bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelling of Arabian Sea processes and investigation of Turbulent Kinetic Energy using Modular Ocean Model
Authors: Chauhan Rajesh , Behera Manasa , Balasubramanian Sridhar
Published: February 2023

Arabian sea (AS), a north Indian Ocean basin plays a significant role in the transfer of energy and moisture flux during the Indian summer monsoon. It is crucial to understand mixing in AS that affects ocean properties and subsequently the interaction between ocean and atmosphere. A huge amount of energy from the atmosphere in the form of winds is enforced to the ocean surface of Arabian Sea in summer monsoon which develops various large scale features such as Somali current, the great whirl, Socotra eddy and helps in churning the ocean layers. Thus in this study, standalone Ocean circulation model, Modular Ocean Model (MOM5) is used to study the dynamics and energetics of Arabian Sea in regional ocean domain. Regional AS with domain extent between 38 to 79⁰ E in longitude and 10⁰ S to 31⁰ N is chosen and open boundary condition is implemented at the southern and eastern part of the lateral boundaries for smooth exchange with the open ocean. Grid resolution is 0.25x0.25 ⁰ in horizontal and varies in vertical depth from 5m near surface to 500m near ocean bottom. Model is initialised from state of rest with an annual average Temperature and Salinity profile as background state and forced with 10 years climatology of daily average momentum flux from NASA JPL ECCO2 and heat fluxes from WHOI and precipitation from TRMM. At the lateral boundaries sea surface height anomaly is prescribed at 7 days interval to maintain the mass conservation. At lateral boundaries, vertical profiles of temperature and salinity are also prescribed at 5 days interval obtained from SODA. Model run is integrated for 10 years as spin up and then restarted for 5 years with instantaneous data from same source. The instantaneous 5-year output data is analysed to investigate the circulation and energetics in AS. It is observed that model very well represents the Somali current and south-eastward net water transport during summer monsoon and current reversal in winter monsoon with reversing winds and weak currents during boreal spring and fall. Salinity which plays dominant role in AS is also represented well in the model. Model produces a positive warm bias in the equatorial and south-western part of the domain which could be due to improper latent heat flux exchange. Investigation of Turbulent kinetic Energy (TKE) reveals that TKE is strong along Somali coast in summer monsoon and relatively weak in winter monsoon due to strong winds. Dissipation also shows strong signatures along Somali coast and quite strong features in equatorial region in winter monsoon. This indicates that AS is largely influenced by momentum flux exchange that in turn influences the energy budget.
Optimisation management of multi-purpose reservoir in the dry season: case study of Hoa Binh reservoir, Viet Nam
Authors: Nguyen Hai Yen , Ngo Le Long , Vu Minh Cat , Ngo Le An , Nguyen Thi Hien , Gebremedhin Tewelde Hagos , Peli Marco , Ranzi Roberto
Published: February 2023

Reservoir operation is a complicated problem to cope with regarding the complexities and the conflicts among the different stakeholders interest. The study presents the set of operating policies for a multi-purpose reservoir, case study of Hoa Binh reservoir, Viet Nam, focusing on two main objectives: Hydropower and Irrigation demand in the dry season, when the other main target, i.e. the flood control, is less crucial. In addition, another environmental objective under consideration for the dry season is the discharge needed to limit the salinity intrusion into the Red river delta surface water. This is a somehow novel objective to be taken into account when climate change scenarios, observed and projected sea level rise and saline intrusion are considered. The weight of this objective compared to the other ones can be set according to the policy adopted. The study is based on an evolutionary algorithm, namely Genetic Algorithm (GA) to find a Pareto optimal set under different scenarios. The results offer more flexible policies where the reservoir operator may see the trade-off between objectives to decide which is more suitable with the instant interest. Finally, it is shown that the GA model is promising to improve the performance of reservoir operation compared to strict regulations, which are now applied.
Data Assimilation and Subsurface Flow Modeling: Interactions between Groundwater and the Vadose Zone
Authors: Waldowski Bastian , Neuweiler Insa , Brandhorst Natascha
Published: February 2023

Reliable estimates of soil water content and groundwater levels are essential in evaluating water availability for plants and as drinking water and thus both subsurface components (vadose zone and groundwater) are commonly monitored. Such measurements can be used for data assimilation in order to improve predictions of numerical subsurface flow models. Within this work, we investigate to what extent measurements from one subsurface component are able to improve predictions in the other one.For this purpose, we utilize idealized test cases at a subcatchment scale using a Localized Ensemble Kalman Filter to update the water table height and soil moisture at certain depths with measurements taken from a numerical reference model. We do joint, as well as single component updates. We test strongly coupled data assimilation, which implies utilizing correlations between the subsurface components for updating the ensemble and compare it to weakly coupled data assimilation. We also update soil hydraulic parameters and examine the role of their heterogeneity with respect to data assimilation. We run simulations with both a complex 3D model (using TSMP-PDAF) as well as a more simplified and computationally efficient 2.5D model, which consists of multiple 1D vadose-zone columns coupled iteratively with a 2D groundwater-flow model. In idealized settings, such as homogeneous subsurface structures, we find that predictions in one component consistently benefit from updating the other component.
Sharing knowledge, skills and things: How institutes can benefit from centralised fieldwork management
Authors: Miesen Floreana , Ballu Aurélien
Published: February 2023

