bluuebunny/crossref_metadata_2025 huggingface dataset:
Subaerial lava as a source of coastal hydrothermal iron
Authors: González Santana David , González Aridane G. , Arnone Veronica , González-Dávila Melchor , Santana-Casiano J. Magdalena
Published: February 2023

The interaction between lava and seawater has received significant interest, since multiple reactions can take place which act as sources or sinks of elements, consequently changing the chemical properties of the surrounding seawater. However, most of these studies are based on underwater hydrothermal vent sites. On the 19th of September 2021, 6 km away from the coast, the Tajogaite volcano in La Palma, Canary Islands started its eruptive phase.
Lava flows reached the shoreline during three events on September 28th, November 10th, and November 22nd, strongly affecting the seawater properties as they interacted with the seawater. The evolution of surface and water column physicochemical properties (temperature, salinity, carbonate system variables, dissolved oxygen), iron concentrations (soluble (sFe), dissolved (dFe) and total dissolvable (TdFe)) concentrations, and iron ligands were characterized during 13 visits to the frontal zone of the newly formed deltas. A large volume of hot (50°C measured on November 12th) and high salinity seawater promoted pH values in the frontal zone of 7.0 with important decreases in alkalinity and total dissolved inorganic carbon. These waters were also characterised by high iron concentrations reaching 18 nM, 117 nM, and 2024 nM for sFe, dFe, and TdFe, respectively. The affected waters travelled in the top meter of the water column over 1 km away from the coast, naturally fertilising the surrounding photic layer.
Do the TCRE and ZEC metrics work under net negative CO2 emissions?
Authors: Koven Charles , Sanderson Benjamin , Swann Abigail
Published: February 2023

Two key metrics of the coupled carbon-climate system are used to inform the remaining carbon budget for climate stabilization: the transient climate response to cumulative CO2 emissions (TCRE) and the zero emissions commitment (ZEC), which govern the global temperature response to positive and zero emissions, respectively. We ask whether and how these two metrics describe global temperatures under net negative CO2 emissions, using an idealized scenario defined by a gradual and symmetric reversal from positive to negative emissions. Using a full Earth system model and an ensemble of simple climate model simulations, we show that the two metrics do capture the global temperature dynamics even under large amounts of negative emissions, with ZEC predicting the deviation from symmetric TCRE proportionality under negative emissions. Further, we show that because ZEC begins to influence global temperatures even before reaching net zero, it can be better thought of as a measure of the deviation from the path-independence of the TCRE relationship than as a measure of the committed warming after reaching net zero.
Seasonal and Interannual Variability in Dust Flux to High-Elevation Ecosystems in the Southwestern United States
Authors: Munroe Jeffrey
Published: February 2023

The transport of mineral dust from arid lowlands to higher elevations has profound consequences for the geoecology of mountain ecosystems.  With expanding human populations and widespread disturbance due to land use, dust deposition rates and compositions are changing, presenting unique challenges for human and ecosystem health.  The American Southwest, a region that has experienced a massive increase in dust deposition rates in the past century, is no exception to this trend.  Understanding the flux and composition of dust can help identify where dust is coming from, and can inform management strategies for dust emitting landscapes.  As part of the DUST^2 Critical Zone Thematic Cluster, this project utilized a network of 18 passive dust traps in the southwestern US, 15 of which were deployed on high mountains summits and ridgelines.  The dust traps were emptied biannually between 2020 and 2022 to reveal spatial and temporal differences in dust compositions and depositional fluxes.  Results demonstrate that dust flux is higher in the summer compared to winter; at the 13 collectors with the most complete data, summer fluxes averaged 47.9 mg/m2/day whereas winter fluxes averaged 24.2 mg/m2/day.  Interannual variability is notable: for instance, some collectors received 2x as much dust in summer 2022 vs. 2021, whereas for others the pattern was reversed.  In contrast, all collectors received more dust during winter 2021-22 than in 2020-21.  Superimposed on these temporal differences is a spatial disparity in accumulation rates, with the highest values at the urban sampler in Salt Lake City and at sites immediately downwind.  In contrast, lower fluxes are common at high elevation sites in Nevada, particularly during the winter.  Overall, measured dust fluxes span a wide range from 5.3 to 255 mg/m2/day.   The grain size distribution, color, mineralogy, and geochemistry of dust also vary notably between sites, supporting the interpretation that much of the dust is sourced from the immediately surrounding lowlands.
Moisture sources projections under climate change for Atmospheric Rivers landfalling the Iberian Peninsula
Authors: Fernández-Alvarez José C. , Perez-Alarcon Albenis , Eiras-Barca Jorge , Ramos Alexandre , Alvarez-Socorro Gleisis , Rahimi Stefan , Nieto Raquel , Gimeno Luis
Published: February 2023

