bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of Organic Nitrates in a European Temperate Forest
Authors: Andersen Simone , Dewald Patrick , Wüst Laura , Seubert Tobias , Schuladen Jan , Türk Gunther N. T. E. , Carpenter Lucy J. , Crowley John N.
Published: February 2023

Biogenic volatile organic compounds (BVOCs) are to a great extent oxidized by NO3 radicals at night leading to the formation of organic nitrates and secondary organic aerosols (SOA), which have an impact on human health and air quality. One of the focus points of the ACROSS (Atmospheric ChemistRy Of the Suburban forest) campaign, which took place in a temperate forest influenced by emissions from Paris over a period of 6 weeks during the Summer of 2022, was nighttime chemistry between NO3 radicals and BVOCs and its relative importance to daytime chemistry for organic nitrate formation.Measurements of total alkyl and peroxy nitrates and NO2 mixing ratios were performed using multi-channel cavity-ring-down spectroscopy (CRDS) with thermal dissociation inlets operated at different temperatures to distinguish between alkyl nitrates and peroxy-nitrates.NO2 were on average 1500 pptv across the entire campaign with an average diel maximum of 2200 pptv at nighttime and minimum of 800 pptv in the afternoon. Both total alkyl and peroxy nitrates showed a diel profile with average daytime maxima of 250 and 450 pptv, respectively, and average nighttime minima of 150 and 250 pptv, respectively.The relative contributions of day- and nighttime chemistry for generation of ANs will be assessed as will the lifetime of ANs in this environment and the efficiency of NOx conversion into organic nitrates.
Simulating spontaneous AMOC collapses with a Rare Event Algorithm
Authors: Cini Matteo , Zappa Giuseppe , Corti Susanna , Ragone Francesco
Published: February 2023

 Understanding the stability of the Atlantic Meridional Overturning Circulation (AMOC) and its future development under anthropogenic forcing is of key importance for advancing climate science. Previous studies have explored the stability of the AMOC by applying external perturbations in climate models, such as freshwater hosing to the North Atlantic Ocean. However, if the system is close to losing stability, the tipping of the AMOC may also spontaneously occur via internal coupled atmosphere-ocean variability. Here, we address this hypothesis - using an innovative approach - by studying the nature of a spontaneous collapse of the AMOC in an intermediate complexity climate model (PlaSIM coupled to the LSG ocean) featuring - under pre-industrial conditions - an apparently stable state. Excluding all possible external forcing elements (for example green-house gasses increase, water hosing, radiative forcing anomalies), significant AMOC slowdowns and collapses can be treated as extreme events solely driven by the chaotic internal atmospheric variability.  Facing this problem, we look for extreme AMOC slowdowns by applying a Rare Event Algorithm (Ragone, Wouters and Bouchet, 2018), which - via a selective cloning of the most interesting model trajectories -  allows a faster exploration of the model phase space in the direction of an AMOC decrease.After exploring the parameters of the rare event algorithm, we find a regime in which PLASIM/LSG shows an abrupt AMOC slowdown over a 20-years period to a substantially weakened state, which is unprecedented in the pre-industrial run. Stability analysis reveals that part of these slowdown states are actually collapsed, i.e. states around a much lower value of the AMOC that do not recover to previous values.This approach also enables us to isolate the atmospheric processes driving the AMOC slowdown, from the climate response to the weakened AMOC state. Interestingly, we find that the climatic response to internally-induced AMOC slowdowns shows strong similarities with the responses to externally forced AMOC slowdowns in state-of-the-art climate models  for what concerns temperature, wind, and precipitation changes. Looking at the mechanisms causing the AMOC weakening, instead, we find that zonal wind stress over the North Atlantic is the main driver of the AMOC slowdown, via changes in Ekman transport that affect salinity and deep convection in the Labrador sea. In this climate model, the repeated occurrence of this circulation anomaly for a few decades is sufficient to drive  an AMOC collapse without possibility of recovery on multi-centennial time scales.Overall, these results show that the methodology proposed here can be generally useful for other studies in Tipping Points since it introduces the possibility of collecting a large number of critical events that cannot be sampled using traditional approaches.  
Validation of a MAX-DOAS instrument-based cloud classification algorithm
Authors: Reischmann Lucas , Ziegler Steffen , Beirle Steffen , Kumar Vinod , Donner Sebastian , Wagner Thomas
Published: February 2023

A major challenge in Differential Optical Absorption Spectroscopy (DOAS) is the characterization of the light path. For the determination of the light path length, cloud conditions are essential. While instruments like a LIDAR/ceilometer provide information on cloud base height in zenith direction, it is often quite challenging to obtain information on cloud coverage in the line of sight of a Multi-Axes-DOAS (MAX-DOAS) instrument.In this study, we apply an existing cloud classification algorithm using combined information from the colour index and the O4 slant column density (Wagner et al., 2013) on spectra recorded by a MAX-DOAS instrument. In order to validate the algorithm, a MAX-DOAS with camera measurements of the sky conditions carried out at the Max Planck Institute for Chemistry in Mainz for several months. The results of the cloud classification algorithm are compared to the recordings of the cameras in order to analyse the performance of the algorithm.
When to Expect Rate-Induced Tipping in Natural and Human Systems
Authors: Ritchie Paul , Alkhayuon Hassan , Cox Peter , Wieczorek Sebastian
Published: February 2023