Planning fieldwork can be overwhelming and time consuming, especially for those who have never done it before, such as early stage PhD or undergraduate students. At the first day of a fieldwork, it is not uncommon to already be exhausted from extensive logistics management, selection and acquisition of adequate equipment and understanding regulations. Not having had the time or assistance to properly learn how to use a field instrument may impact the quality of collected data. Lone, inexperienced fieldworkers in difficult terrain may be confronted with additional safety challenges.We present ideas for institutional frameworks that support researchers in their fieldwork and share experience from our work as fieldwork technicians at the Institute of Earth Surface Dynamics, University of Lausanne. We suggest that many fieldwork-related resources can be shared across research groups and demonstrate how we provide centralised support to researchers and students in the management of their fieldwork goals, equipment and logistics.Institute-wide digital libraries managing field and safety equipment can be a useful and sustainable tool to avoid unnecessary double purchases across research groups and to re-use equipment after a project has finished. Streamlining the maintenance, repair, acquisition and improvement of equipment under one shared budget decreases the financial burden on individual research projects and groups. Dedicated technical staff can advise which field equipment best serves its purposes in the framework of the research question and provide innovative support for new instrumentation design. Centralising training on using the field equipment in a safe way not only improves the quality of the field data, but also makes sure that this knowledge is not lost in the short-term turnover of PhD projects.We further show that safety should always be considered in fieldwork planning and that institutes should provide comprehensive guidelines for this. Safety training and advice on risk assessment adapted to various fieldwork settings should be offered and institute members should be encouraged to regularly refresh their training. Finally, accompanying researchers and students directly to the field does not only avoid risky lone working, but can provide external, more technical expertise that can benefit the quality of the fieldwork outcome.
Long-term physiological insights of cone production as related to carbon isotope fractionation in stone pine forests of northern Spain
Authors: Shestakova Tatiana A. , Sin Ester , Voltas Jordi
Published: February 2023

Variation in life-history and ecophysiological traits has key ecological significance in plants, in which environmental changes play a central role throughout their life cycles. Stone pine (Pinus pinea L.) is one of the most characteristic species of the Mediterranean basin that is able to grow under harsh, limiting conditions and is typically defined as a masting species. Considering the high economical value associated with edible nut production, the masting habit of stone pine has been a main concern for forest management of the species. Here, we investigate the masting mechanism through characterization of temporal changes in tree ring-width (TRW), ecophysiological (cellulose Δ13C and δ18O) and cone yield patterns for five monospecific stands in north-central Spain. The regional positive (r = 0.41, SE = 0.25) and negative (r = –0.89, SE = 0.49) relationships involving tree growth vs. Δ13C and δ18O, respectively, suggest drought impairing carbon uptake via stomatal regulation for water saving occurring in the area during the period of 1960–2016. Increasingly positive relationships between TRW and Δ13C indicate intensifying impacts of drought on tree performance over time. By analyzing Δ13C–yield interannual dynamics, we found variable coupling of cone production with leaf-level gas exchange during the 4-year reproductive cycle of the stone pine. Particularly, the strongly positive relationships between Δ13C and yield with a 3-year lag, corresponding to strobili development and pollination, vanished and became non-significant in the recent decades. Thus, weather conditions during conelet emergence are not driving anymore cone production, which initially was sink-limited. In contrast, the relationships between Δ13C and a 1-year lagged yield, i.e. when cone enlargement and seed maturation occur, largely increased over the study period running from nearly zero (1960–1989 period) to above 0.50 (1987–2016 period) indicating a recent source limitation of reproduction driven by a harsher climate. Our results provide evidence that, although cone yield does not impose a penalty on aboveground biomass increments, it is becoming progressively limited by warming-induced effects of drought on tree ecophysiological performance.
Magnetic field spectra of ICMEs observed by Parker Solar Probe and Solar Orbiter
Authors: Good Simon , Rantala Oskari , Jylhä Anna-Sofia , Chen Christopher , Kilpua Emilia
Published: February 2023

A statistical study of magnetic field power spectra in interplanetary coronal mass ejections (ICMEs) observed by Parker Solar Probe and Solar Orbiter has been performed. The ICMEs had characteristically low proton beta, with values well below unity in all cases. The spectral index was typically near –5/3 and radially invariant in the inertial range, similar to solar wind near the heliospheric current sheet, and steepened to values below –3 in the kinetic range. The break frequency between the inertial and kinetic ranges evolved approximately linearly with radial distance and was closer in scale to the proton inertial length than the proton gyroscale. Magnetic compressibility was invariant with radial distance, in contrast to the solar wind generally. Removal of the background flux rope field gives spectra with shallower slopes at low frequencies (i.e. large spatial scales) and reveals shorter correlation lengths in the magnetic field.
Transport of bacteria, bacteriophages, and extracellular DNA as surrogates for pathogens and antibiotic resistance genes in a karst aquifer (Gallusquelle, South-West Germany)
Authors: Serbe Rebecca , Schiperski Ferry , Stelmaszyk Lara , Stange Claudia , Scheytt Traugott
Published: February 2023