A combination of Flexpart-WRF simulations forced with ERA5 and the CESM2 model incorporated in the CMIP6 project to infer a series of changes over the present century in the behavior of the landfalling ARs arriving at the Iberian Peninsula was used. Potential changes in the strength and position of their main moisture sources are also studied first in the literature. In general terms, a gradual strengthening in the intensity of these events is expected, observable from an increase in the amount of moisture transported, while no significant changes in the net number of events are observed. A northward shift in the position of the centroids has also been detected. In relation to the moisture sources, an increase in the contribution of these sources to the moisture content is expected, compatible with Clausius-Clapeyron amplification.
Linking Precipitation Size and Velocity Distribution with Snowpack Height Changes
Authors: Durán Luis , González-Cervera Álvaro
Published: February 2023

The snowpack is a fundamental element of the cryosphere and understanding its dynamics is crucial for regions where runoff  is the main source of freshwater. Snowpack variations in very short periods of time can have important security and logistical consequences. On the other hand, snowpack height measurements are complex due to its high spatial variability. The thermodynamic and physical processes that the snowpack undergoes are complex and are dominated by meteorological forcings which are also complex, specially in mountain regions. The most important forcing in terms of snowpack height variation is precipitation. It is well known how precipitation in the form of rain decreases the height of the snowpack almost immediately, while precipitation in the form of snow,  increases its height. The problem is that precipitation occurs with a variety of populations of phases, so this mixed precipitation makes the conversion between precipitation and snow height increase not straightforward.  Disdrometers are instruments capable of determining the size and speed at which precipitation falls very precisely. The population of different sizes and terminal velocities is known as the spectrogram. This map of velocities and sizes makes it possible to estimate the phase since their terminal fall velocities of rain and snow are very different. These instruments are very useful to determine the intensity of mixed precipitation and are widely spreaded in airports, highways and mountain areas. In this work we analyse the possibility of developing a relatively simple algorithm that from the size and velocity distributions detected by a disdrometer we could predict the variation of the snowpack in the next few hours. Several techniques have been tested in this work, some of them simple correlations. But the method that really outstanded was the one based on a reduction of the dimensions of the spectrograms applying a principal component analysis which is then used to search analogue situations. Although the available data is still very small, the results encourage to refine this technique when more data will be available in the next winters.
Characterizing and simulating with blunt extension of discrete cascades rainfall anisotropy in a Universal Multifractals framework
Authors: Gires Auguste , Tchiguirinskaia Ioulia , Schertzer Daniel
Published: February 2023

Rainfall fields exhibit extreme variability over wide range of space-time scales which make them complex to characterize, model and even measure. Furthermore, rainfall, as most geophysical fields, is strongly anisotropic. Fortunately, scaling anisotropy has been developed for a few decades to generalise scaling in an anisotropic framework, e.g., in the simplest case iso-surfaces become self-affines ellipsoids instead of self-similar spheres. This is particularly straightforward for continuous in scale cascades. For them, as well as for discrete in scale cascades, Universal Multifractals (UM) have been widely used to analyse and simulate such geophysical fields with the help of a very limited number of physically meaningful parameters. Recently blunt cascades have been introduced. They enable to remain in the simple framework of discrete cascades while partly overcoming their well known strong limitations such as non-stationnarity. It basically consists in geometrically interpolating over moving windows the multiplicative increments at each cascade steps.Here we suggest to incorporate observed features in blunt 2D and 3D (space-time) blunt discrete cascade simulations. The data analysis corresponds to a 1D analysis along various directions ,considering each lof them as a different “sample” of the process. Analysing how the UM parameters change with the angle of the chosen direction enables to unveil underlying rainfall anisotropy features. Impacts, and notably potential biases, of these features on standard spatial analysis in 2D are also explored and discussed. For this purpose high resolution space-time rainfall data collected with help of a dual polarisation X-band radar operated by HM&Co-ENPC is used .To simulate anisotropy features with the help of blunt extension of discrete UM cascades, we tentatively suggest to use moving window shaped as ellipses instead of squares. Tuning the eccentricity and orientation of the ellipses enables to introduce various levels of anisotropy within the simulated fields. First, multifractal expected behaviour is theoretically established and then it is numerically confirmed with the help of ensembles of stochastic simulations and the previously developed analysis approach.Authors acknowledge the RW-Turb project (supported by the French National Research Agency - ANR-19-CE05-0022), for partial financial support.
Sea salt aerosol and ice nucleating particles (INP) in the Central Arctic during winter/spring – a discussion of a source from blowing snow above sea ice
Authors: Frey Markus M. , Kirchgäßner Amélie , van den Heuvel Floor , Lachlan-Cope Thomas , Stratmann Frank , Wex Heike , Macfarlane Amy R. , Mirrielees Jessica , Pratt Kerri , Beck Ivo , Schmale Julia , Nishimura Kouichi , Brooks Ian
Published: February 2023