Over the last two decades, tipping points have become a hot topic due to the devastating consequences that they may have on natural and human systems. Tipping points are typically associated with a system bifurcation when external forcing crosses a critical level, causing an abrupt transition to an alternative, and often less desirable, state. However, the rate of change in forcing is arguably of even greater relevance in the human-dominated anthropocene, but is rarely examined as a potential sole mechanism for tipping points. Thus, I will introduce the related phenomenon of rate-induced tipping: an instability that occurs when external forcing varies across some critical rate, usually without crossing any bifurcations. First, I will explain when to expect rate-induced tipping. Then, using illustrating examples of differing complexity I will highlight universal and generic properties of rate-induced tipping in a range of natural and human systems.
Cumulative impact of farm dams on catchment water balance and streamflow dynamics at the regional scale. A numerical experiment using a distributed hydrological model.
Authors: Branger Flora , Bonneau Jérémie , Pouchoulin Sébastien , Sauquet Eric
Published: February 2023

Climate change increases the risk of water scarcity due to a higher probability of droughts and heat waves, even in temperate countries. A currently controversial adaptation strategy deployed by farmers is the multiplication of small dams to intercept water during the winter months (either from hillslopes or headwater streams), and store it through the summer months to secure irrigation and cattle watering. However, the impact of such practices on catchment water balance and streamflow dynamics is difficult to assess, because of the lack of reliable data but also the lack of models able to represent these devices. In the framework of the J2000 distributed hydrological model, we developed a simple component representing farm dams in mesoscale to regional scale catchments. The model was applied to the Rhône catchment in France (~ 100000 km²), using a database of known locations of farm dams to assess the impact of these dams on catchment water balance components and several streamflow dynamics indicators. Several scenarios were simulated, under present climate, according to various parameterizations such as absence / presence of dams but also varying the density and dimensions of the reservoirs, as well as their infiltration properties and drainage areas. The results show that the impact of such dams is potentially high, but is also highly dependent on the parameterization scenarios, thus confirming the need for more complete land and water uses databases.
The extraordinary March 2022 East Antarctica heatwave
Authors: Wille Jonathan ,   East Antarctica heatwave project
Published: February 2023

Between March 15-19th 2022, East Antarctica experienced an unprecedented heatwave with widespread 30-45° C temperature anomalies across the ice sheet. This record-shattering event saw numerous monthly temperature records being broken including a new all-time temperature record of -9.4 °C on March 18th at Concordia station despite March typically being a transition month to the Antarctic coreless winter. The driver for these temperature extremes was an unprecedently intense atmospheric river (AR) advecting heat and moisture deep into the Antarctic interior. The scope of the temperature records spurred a large, diverse collaborative effort to study the heatwave’s meteorological drivers, impacts, and historical climate context using an array of observations, models, and analysis techniques.  From these efforts, we present the followingTemperature observations and records
Meteorological drivers including tropically forced Rossby wave activity along with AR and warm conveyor belt dynamics
Radiative forcing impacts on surface temperatures and inversions
Surface mass balance impacts
Discussion of the AR impacts on isotope and cosmic ray measurements from Concordia station
AR influence on the Conger Ice Shelf disintegration
Event return time analysis
Implications on past climate reconstructions
Future event likelihood from IPSL-CM6 simulations
UPLFOW ocean bottom seismometers data: preliminary performance report
Authors: Tsekhmistrenko Maria , Diaz Roberto , Harris Katrina , Tilmann Frederik , Krüger Frank , Ferreira Ana , Miranda Miguel ,   UPFLOW Team
Published: February 2023

We present preliminary results from the UPFLOW (Upward mantle flow from novel seismic observations; https://upflow-eu.github.io/) project and associated large-scale amphibian experiment. The UPFLOW project, funded by the European Research Council (2021-2026), led a passive seismology large-scale experiment in the Azores-Madeira-Canary region starting in July 2021 and ending in September 2022. We recovered 49 (out of 50) OBSs deployed in a ~1,000×2,000 km2 area and with an average station spacing of ~150-200 km. Most instruments have three-component wideband seismic sensors (Trillium compact OBS version with a corner period of 120 s) and broadband hydrophones (type HTI-01 and HTI-04-PCA/ULF) with a corner period of typically 100 seconds. Three different designs of OBS frames were used LOBSTER, NAMMU and DUNE. We achieved data recovery rates of ~90-100% in 37 stations and ~50% in 6 stations, with only 7 stations being faulty, highly problematic or lost. We present various illustrative examples of seismic waveforms, spectrograms and data quality analysis from the recovered OBS data. Systematic probability power spectra density (PPSD) plots for all stations and over the whole deployment show a marked improvement in the quality of the long-period data (T>~30s) compared to previous experiments. We analyse the data performance as a function of the three models of OBS, recorder and seismometer types. Additionally, we present initial results from: (i) noise correlation analysis to quantify the clock skew during the deployment; (ii) estimation of horizontal component rotation angles from teleseismic data (body and surface waves); and, (iii) tilt and compliance analysis. Finally, we present an initial set of ~6000 multi-frequency body-wave travel time measurements generated with the UPFLOW OBS data and show a glimpse of preliminary body wave tomographic models built with this new dataset.
Arid occupation of south-eastern Arabia: A new Late Pleistocene site at Wadi Asklat, south-central Oman—dating and paleoenvironmental reconstruction.
Authors: Garba Roman , Meredith-Williams Matthew , Neuhuber Stephanie , Gier Susanne , Usyk Vitalii
Published: February 2023