Karst aquifers are vulnerable to contaminations due to their specific characteristics which allow for a rapid recharge and high velocities within the saturated zone. Contaminants such as pathogenic bacteria, viruses, and antibiotic resistance genes (ARG) can enter the groundwater and reach springs at high concentrations (Auckenthaler et al., 2002). This poses a potential threat, especially considering that drinking water treatment is less effective against microbial contaminations (Auckenthaler & Huggenberger, 2003) or missing, particularly in developing countries. Potential input of such contaminants is related for example to spills and leaks of waste water or application of manure. Many small-scale laboratory studies have been performed to understand the mobility of virus and bacteria, yet only little is known from large scale field tracer tests.We performed tracer tests using different non-pathogenic bacteria, bacteriophages, and extracellular DNA as surrogates for pathogens and ARGs together with uranine within the catchment of the Gallusquelle karstic spring. The average flow velocities in the groundwater system were about 30 and 87 m/h during our tracer tests. Tracers were injected as instantaneous input (10 minutes input time). Periodical sampling for the biological tracers started with the first detection of uranine about 80 to 90 hours after injection. Bacterial and eDNA tracers were analysed using qPCR methods while bacteriophages were additionally analysed using a culture-based method (plaque assay) to count active phages. First data indicates that all tracer materials were successfully injected into the groundwater and detected at the Gallusquelle spring. Results of the first tracer test suggest that all used tracer materials were transported over at least 3 km within the system. Furthermore, active bacteriophages of the second tracer test were transported over 9 km from a stormwater detention basin to the spring within 90 hours. 1D-transport modelling revealed much lower mass recovery for these active phages compared to the soluble tracer uranine (about 1% as maximum compared to approximately 31% for uranine). Auckenthaler, A., Raso, G. & Huggenberger, P. (2002): Particle transport in a karst aquifer: natural and artificial tracer experiments with bacteria, bacteriophages and microspheres. Water Sci. Technol., 46, 131-138Auckenthaler, A. & Huggenberger, P. (2003): Schlussfolgerungen und Empfehlungen. In: Auckenthaler, A. & Huggenberger, P. [eds.]: Pathogene Mikroorganismen im Grund- und Trinkwasser. Birkhäuser Verlag, Basel, 184 S.
SEVAN European particle detector network for the atmospheric, solar and space weather studies
Authors: Karapetyan Tigran , Chilingarian Ashot , Sargsyan Balabek
Published: February 2023

Experiments during recent years with SEVAN detectors on mountain tops in Armenia, Slovakia, and Bulgaria reveal the broad potential of SEVAN detectors; The SEVAN detector on Lomnicky Stit (Slovakia) measured the largest thunderstorm ground enhancements (TGE), with particle fluxes exceeding the background 100-times. With muon and gamma ray fluxes, the maximum values of the potential difference in thunderclouds were measured, equal to 350 MV at Mt. Aragats, and 500 MV at the sharp peak of Lomnicky Stit. In Nov 2019, SEVAN detectors were installed at DESY (Hamburg and Zeuthen sites). Fluxes of electrons, photons, and muons and weather parameters are continuously monitored at all sites (at different latitudes, longitudes, and altitudes). To fully exploit the scientific potential of the SEVAN detectors, in 2023 is planned to install a new detector in the Umwelt-Forschungs-Station (UFS, Schneefernerhaus, 2650 m asl) near the top of the Zugspitze (2962 m), a site with a long history of atmospheric research. The new SEVAN module will be compact (SEVAN-light), and will enable the energy spectra measurements in the range from 0.3 to 50 MeV, allowing unambiguously separating Radon progeny gamma radiation from runaway electron-photon avalanches.
Untapping the potential of geostationary EO data to understand drought impacts with XAI
Authors: Kraft Basil , Duveiller Gregory , Reichstein Markus , Jung Martin
Published: February 2023

