio , Huszar Peter , Karlicky Jan
Published: February 2023

Air quality is not only dependent on emissions, but on climate and meteorology as well. This makes the study of the evolution of air pollution varying some of its drivers crucial. In this study, the present day and near future air quality in Central Europe is studied following RCP4.5 and RCP8.5 scenarios for the 2026-2035 and 2046-2055 decades, while considering present-day climate conditions. We assume that the climate changes a little while the main driver for air-quality changes in near future are the modified emissions. The emission input for the 2010-2019 decade were compiled using the Flexible Universal Processor for Modeling Emissions (www.fume-ep.org), and the two future decades are being prepared by scaling the present day emissions based on the mentioned RCPs. We are performing simulations using the Weather Research and Forecast with online chemistry version 4.0.3 (WRF-Chem) model and the Comprehensive Air-quality Model (CAMx). Several pollutants and meteorological variables will be studied and compared with observational data.