The Arabian Peninsula was, up until recently, thought to have been depopulated during the more arid phases between MIS5 and Holocene interglacials, and in particular during MIS3 and MIS2. Within the last few years there have been five new sites dated to this arid phase, demonstrating that at the very least there were episodic occupation events on the Arabian Peninsula, and potentially refugial populations. The increasing number of sites potentially lends weight to the hypothesis for a more continuous refugial population on the Arabian Peninsula, as opposed to multiple-short lived events. The human adaptation to harsh environment during transition from humid period is a focus of this research project. Here we present preliminary dates from the newly recorded site at Wadi Asklat in Duqm, south-central Oman, where stratified lithic technology has been identified within a alluvial terrace sediment sequence. Two OSL samples at depth of 100 and 125 cm were taken to understand site chronology together with geomorphic processes. The paleoenvironmental samples were collected for palynological and pedological analyses. The preliminary clay mineral analysis identified palygorskite, illite, chlorite, smectite in layer at depth 90 to 110 cm suggesting a soil formation process. The lithic artifact at depth of 115 cm was preliminarily identified as Kombewa core with two bidirectional negatives made on crested flake. In addition, a several stratified sites have also been identified within the area, however except for the Wadi Asklat site these are at present undated. The association of many of the new sites with river terraces, including Wadi Asklat, indicate an important link between human activity and water which was no doubt heightened during arid phases. The results contribute to our knowledge of population dynamics and settlement patterns in this under-studied region of central Oman. The research is as a joint effort of ARDUQ expedition led by Archaeological Institute Prague (Czechia) and LARiO expedition led by La Trobe University Melbourne (Australia).
Estimating correlation lengths of aquitard hydraulic conductivity by inverse geostatistical modelling of a pumping test
Authors: van Leer Martijn , Zaadnoordijk Willem Jan , Zech Alraune , Griffioen Jasper , Bierkens Marc
Published: February 2023

Aquitards are common hydrogeological features in the subsurface and its properties are important for e.g. water resource management, subsidence, contamination transport and aquifer thermal energy storage. Typically pumping test are used to parameterize the hydraulic conductivity of aquitards. However, with analytical interpretation of pumping tests it is difficult to take spatial variability and uncertainty into account. Alternatively, core-scale measurements of hydraulic conductivity are used in geostatistical upscaling methods, for which their correlation lengths are needed. However, this information is extremely difficult to obtain. In this study we investigate whether a pumping test can be used to obtain the correlation lengths needed for geostatistical upscaling and  account for the uncertainty about heterogeneous aquitard conductivity. We generated random realizations from core scale data with varying correlation lengths and inserted these into a groundwater flow model which simulates the outcome of an actual pumping test. We selected the realizations which yielded a better fit to the pumping test data than the traditional pumping test result assuming homogeneous layers. Ranges of horizontal and vertical correlation lengths that fit the pumping test well are found. However, considerable uncertainty regarding the correlation lengths remains which should be considered when parameterizing a regional groundwater flow model.
Assessing and managing the risk of water quality contamination after wildfires: an example approach for Portugal
Authors: Nunes Joao Pedro , Parente Joana , Benali Akli , Dias Luis Filipe
Published: February 2023