Ecosystems are affected by extreme climate conditions such as droughts worldwide but we still lack understanding of the involved dynamics. Which factors render an ecosystem more resilient, and on which temporal scales do weather patterns affect vegetation state and physiology? Traditional approaches to tackle such questions involve assumption-based land surface modeling or inversions. Machine learning (ML) methods can provide a complementary perspective on how ecosystems respond to climate in a more data-driven and assumption-free manner. However, ML depends heavily on data, and commonly used observations of vegetation at best contain one observation per day, but most products are provided at 16-daily to monthly temporal resolution. This masks important processes at sub-monthly time scales. In addition, ML models are inherently difficult to interpret, which still limits their applicability for process understanding.In the present study, we combine modern deep learning models in the time domain with observations from the geostationary Meteosat Second Generation (MSG) satellite, centered over Africa. We model fractional vegetation cover (representing vegetation state) and land surface temperature (as a proxy for water stress) from MSG as a function of meteorology and static geofactors. MSG collects observations at sub-daily frequency, rendering it into an excellent tool to study short- to mid-term land surface processes. Furthermore, we use methods from explainable ML for post-hoc model interpretation to identify meteorological drivers of vegetation dynamics and their interaction with key geofactors.From the analysis, we expect to gather novel insights into ecosystem response to droughts with high temporal fidelity. Drought response of vegetation can be highly diverse and complex especially in arid to semi-arid regions prevalent in Africa. Also, we assess the potential of explainable machine learning to discover new linkages and knowledge and discuss potential pitfalls of the approach. Explainable machine learning, combined with potent deep learning approaches and modern Earth observation products offers the opportunity to complement assumption-based modeling to predict and understand ecosystem response to extreme climate.
High-resolution carbon, oxygen and magnesium isotope chemostratigraphy of the Kuibis Subgroup, Nama Basin
Authors: Paula-Santos Gustavo , Kasemann Simone , Bowyer Fred , Trindade Ricardo , Babinski Marly , Wood Rachel , Leme Juliana
Published: February 2023

The Kuibis Subgroup (~551- <547.36 Ma) in the Nama Basin records an important fauna assemblage change during the Ediacaran. Current models support a transition from a more diverse ‘White Sea’ biotic assemblage to a less diverse ‘Nama’ biotic assemblage, for which the drivers remain unresolved. In spite of this decrease in diversity, the Nama assemblage hosts the first appearance of metazoan biomineralization in the geologic record. High resolution chemostratigraphic data are required to globally anchor the timeline of Earth System changes leading to this innovation of life. In order to track these changes at high-resolution, we performed a sampling campaign of Namibian cores from the ICDP project ‘Geological Research through Integrated Neoproterozoic Drilling: The Ediacaran-Cambrian Transition’ (GRIND-ECT), which focuses on terminal Ediacaran stratigraphy of the Witputs and Vioolsdrif sub-basins of southern Namibia. Here we present new Carbon and Oxygen isotope data for carbonate rocks of the Kuibis Subgroup retrieved from drill core 1G. This core records an approximately 200 m-thick succession of mixed carbonate-siliciclastic sedimentary rocks of that unit. Both dolostones and limestones within the lowermost 100 m display negative δ13C values between -5 and 0 ‰, consistent with laterally-correlative outcrop data that record the Basal Nama Excursion (BANE). The oxygen isotope profile recorded in core 1G is also very distinctive throughout the BANE. It starts with a negative shift of the δ18O values from -5 to -15 ‰, which then progressively increase to values around -12 ‰. The uppermost 100 m of core 1G display a gradual increase in δ13C values that reach +5 ‰ and are accompanied by increasing δ18O values that approach -10 ‰. The 0 ‰ crossing point (carbon isotope value) occurs at ~90 m depth, below strata that confidently record the first appearance of fossils of biomineralizing animals. Magnesium isotopic and paleontological data added to our high-resolution carbon isotope profile have the potential to refine the knowledge about the biological and environmental changes of this time period. 
Sensitivity analysis of criteria weights in geodiversity assessment of the Karkonosze National Park, Poland
Authors: Najwer Alicja , Ligmann-Zielińska Arika , Zwoliński Zbigniew , Jankowski Piotr
Published: February 2023

The geodiversity assessment is particularly important in the case of areas belonging to critical zones, especially in the mountain regions. Recognizing the parts of a territory that are the most diversified and vulnerable to changes is a crucial issue for management and planning of protected and conserved areas (PCAs). Karkonosze National Park (KNP) located in south-western Poland in the border area between Poland and the Czech Republic was chosen as a research area. KNP covers the northern slopes of the Karkonosze Mountains, the largest range of the Sudetes.The geodiversity assessment based on spatial multicriteria analysis (S-MCA) with crowdsourced data was conducted. The geodiversity of KPN was evaluated with weighted linear combination (WLC) technique basis on selected criteria: 1) lithology, 2) relief energy, 3) geomorphology, 4) land use/land cover, 5) soils, 6) mesoclimate, and 7) hydrography. The assessment input data comprised of seven environmental factor ratings and weights were obtained from 57 Earth science researchers worldwide. These data served as the bases for a joint assessment of geodiversity and then spatially explicit global sensitivity analysis (GSA). The Monte Carlo simulation was used to sweep through criteria weight space, where weights are expressed using probability distributions. Multiple output suitability maps were generated and summarized using: an average suitability map, a standard deviation uncertainty map, and a number of sensitivity maps. The results helped to identify highly geodiverse areas that are burdened by high uncertainty and then to investigate which specific abiotic component contribute to the uncertainty the most. This could be valuable in monitoring and management of PCAs and significantly contribute to improving the existing results of geodiversity assessments and some savings resulting from field work.In the case of the mountainous area - KNP, the geodiversity value is the most sensitive to the lithological and the geomorphological criteria map. None of the weightings proved influential, suggesting a high consensus in weighting the factors among the geo-questionnaire respondents. In the future, it is worth conducting further simulations, considering another S-MCA technique, such as Ordered Weighted Averaging (OWA).
Prompt response of glaciers on Novaya Zemlya to recent warm summers shown by CryoSat swath data
Authors: Haacker Jan , Wouters Bert
Published: February 2023

Glaciers distinct from the ice sheets melt quickly around the world. Rounce et al., 2023, recently projected (28±9) % glacier mass will be lost in 2100 compared to 2015 in the low-emission scenario SSP1-2.6. In our study, we focus on the observation of recent glacier mass change on Novaya Zemlya, Russian Arctic, using the SARIn altimeter CryoSat-2. Taking advantage of CryoSat-2's spatiotemporal resolution and a novel processor optimized for mountain glaciers, we show a prompt response to the surface temperatures modeled by the regional atmosphere model MAR. Prominent warm and high-melt years were 2013, 2016, and 2020, while 2014 featured lower surface temperature and melt than average. We discuss the potential drivers for those extreme years and furthermore exploit surface mass balance estimates to analyze the relative contribution of ice dynamics and surface processes to the observed mass loss acceleration, and regional variations therein.
Modelling the effect of Nature based solutions on urban heat island using the Local Climate Zone scheme in Weather Research Forecast model
Authors: Budhiraja Bakul , McKinley Jennifer
Published: February 2023

Urbanization causes modifications in the urban climate of a city due to increase in impervious fraction and lack of evapotranspiration. The rise of extreme heatwave events due to climate change is causing concern for the cities effected by the urban heat island. Europe Union has recommended using Nature based solutions as a solution for multiple urban issues including the mitigation of urban heat. The UPSURGE project aims to use nature-based solutions for regenerative development in five demonstration cities. The five cities are based in different climate zones, consists of single to multiple demonstration sites, and are deploying various Nature based solutions based on the key city challenges.  The cities include Belfast, Breda, Budapest, Maribor, and Katowice. The demonstration sites are being Co-designed with multiple stakeholders to address the local concerns, diversity of voices to encompass perspectives and include citizens to address the longevity of Nature based solutions. The static and mobile sensors are being deployed to build a baseline and measure the effect of Nature based solutions. The cities have selected Nature based solutions varying from green roof, green wall, raingardens, Miyawaki forest, agroecology community gardens, rewilded zones, climate arboretum, meadows, water gardens. The work aims to model the effect of different Nature based solutions on the canopy urban heat island. The urban parameterization of the cities is done using local climate zone classification scheme. The advanced research Weather Research Forecast model is used to model the canopy urban heat island during the heatwave of July 2022. The WRF model is run for 7 days on three domains, 10 km, 5 km and 1 km horizontal resolution using six hourly data from ECMWF. The performance of the model has been assessed by analysing temperature, wind speed, relative humidity and surface level pressure considering their effect on local urban heat stress. The results showcase the importance of using actual urban morphology values in Weather Research Forecast to accurately simulate near-surface variables. The Weather Research Forecast simulations shows the presence of urban heat island and depicts the effect of deploying the various Nature based solutions across cities.
Nitrogen cycling in forest soils under elevated CO2: response of a key soil nutrient to global change
Authors: Rumeau Manon , Mackenzie Rob , Carillo Yolima , Sgouridis Fotis , Reay Michaela , Ullah Sami
Published: February 2023

Forests under elevated atmospheric CO2 concentration as a result of climate change are expected to require more available nitrogen (N) to sustain the enhanced CO2 uptake for photosynthesis and C storage. Therefore, it is essential to evaluate how CO2 fumigation of forests will affect availability of N to trees. Main pathways to sustain the high N demand are increasing biological N fixation (BNF), increasing N turn-over and reducing N losses. The purpose of this research is to explore the effects of elevated CO2 on soil N cycling in a temperate forest under the Birmingham Institute of Forest Research (BIFoR) Free Air Carbon Dioxide Enrichment (FACE) facility. We hypothesize that under CO2 fertilization, trees will allocate more carbon belowground to enhance microbial activity resulting in an increase of all nitrogen fluxes (i.e. N mineralisation, N fixation and N gas emissions). Net mineralisation rates were measured in-situ every month over 10 months and gross mineralisation rates were measured in-situ in spring, summer and autumn using the 15N pool dilution method. BNF by free-living organisms was investigated using the 15N assimilation method and N2O production rates were measured using the 15N-Gas flux method. Net mineralisation was increased on average by 30% under elevated CO2, delivering an extra 24 kgN.ha-1.y-1, and by 80% during the budburst period (April). Gross ammonification and NH4+ immobilisation rates were also slightly higher under elevated CO2 by respectively 33% and 19%. Yet, nitrification, NO3 immobilisation and N2O emission rates were not affected, demonstrating that, ammonium and nitrate cycling responded differently to elevated CO2. In addition, under elevated CO2, soils were more concentrated in DOC, DON and ammonium (p<0.05). Soil respiration and fine root biomass were also significantly higher by respectively 25% and 40%. Together, these findings suggest that trees allocate more C belowground through a higher root production and exudation enhancing N mineralisation under elevated CO2. Yet, the effects of elevated CO2 on N cycling are focused on increasing soil NH4+ availability as NO3- availability, N2O emission and N2 fixation were not responsive to eCO2. Collectively, our results suggest that trees are able to control and shape the nitrogen cycling communities to cope with N limitation. Nonetheless, it is difficult to predict if that will be sufficient to delay or alleviate progressive nitrogen limitation under future climate.
Trait-based, spatial, and temporal variation in leaf temperature of tropical trees.
Authors: Manzi Olivier Jean Leonce , Wittemann Maria , Mujawamariya Myriam , Manishimwe Aloysie , Habimana Jacques , Dusenge Eric Mirindi , Zibera Etienne , Tarvainen Lasse , Nsabimana Donat , Wallin Göran , Uddling Johan
Published: February 2023