Wildfires can change vegetation cover and soil properties, often enhancing surface runoff and sediment transport processes. The ash produced by these fires can also be mobilized and contaminate downstream water bodies with fine sediments, heavy metals, nutrients and organic carbons. Urban water supplies are usually taken from watersheds with natural vegetation cover to limit agricultural contamination; this makes these supply sources vulnerable to disruption after wildfires, an occurrence which might be infrequent but carry large consequences such as supply disruptions. Moreover, mobilized ashes can deposit in stream and reservoir beds and be resuspended for years after the fire, prolonging the disruption in time.Forest and water managers can take some steps to manage these risks, including preventive forest management planning and contingency planning for emergency interventions in the burnt areas themselves and at the treatment plants. However, the elements to quantify these risks are generally poorly quantified in most fire-prone watersheds. Fire regimes might be known, but the relationships between fire characteristics and impacts on water quality are difficult to assess without good datasets; and the costs and benefits of different mitigation approaches are usually not well understood. To further complicate matters, the impacts of wildfires on hydrology and sediment processes tend to vary significantly across climatic regions, making it difficult to transfer knowledge.This presentation will provide an overview of the issues surrounding the assessment of the risk of water quality contamination after wildfires. It will also provide an example on how this is being done in Portugal, through project FRISCO: Managing Fire-Induced Risks of Water Quality Contamination (FCT, ref. PCIF/MPG/0044/2018). The project, now in its fourth and final year, has (i) determined the most important fire and post-fire conditions leading to fire-induced contamination events, through a detailed analysis of a 20-year water quality database for over a hundred water supply reservoirs, linked with a concurrent atlas of fire severity; (ii) developed, together with water managers, a risk assessment index that can be used after a fire to inform managers on the need for further action; and (iii) is assessing multiple post-fire intervention options, from the biophysical and socioeconomic perspectives, to help inform managers on which actions they can take to address the issue. This project provides a blueprint on how these issues might be addressed by water managers in other fire-prone watersheds.
Strong ocean melting feedback during the recent retreat of Thwaites Glacier
Authors: Holland Paul , Bevan Suzanne , Luckman Adrian
Published: February 2023

The accelerating ice loss from Thwaites Glacier is making a substantial contribution to global sea-level rise, and could add tens of centimetres to sea level over the coming centuries. This ice loss is associated with rapid thinning and disintegration of the floating sections of Thwaites Glacier, and retreat of its grounding line. In this study, we use a high-resolution ocean model and a series of Digital Elevation Models of the floating part of Thwaites Glacier from 2011 to 2022 to simulate the evolution of sub-ice melting during this rapid retreat.The results show that the ice evolution induces a strong geometrical feedback onto melting. The ice thinning and retreat provide a larger melting area, thicker and better-connected sub-ice water column, and steeper ice base. This leads to stronger sub-ice ocean currents, increasing melting by ~50% without any change in forcing from wider ocean conditions. This geometrical feedback over just 12 years is stronger than the melting changes expected from century-scale changes in ocean conditions and subglacial meltwater input. The strength of this feedback implies that greenhouse gas emissions policy may have a very weak influence over future ocean-driven ice loss from Thwaites Glacier.
Insights into NOM quality changes by combination of easy designed experiments close to nature and monitoring using FT-ICR-MS
Authors: Herzsprung Peter , von Tümpling Wolf , Kamjunke Norbert , Lechtenfeld Oliver J.
Published: February 2023

Natural organic matter (NOM) is often still a black box considering its isomeric composition. From the analytical point of view the highest resolution of NOM can be achieved by Fourier-transform ion cyclotron resonance mass spectroscopy (FT-ICR-MS). This analytical tool generates elemental compositions of thousands of NOM components (molecular formulas, MFs) which can be extracted from aqueous samples (e.g., via solid phase extraction) and which are ionizable (e.g. via electrospray ionization). The comparison of NOM quality in waters of different ecosystems has generated useful insights about ecosystem-specific molecular differences. However, NOM is not an inert mixture of compounds and can undergo chemical changes by photochemical or microbial reactions or adsorptive fractionation. By following the relative intensity changes of single MFs during simple experiments close to nature or monitoring, elucidation of the reactivity of the underlying NOM compounds is possible.We have combined a photochemical degradation experiment close to nature with monitoring results from two German drinking water reservoirs with the perspective to disentangle photochemical and microbial reactions in the reservoirs. Bacterial induced transformations were widely excluded in the photo degradation experiment by filtration of the sample water before irradiation. During the reservoir monitoring, both microbial and photochemical reactions can be suggested from relative intensity differences of single MFs during lake stratification (between epi- and hypolimnion). MFs show intensity changes both in the photo experiment and in the lake monitoring are regarded as photo labile or photo products. Those MFs with intensity differences only in the lake monitoring can be regarded as microbial reactive.A great number of highly reactive MFs were found to be present in all samples of both the photo degradation experiment and the lake monitoring. MFs like C9H12O6, C10H14O6, C10H14O7, C11H16O5 were photo products, MFs like C20H16O14, C19H14O13, C18H12O12 were photo degraded. MFs like C10H10O7 and C9H10O7 could be suggested to be microbial products because they showed elevated intensity in epilimnetic waters but minor reactivity in the photo experiment.Our studies (1, 2, 3) provide the attempt to follow NOM reactivity by visualization of single MFs relative intensities versus time and / or space.1) Wilske, C.et al.,Water MDPI (2020) 12 (2).2) Herzsprung P. et al., Environ. Sci. Technol. (2020), 54, 13556-135653) Wilske C. et al., Water MDPI (2021), 13, 1703.
Benford's law in detecting rapid mass movements with seismic signals
Authors: Zhou Qi , Tang Hui , Turowski Jens M. , Braun Jean , Dietze Michael , Walter Fabian , Yang Ci-Jian , Lagarde Sophie , Abdelwahab Ahmed
Published: February 2023

Rapid mass movements are a major threat in populated landscapes, as they can cause significant loss of life and damage civil infrastructure. Previous work has shown that using environmental seismology methods to monitor such mass movements and establish monitoring systems offers advantages over existing approaches. The first important step in developing an early warning system for rapid mass movements based on seismic signals is automatically detecting events of interest. Though the approach, such as short-term average to long-term average ratio (STA/LTA) and machine learning model, was introduced to detect events (e.g., debris flow and rockfall), it is still challenging to calibrate input parameters and migrate existing methods to other catchments. Detection of debris flows, for instance, is similar to anomaly detection if we consider the seismic stations recording background signals as an overwhelming majority condition. Benford's law describes the probability distribution of the first non-zero digits in numerical datasets, which provides a functional, computationally cheap approach to anomaly detection, such as fraud detection in financial data or earthquake detection in seismic signals. In this study, seismic signals generated by rapid mass movements were collected to check the agreement of the distribution of the first digit with Benford's law. Subsequently, we develop a computationally efficient and non-site-specific model to detect events based on Benford's law using debris flows from the Illgraben, a Swiss torrent, as an example. Our results show that seismic signals generated by high-energy mass movements, such as debris flows, landslides, and lahars, follow Benford's law, while those generated by rockfall and background signals do not. Furthermore, our detector performance in picking debris-flow events is comparable to a published random forest and seismic network-based approach. Our method can be applied at other sites to detect debris-flow events without additional calibration and offers the potential for real-time warnings.
Prediction of Adverse effects of Geomagnetic storms and Energetic Radiation (PAGER)
Authors: Bianco Stefano , Shprits Yuri , Vasile Ruggero , Wutzig Michael , Wang Dedong , Burns Melanie , Haas Bernhard , Arber Tony , Bennett Keith , Santolik Ondrej , Kolmasova Ivana , Taubenschuss Ulrich , Liemohn Mike , van der Holst Bart , Forest Julien , Trouche Arnaud , Tezenas du Montcel Benoit
Published: February 2023

An update on our project aiming to provide space weather predictions that will be initiated from observations on the Sun and to predict radiation in space and its effects on satellite infrastructure. Real-time predictions and a historical record of the dynamics of the cold plasma density and ring current allow for evaluation of surface charging, and predictions of the relativistic electron fluxes will allow for the evaluation of deep dielectric charging. The project aims to provide a 1-2 day probabilistic forecast of ring current and radiation belt environments, which will allow satellite operators to respond to predictions that present a significant threat. As a backbone of the project, we use the most advanced codes that currently exist and adapt existing codes to perform ensemble simulations and uncertainty quantifications. This project includes a number of innovative tools including data assimilation and uncertainty quantification, new models of near-Earth electromagnetic wave environment, ensemble predictions of solar wind parameters at L1, and data-driven forecast of the geomagnetic Kp index and plasma density. The developed codes may be used in the future for realistic modelling of extreme space weather events. The PAGER consortium is made up of leading academic and industry experts in space weather research, space physics, empirical data modelling, and space environment effects on spacecraft from Europe and the US.
High-resolution imaging of the deep structure of Italy through SKS anisotropy tomography
Authors: Baccheschi Paola , Confal Judith M. , Pondrelli Silvia , Faccenda Manuele , VanderBeek Brandon P. , Huang Zhouchuan
Published: February 2023

Seismic anisotropy is a fundamental key to gain knowledge of the mantle dynamics and structure. The image of seismic anisotropy over the upper mantle can be obtained with several methods, including surface waves and SKS splitting measurements. Taken together, these anisotropic measurements contribute to extensively catch anisotropy at different depths, yielding insights into the structure and dynamics of the crust and upper mantle. Nevertheless, mantle images resulting from surface waves result in poor lateral resolution, while the nearly vertically propagating SKS waves, when interpreted in a ray-based framework, results in little or no depth resolution, not allowing to easily image the distribution of the anisotropy through depth. Though the anisotropic seismic nature of the upper mantle is well established by a wealth of observational research, most of common teleseismic body-wave tomography studies neglect P- and S-wave anisotropy, thus producing artefacts in tomographic models in terms of amplitude and localization of heterogeneities. To overcome this problem different tomographic methods have been implemented to invert SKS splitting observations for anisotropic structures, most of which based on finite-frequency sensitivity kernels that relate elastic model perturbations to splitting observations. In this study we adopted the tomographic method relying on the inversion of the splitting intensity, a measure of the amount of energy on the transverse component of the waveform. Since is linearly related to the elastic perturbations of the medium through the 3-D sensitivity kernels, SI can therefore be easily inverted, providing the basis for a better interpretation of shear wave splitting measurements. In this study, we first compute the splitting intensity (SI) and splitting parameters using teleseismic shear-wave recorded at 824 available permanent and temporary stations in Italy and surrounding regions. Then, the dataset of SI has been used as an input for the tomographic inversion. The results obtained show changes of the anisotropic properties with depth, especially for the strength of anisotropy. A progressive depth-increase in anisotropy intensity has been recovered over Italy, affecting the bulge of the Alps and Apennines chain and the southern Tyrrhenian subduction system. On the contrary, weaker anisotropy characterizes the transition zone from the Apenninic to Alps domain beneath the Po plain and the Adriatic domain. The anisotropic tomography models obtained in this study allowed us to recover for the first time a new 3D-imaging of seismic anisotropy of Italy down to the deeper layers, allowing to better understand the dynamic of asthenospheric mantle flow and its relation with subducting plate, as well as the rheology of the continental lithosphere.
Assessing the impact of Veterinary Antibiotic species on Treatment Wetland Nutrient Removal at the Mesocosm Scale
Authors: Russell Matthew
Published: February 2023