Current estimates of temperature effects on plants are usually based on air temperature (Tair), although it is well known that leaf temperature (Tleaf) can deviate considerably from Tair. In some studies, to overcome the problem of Tair often being a poor proxy of Tleaf, measurements of canopy temperature (Tcan) have been used instead. However, Tcan data do not capture the spatial variation in Tleaf among leaves with different thermoregulatory traits. This may be particularly problematic for highly diverse and heterogeneous tropical forest canopies. In this study, we used infrared thermometers to study Tleaf and Tcan in multispecies tropical tree plantations established at three sites along an elevation gradient from 2,400 m a.s.l. (17.1°C mean daytime temperature) to 1,300 m a.s.l. (24.0°C) in Rwanda.  Measurements of chlorophyll fluorescence were also conducted to study the photosynthetic heat tolerance of these species. Our results showed high Tleaf (up to ~50°C) and leaf-to-air temperature differences (ΔTleaf; on average 8-10°C and up to 24°C) of sun-exposed leaves. Both leaf size and stomatal conductance were important traits in controlling Tleaf. The Tleaf (and thus ΔTleaf) of sun-exposed leaves greatly exceeded the simultaneously measured values of Tcan (and ΔTcan). Photosynthetic heat tolerance partially acclimated to increased growth temperature; on average 0.31°C increase in heat tolerance per 1°C increase in growth temperature. Consequently, thermal safety margins were narrower for species at the warmer, lower-elevation sites. Our findings highlight the importance of leaf traits for leaf thermoregulation and show that monitoring of canopy temperature is not enough to capture the peak temperatures and heat stress experienced by individual leaves in diverse tropical forest canopies. They also suggest that tropical trees have limited abilities to thermally acclimate to increasing temperatures.Keywords: Canopy temperature, elevation gradient, fluorescence, heat tolerance, leaf area, leaf temperature, stomatal conductance, thermoregulation, tropical forest.
Operational detection of sargassum from sun-synchonous and geostionnary satellites
Authors: Sutton Marion , Stum Jacques , Steinmetz François , Jolivet Dominique
Published: February 2023

Since 2011, unprecedent massive landings of sargassum seaweed (Sargassum fluitans and Sargassum natans) have been observed along the shorelines of a huge area encompassing the Gulf of Mexico, the Caribbean Sea and West Africa,  having tremendous negative impacts over local communities.Seen as a natural resource in the development of blue economy downstream applications or as an environmental threat for risk assessment and coastal management, sargassum data requires to be monitored at large geographical and temporal scales but also at local and real time scales.With the development of floating algae indexes, the use of satellite observations is a key to answer these needs, as it allows to depict the abundance of sargassum and monitor their movements and trends at basin scale with wide swath sensors (MODIS-Aqua, OLCI Sentinel-3), and at local scale with high spatial resolution sensors (Sentinel-2, Landsat-8) and high temporal resolution (geostationary satellites GOES-16).Since 2018, with the initial support of ESA, CLS has been developing and operating an operational system to provide sargassum detection products from a range of 6 sun-synchronous satellites in real time, using wide swath (MODIS, OLCI at 300m resolution) and high resolution optical sensors (MSI, OLI at 20m resolution).Since 2020, with the initial support of CNES, HYGEOS has been developing a novel processing of geostationary satellite data on ABI sensor on board GOES-16 that allows to extend the satellite coverage over one day thanks to its 10-minute temporal resolution.In the frame of the SODA project of the Copernicus Marine Service Evolution Program https://marine.copernicus.eu/about/research-development-projects/2022-2024/soda , the sargassum operational detections algorithms are being reviewed in the aim of providing the scientific research community and private downstream sectors with the best products adapted to each user needs.The presentation will highlight the first results of the SODA project, focusing on the improvement of the level 1 to level 2 sargassum processing on OLCI and MODIS and on the work done on the ABI sensor.
Fingerprint of CO2 and other gases on the greenhouse effect from direct satellite observation
Authors: Rentsch Chris , Myhre Gunnar
Published: February 2023