Natural and constructed wetlands are now frequently used across the United States for mitigating nitrate losses to both surface and groundwater. Though the use of wetlands as a treatment approach for nitrate in runoff is well known, other active contaminants regularly co-occur with nitrate, potentially affecting the efficacy of nitrate-N removal. For example, veterinary pharmaceuticals have been observed in runoff originating from fields that receive livestock facility animal waste. In 2022, two mesocosm experiments were conducted to evaluate the combined effects of 4 common-use veterinary antibiotics (VAs) (chlortetracycline, sulfamethazine, lincomycin, monensin) on nitrate-N reduction efficiency. We hypothesized veterinary antibiotics would significantly impact nitrate-N removal through changes in denitrification processes within wetland ecosystems. To test this hypothesis, we simulated two pulse-flow storm events (2.5mg N03-N/L, 7.5 mg N03-N/L) and quantified the combined effects of trace-level antibiotics (1.0 mg/L) on the nitrogen cycle in fully saturated treatment wetlands. Results from previous experiments we conducted suggest nitrate reduction rates in treatments receiving antibiotics (CA= -1.04, FTWA= -1.31) remove nitrate more efficiently than those without (C= -0.01, FTW= -0.52). Plant uptake of VAs was also assessed, with results indicating that accumulation of VA compounds in wetland plants occurs and is primarily limited to the below ground biomass (Above ground= 0.59mg per plant, Below ground=206.66mg per plant) and the antibiotic species. Findings from these experiments will provide new insight into whether antibiotic residues in wetland environments affect proposed mitigation strategies for controlling nitrogen losses from fertilized crops and managing nitrate contamination of ground and surface water.
Return levels of extreme European windstorms, their dependency on the NAO, and potential future risks
Authors: Priestley Matthew , Stephenson David , Scaife Adam
Published: February 2023

European windstorms experience considerable interannual variability, which makes the quantification of extreme return periods challenging. Estimating 200-year return levels is also complicated by having only ~60 years of comprehensive observational data. Such estimations of return periods are often performed using ‘catastrophe models’, which use complex calibration and tuning processes.  We have developed a reliable statistical model to estimate extreme windstorm gust speed return levels from only a multi-year sample of windstorm footprints without the need for the complexities associated with catastrophe models. We have also been able to include variations of the NAO in our estimates, allowing for the generation of NAO-dependent return levels. Positive phases of the NAO result in larger return levels across the northwest of Europe. Additionally, the NAO is shown to be especially important for modulating low return period gusts, with the most extreme gusts occurring due to further stochastic processes. Using plausible future states of the NAO we also show that return levels have the potential to increase significantly in the next 100 years to rise well above historical uncertainty levels.
From solar radiation estimation to solar energy potential in the High Arctic
Authors: Garreau Arthur , Nord Torodd , Sjöblom Anna , Shestov Aleksey
Published: February 2023

The High Arctic is a remote region with a harsh climate where communities mainly rely on fossil energy sources. In Longyearbyen, located in the archipelago of Svalbard at 78°N, solar energy is considered as one of the future energy sources. The available solar radiation must therefore be estimated to have solar energy as part of the energy mix. To achieve this goal, the University Centre in Svalbard has maintained a weather station that has recorded ten years of solar radiation data with a Kipp and Zonen CNR1 net radiometer. Additional pyranometers have been installed at other locations, at different altitudes, and with different configurations to establish a more complete atlas of the solar irradiance around Longyearbyen.
The solar irradiance in the High Arctic has different characteristics than that usually encountered at mid-latitudes. There are 24 hours of sunlight during summer and polar nights during winter. When the sun is present, its position and path in the sky differ from further south. In addition, the air mass, atmospheric aerosols, and albedo have an impact on radiation that is peculiar to the Arctic. All those specificities have yet to be completely understood for the Arctic, and hence some uncertainties remain about solar radiation.
A better understanding of the solar radiation received in Longyearbyen will help implement the future solar energy solution for the Arctic. The aim is to accurately estimate solar radiation at high latitudes, capture variability and predictability, and understand which solar cell configuration is optimal. In particular, differences between horizontal and plane-of-array irradiance have been investigated because of the very low elevation angle of the sun. The solar radiation distributions over different time scales have further been assessed using observations. Moreover, the impact of external factors on solar radiation, such as albedo, has been considered. In the future, the collected data will be used to assess Svalbard's solar PV potential.
SONICS: A new Peruvian hydrological dataset of simulated daily streamflow for flood monitoring and forecasting
Authors: Llauca Harold , Leon Karen , Lavado Waldo , Felipe Oscar
Published: February 2023

Increasing hydrological risks and water use puts pressure on water resources and highlights the importance of a systematic hydrological analysis and modeling at national scale in gauged and ungauged catchments. This paper aims to develop a national hydrological model using physiographic and climatic characteristics to compute dissimilarity indices to pair donor and receptor sub-basins for the entire Peru. Therefore, we use the gridded hydrometeorological PISCO dataset (0.1º x 0.1º) to drive a conceptual rainfall-runoff (ARNO/VIC) model, which serves as an input for a river-routing (RAPID) model in thousands of river reaches. We identify 122 similarity-based hydrological zones across the country to run the hybrid model (ARNO/VIC+RAPID) with previously calibrated parameters. National daily streamflow simulations show good performance (KGE ≥ 0.75, NSEsqrt ≥ 0.65, MARE ≤ 2, and -25% ≤ PBIAS ≤ 25%) for catchments located at the Pacific coast and the Andes-Amazon transition. Finally, a new hydrological dataset of daily flow series for entire Peru is presented, including a temporal coverage from 1 January 1981 to 31 March 2020. This new product represents an important contribution for water resource modeling including future risk scenario simulations in often poorly gauged catchments in Peru.Keywords: Peru; PISCO; hydrological regionalization; large-scale modeling; national streamflow simulation. 
Using the radiocarbon bomb spike to constrain the age of soil organic carbon delivered to Lake Constance sediments.
Authors: Mittelbach Benedict V.A. , White Margot E. , Rhyner Timo , Wartenweiler Stephan , Haghipour Negar , Wessels Martin , Blattmann Thomas M. , Dubois Nathalie , Eglinton Timothy I.
Published: February 2023

The residence time of carbon in terrestrial ecosystems, such as soils and freshwater, sets the pace of the terrestrial carbon cycle. Understanding export pathways and turnover times of soil organic carbon (OCSoil) is crucial to assess responses to climate and land use changes. Our study aims to quantify the average turnover time of OCSoil in the catchment of perialpine Lake Constance. Lake sedimentary sequences integrate organic carbon from their catchment and aquatic primary productivity. They act as both burial sites of organic carbon (OC) and time series archives of catchment processes. Thus, they can bridge the gap between plot scale observations, e.g., on soil carbon turnover, and observations made at the outlet of major river systems.Sedimentary organic carbon sources include aquatic primary productivity, OCSoil, and rock-derived (petrogenic) OC. Stable carbon isotopes (δ13C) can be used to identify the relative contribution of these pools. The 5700-year half-life of radiocarbon (14C) coupled with the atmospheric nuclear bomb spike in the early 1960s can be used to infer the age and turnover rate of the OC pools on millennial to annual timescales. Bulk OC isotope analysis of a varved sediment core spanning the past ca. 110 years at quasi-annual resolution was used to constrain the age of soil carbon delivered to Lake Constance. We combined the geochemical data with a Markov-Chain-Monte-Carlo-based approach to identify the most probable age structure of aquatic and soil-derived OC components and to quantify their respective contributions in addition to petrogenic OC.Radiocarbon analysis of sedimentary bulk OC reveals a well-defined but muted bomb spike in the early 1960s. However, bulk Δ14COC values remain below 0‰, implying a predominance of aged OC. Based on the δ13C-based three-component linear mixing model, we found these values to be the result of an OC mixture containing approx. 40% pre-aged soil carbon and up to 20% fossil petrogenic carbon.  Accounting for these inputs, we estimated that soil-derived OC delivered to Lake Constance is centennial in age, implying interim storage prior or subsequent to erosion from the landscape.
Policies to Achieve Sustainability in the Colorado River Basin under Climate Change Conditions and Growing Demand: A Hydro-economic Analysis
Authors: Crespo Daniel , Nemati Mehdi , Dinar Ariel , Frankel Zachary , Halberg Nick
Published: February 2023