We use 19 years of continuous near-global land and ocean direct AIRS satellite measurements combined with detailed atmospheric radiative transfer modelling to demonstrate strong strengthening in the greenhouse effect caused by CO2 and detectable, but comparatively smaller strengthening, by CH4 and N2O. An increase in the outgoing longwave radiation is found in the 800-1000 cm−1 atmospheric window resulting from the Planck response to surface heating. The combined use of satellite measurements and the radiative transfer model also demonstrate that reductions in concentrations of prohibited ozone depleting substances have weakened the greenhouse effect in the spectral region where these gases absorb thermal infrared radiation. The strong greenhouse effect strengthening signal in the satellite data in the spectral region 710-720 cm−1 is a fingerprint of CO2 increase since we demonstrate that other factors could not cause such a robust spectral feature. We show how the spectral clear sky instantaneous change in TOA flux relates to the greenhouse gas radiative forcing over the 19-year period.
The Large-Scale Climate of Alaska - The Effects of the Pacific Decadal Oscillation on the Climate of Alaska
Authors: Heuer Jasper , Stuefer Martin , Hartl Lea
Published: February 2023

The climate of the state of Alaska is influenced not only by regional anthropogenic climate change, but also by the effects of large-scale ocean atmosphere systems like the Pacific Decadal Oscillation (PDO). Whereas positive anomalies in the PDO index coincide with warmer (sea surface) temperatures in the Gulf of Alaska and across the state, negative anomalies have the opposite effect. After analyzing the strength and direction of the correlation between the PDO index and the average temperatures in each of the 13 climate divisions of Alaska – both annually, as well as seasonally (DJF, MAM, JJA, and SON) – it becomes apparent, that the PDO affects the southern coastal and Panhandle regions much stronger than the Interior and North Slope. Over the course of a year, the correlations are strongest during the winter months, decrease during the spring and summer, only to increase again in the fall. Since the effects of large-scale circulations such as the PDO are changing under the influence of natural and anthropogenic climate change, reliable predictions on the future of the Alaskan climate are extremely complicated. In the future, further analysis is needed to support policy makers in their efforts to help adept the state’s ecosystems and economies to the changing climate.
Measures in Fundamental Physics within the Galileo for Science (G4S_2.0) project using the data of the Galileo Satellite Constellation
Authors: Visco Massimo , Di Marco Alessando , Sapio Feliciana , Lucchesi David , Cinelli Marco , Fiorenza Emiliano , Lefevre Carlo , Loffredo Pasqualino , Lucente Marco , Magnafico Carmelo , Peron Roberto , Santoli Francesco , Gatto Natalia , vespe francesco
Published: February 2023

Within the G4S_2.0 (Galileo for Science) project, funded by the Italian Space Agency (ASI), two activities in the field of Fundamental Physics are under investigation and development: a new measure of the Gravitational Red Shift (GRS) and a search for possible Dark Matter (DM) candidates in the form of domain walls. Both researches are based on data from high-accuracy clocks aboard the satellites.The GRS measurement exploits the two Galileo satellites DORESA and MILENA injected in 2014 into a wrong orbit characterized by a too high eccentricity. The corrected orbit, still has a relatively high eccentricity (about 0.16) suitable for gravitational measurements. Consequently, the clocks frequency of these two satellites is modulated with the changes of the Earth’s gravitational potential at the height of the satellite.The search for DM matter is done by looking for the expected rapid perturbations in on-board clocks when a structure like a domain wall crosses Earth’s orbit and the Galileo constellation.  If this occurs, on-board clocks would have to change their frequency relative to a reference clock on Earth.For both targets, a careful knowledge of the satellite’s position is required, to be obtained with a Precise Orbit Determination (POD) in which the main non gravitational perturbations, such as direct solar radiation pressure, are adequately modeled and accounted for. Furthermore, the clock data needs to be cleaned up by removing long-term drift and fast time jumps unrelated to the effects we want to measure.We will present the preliminary results obtained within these activities.
The Albian to Turonian record of IODP Site U1407 (SE Newfoundland Ridge)
Authors: Bornemann André , Friedrich Oliver , Moriya Kazuyoshi , Scher Howie
Published: February 2023

At IODP Site U1407 (SE Newfoundland Ridge, IODP Expedition 342) a 270-m-thick sedimentary succession of Cretaceous and Paleogene age has been recovered. The two holes U1407A and B contain the transition from the reef basement to fine grained (hemi-)pelagic marls at ~270 mCCSF. The basal, incomplete short-cores of these two holes revealed a number of shallow-water fossils such as gastropods, corals, rudists and larger foraminifera (orbitulinids; Norris et al., 2014) from the top of the reef. In addition, a well-developed Cenomanian-Turonian Boundary (CTB) with its typical black shale expression of the Oceanic Anoxic Event 2 is represented in the cores. Here, we present a high-resolution carbon isotope record of the 40-m-thick succession from the top of the reef to the bathyal CTB black shales. Beside the typical δ13C anomalies associated with the CTB we identified the decline of δ13C values related to the top of the Albian-Cenomanian boundary interval and the Mid-Cenomanian Event. We further present new biostratigraphic results based on calcareous nannofossils as well as 87Sr/86Sr isotope ages for the top of the reef analyzed on Orbitulina. These new data in combination with the identified, stratigraphically well-calibrated events allow for a detailed comparison with other mid-Cretaceous records around the world and provide new insights into the subsidence history of the western Atlantic margin off Newfoundland.Reference:Norris, R.D., et al. 2014. Site U1407. Proceedings of the Integrated Ocean Drilling Program, Volume 342, doi:10.2204/iodp.proc.342.108.2014.
Temperature retrievals from a ground-based, fully polarymetric, 50 GHz radiometer
Authors: Krochin Witali , Stober Gunter , Murk Axel , Albers Roland , Plüss Tobias
Published: February 2023