Colorado River Basin faces a supply crisis that makes the water system vulnerable to failure, economic losses, conflicts between regions and water users, and ecosystem degradation. The crisis results from water management that allows excessive water withdrawals, legal restrictions established on historical facts, and decreased water availability due to climate change. The agricultural sector, urban centers, hydropower production, and aquatic ecosystems compete for the exhaust water resources in the basin. Despite the reduction in per capita urban water usage and reduction of irrigated land, projections of population and economic growth and increasing crop evapotranspiration indicate an expansion of water demand. The shrinking water availability and growing demand for water will exacerbate existing problems, hampering water management. This article evaluates several alternatives to water management to identify the sectoral and spatial trade-offs of water use by the agricultural sector, urban centers, hydropower production, and aquatic ecosystems. A hydro-economic model is developed to assess current and alternative water allocation’s economic impact on drought, climate change, and growing population. The model examines coalition arrangements among some or all basin states, Tribal Nations and Mexico and the implementation of institutional reforms such as water markets, proportional sharing, and mechanisms that promote water savings. The development of existing but unused Tribal Nation rights is analyzed to evaluate its impact and to determine the potential for new agreements. Simulation shows that shrinking water allocation promotes efficiency improvements and strengthens the sustainability of the water system. However, droughts and climate change erode the benefits of water use and environmental conditions. Reductions in hydropower generation results in economic losses and higher greenhouse gas emissions. Urban centers endure heavy welfare reductions due to water use restrictions, but purchasing water from irrigation districts alleviates the burden and enhances the social surplus. Water markets and cooperation mitigate benefit losses but increase the pressure on ecosystems. Water exchange and side payments (for improved water savings) between states and irrigation districts indicate potential improvements in water use efficiency. Crops with high economic value that are irrigated with advanced technologies are maintained in production. Instead, field crop producers suffer from water shortages. Improvements in irrigation technology reduce the risk of exposure to water scarcity but curtail water returns than sustain ecosystems and downstream activities. Maintaining tribal Nations' rights and establishing environmental flows rectify the inefficient use of water by other users.
The location of the spectral break in compressible fluctuations in the solar wind.
Authors: Roberts Owen , Nakamura Rumi , Narita Yasuhito , Voros Zoltan
Published: February 2023

We use density deduced from spacecraft potential to study the power spectral density (PSD) of fluctuations in the solar wind. Typically plasma measurements do not have high enough time resolutions to resolve ion kinetic scales. However, calibrated spacecraft potential allows much higher time resolutions to resolve the spectral break between ion inertial and kinetic ranges. Fast Survey mode data from Magnetospheric MultiScale data are used when the spacecraft were in the pristine solar wind. We find that the density spectra' morphology differs from the magnetic field fluctuations, with a flattening often occurring between inertial and kinetic ranges. We find that the spectral break of the trace magnetic field fluctuations occurs near the expected frequency for cyclotron resonance or magnetic reconnection. Meanwhile, the spectral break at the start of the ion kinetic range for density fluctuations is often at a higher frequency when compared to the magnetic field. We discuss possible interpretations for these observations. Two plausible scenarios are presented; 1. the compressive fluctuations consist of a slow wave cascade at large scales before kinetic Alfven waves become dominant at smaller scales 2. charge separation begins to occur at these scales, and the Hall electric field starts to play a role. 
Multi-annual prediction of drought and heat stress to support decision making in the wheat sector
Authors: Solaraju-Murali Balakrishnan , Gonzalez-Reviriego Nube , Caron Louis-Philippe , Ceglar Andrej , Toreti Andrea , Zampieri Matteo , Bretonnière Pierre-Antoine , Samsó Cabré Margarita , Doblas-Reyes Francisco J.
Published: February 2023

Unfavourable and extreme climate events such as drought and heat stress heavily impact the agriculture sector and food security globally, and the impact of these climate hazards is expected to increase over the upcoming years due to anthropogenic climate change. Decadal climate predictions have been made available to stakeholders in the agriculture sector as a potential source of near-term climate information that provides forecasts for the following 10 years, thus providing an important source of information for increasing preparedness and for adaptation. In this study, the ability of such forecasts to predict climate extremes on a multi-annual timescale is explored. In particular, the skill and reliability of decadal probability forecasts to estimate user-relevant agro-climatic indices, such as the Standardized Precipitation Evapotranspiration Index (SPEI), for the months preceding the wheat harvest on a global spatial scale, will be presented. Following this, the added value of such climate information with respect to using past observed climatology or standard (uninitialized) climate projections will be shown. The applicability of decadal forecasts to enhance the adaptation and mitigation activities in the agricultural sector will be illustrated.
The Weddell Gyre: what drives a long-term increase in surface nutrients?
Authors: Reeve Krissy Anne , Hoppema Mario , Kanzow Torsten , Boebel Olaf , Geibert Walter , Strass Volker
Published: February 2023

The Weddell Gyre plays a role in connecting the deep ocean to the surface through upwelling, and also in feeding heat towards the Antarctic ice shelves, regulating the density of water masses that feed the deepest limb of the global overturning circulation. Using Argo floats freely drifting throughout the Weddell Gyre, we describe its horizontal circulation as an elongated double-gyre system, with stronger transports in the east than in west, impacting water property distribution. The eastern sub-gyre region is also associated with stronger upwelling rates than in the west, as shown by radionuclide concentrations. To gain insight to long-term changes in the Weddell Gyre, nutrient concentrations can also be investigated as oceanic tracers. We determine long-term trends in surface silicates, a necessary nutrient for silicifying phytoplankton, from ship-based measurements since 1996, and find that the strongest increase is found in the central western sub-gyre region. In association with the eastern sub-gyre, long-term trends along the Prime Meridian are strongest (albeit weaker than in the central western sub-gyre) in the westward flowing southern limb of the gyre, downstream of Maud Rise. We hypothesize that there are different dynamical drivers, such as wind-driven upwelling (west) and turbulent mixing (east), which cause the positive silicate trends in the east versus the west, which are investigated accordingly.