Continuous temperature measurements in the stratosphere (12-50 km) and the mesosphere (50-80 km) are crucial for the deeperunderstanding of the physical processes in the middle atmosphere and our understanding of the vertical coupling between thedifferent atmospheric layers. Several studies have shown the importance of atmospheric waves such as planetary waves, tides,and gravity waves, their propagation and breaking at these altitudes, and its effect on the global circulation.Investigating these effects requires long-term measurements with high temporal resolution and altitude coverage. Satellite datacovers the required altitude range but provides limited temporal resolution due to its fixed orbital geometry. Active measurementtechniques such as LIDAR are usually limited to nighttime and only a few instruments have daytime capability and thereforeare unsuitable for continuous observations. Ground-based microwave radiometry provides a robust observational method thatis independent of the daytime, almost independent of the weather conditions, and that permits to perform continuous soundingsfrom 20-60 km altitude.TEMPERA (TEMPErature RAdiometer) is a ground-based radiometer developed at the University of Bern in 2013. It measuresmicrowave radiation spectra from atmospheric oxygen in a range between 52 GHz and 53 GHz. Atmospheric temperature profiles can be retrieved from these spectra. In the last 9 years, the accuracy and performance of this instrument were continuouslyimproved. The latest version of TEMPERA has a temporal resolution of one measurement per 30 min and temperature profilescan be retrieved up to an altitude of about 50 km.The reason for the altitude limitation is the Zeeman effect, which occurs due to the interaction of the atmospheric oxygen withthe Earths magnetic field. The polarisation of atmospheric radiation affected by the Zeeman effect depends on the orientationof the propagation direction to the magnetic field. Therefore the altitude range for temperature retrievals could be furtherimproved by decomposing the measured radiation in its polarisation components. In addition, the inclusion of the Zeemaneffect in the retrieval algorithm provides the ability to retrieve the Earths magnetic field from measurements of atmosphericmicrowave emissions.The microwave group from the Institute of Applied Physics of the University of Bern, is currently developing a temperatureradiometer (TEMPERA-C), which is based on the former instrument (TEMPERA), but allows a fully polarymetric analysis ofthe atmospheric emission spectra. In my talk I will present the technical details of TEMPERA-C as for example the challengesin the calibration process. Furthermore I will present calibrated measurements of circular polarized atmospheric emissionspectra as well as temperature retrievals and discuss the effect of the Earth’s magnetic field on these measurements.
Global assessment of hydrological components using a seamless multiscale modelling system
Authors: Rakovec Oldrich , Kumar Rohini , Shrestha Pallav Kumar , Samaniego Luis
Published: February 2023

Our study provides a global assessment of water balance components accounting for the uncertainty in globally available precipitation products. This assessment is carried out consistently using a multiscale modelling framework established over more than 6000 GRDC river basins at various spatial resolutions (daily time step, period 1990-2019). The framework is based on the mesoscale Hydrologic Model (mHM; [1,2,3]) equipped with the multiscale parameter regionalization (MPR) scheme. All basins share the same parameterization and are driven with four different state-of-the-art meteorological products: ERA5 reanalysis [4], MSWEP [5], and deterministic EM-Earth v2 [6]. Additionally, the hydrological simulations are benchmarked against E-OBS [7] over Europe and against locally interpolated 1km gridded rain gauge dataset over Germany.Our results show that EM-Earth clearly exhibits the best streamflow performance across North and South America and Asia with respect to the other products. The MSWEP is the best product in Africa, where the overall model’s performance is rather poor. In Australia, MSWEP and EM-Earth have comparable skills. In Europe, the differences get narrower, although slightly better performance is seen for EM-Earth, with a median performance of 0.5 of daily KGE (N basins=2000), mainly due to correcting the under-catch error of rain gauges which is not considered, e.g. in E-OBS. Furthermore, when we zoom into a subset consisting of medium-sized 200 German basins, the in-house high-resolution meteorologic product clearly overperformed all global products, mainly due to better captured temporal correlation and smaller biases. On the other hand, ERA5 leads to very strong positive biases over German basins using standard parameterization. Finally, our study contributes to discussions on objective quantification of the optimal spatial resolution of hydrological studies. [1] https://doi.org/10.5281/zenodo.5119952[2] https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2008WR007327 [3] https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012WR012195[4] https://rmets.onlinelibrary.wiley.com/doi/10.1002/qj.3803[5] https://hess.copernicus.org/articles/21/589/2017/hess-21-589-2017.html[6] https://journals.ametsoc.org/view/journals/bams/103/4/BAMS-D-21-0106.1.xml[7] https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2017JD028200 