Arctic clouds are poorly represented in climate models partly due to a lack of understanding of their source and nucleating capability of natural aerosol in the high Arctic. Recent field campaigns provided evidence of a source of sea salt aerosol (SSA) from blowing snow above sea ice, which can account for SSA winter/spring maxima observed in the polar regions. SSA emissions from sea ice sources can potentially influence regional climate via the indirect radiative effect, but contributions to cloud-forming particles, in particular, ice-nucleating particles (INP), are unknown. Here we report the first online spring-time observations of INPs in the Central Arctic. INP concentrations were on the order of a few tens [particle m-3] activating between -38 and -15°C and were often associated with high wind speeds. Initial offline droplet assay analysis of snow on sea ice indicates the presence of potential INPs in winter/spring activating at -29 to -25°C. This is evidence that snow on sea ice represents a viable reservoir of INPs, which can be physically released via the blowing snow mechanism to the air above. We discuss sea ice sources of coarse SSA and INPs and their role in the lower atmosphere with a focus on blowing snow. To do this, we consider the comprehensive set of MOSAiC observations, including aerosol size and composition, airborne snow particles, and chemical and physical properties of both aerosol and snow on sea ice.
Characterizing the impact of spatial scales on near-surface wind speed and wind power generation in a mountainous environment
Authors: Helbig Nora , Hammer Florian , Barber Sarah
Published: February 2023

Near-surface wind fields are altered over mountainous topography, giving rise to complex wind flow patterns due to sheltering, acceleration, channelling, deflections, blocking or recirculation. However, the impact of the resulting spatio-temporal wind fields on wind energy potential remains largely unknown. While wind modelling approaches can describe highly resolved spatio-temporal wind fields in mountainous terrain rather well, wind fields cannot be generated in a reasonable amount of computational time. Models are therefore strongly limited in space and time for many applications. In mountainous regions, wind farm planning is thus much more challenging than in flat regions.To investigate the variability of wind fields and its impact on wind energy production in mountainous terrain, we applied a computationally efficient statistical downscaling model approach to a small region in the Swiss Alps. This allowed us to analyze the impact of horizontal resolutions on spatial wind speeds and energy yield in a mountainous area. We applied the statistical approach of Helbig et al., 2017 to downscale coarse wind speed values to the fine scale based on local terrain parameters. This approach introduces two dominant local wind-topography interactions: sheltering and speed-up on coarse wind speed. Then, based on the resulting spatio-temporal near-surface wind fields and a common theoretical power curve, we calculated long-term wind energy yield. Through a sensitivity analysis, we assessed the impact of varying horizontal spatial resolutions in the mountainous environment on overall and local wind energy yield. Specifically, we addressed the impact when decreasing horizontal resolutions from grid cell sizes of 100 m down to 5 m. Resulting spatial variations will be discussed as functions of local terrain parameters, as well as wind speeds.Helbig, N., Mott, R., van Herwijnen, A., Winstral, A. and Jonas, T. (2017): Parameterizing surface wind speed over complex topography. J. Geophys. Res., 122, 651–667.
Reconciling the moisture sources of the extreme flood event in July 2021 over western Europe
Authors: Benedict Imme , Weijenborg Chris , Vermeulen Thomas , Keune Jessica , Sodemann Harald , van der Ent Ruud , Kalverla Peter
Published: February 2023

From the 12th to the 15th of July 2021, Western Europe was confronted with an abnormal amount of precipitation leading to extreme floods and enormous damage in western Germany, Belgium, Luxembourg and the south of The Netherlands. Locally, almost thrice as much as the monthly precipitation amount was observed, culminating in 175 mm of rain in just two days. Dynamically, a stationary upper-level cut-off low was the driver of moisture transport to the region resulting in the extreme precipitation over a large area. A follow-up step to unravel the hydrometeorology of the event, is to understand the evaporative regions (moisture sources) that contributed to the event. In literature, these different source region contributions were presented, either indicating the importance of transpiration from vegetation over North America and Europe, or highlighting the role of the Baltic sea, which experienced a heatwave and high evaporation rates at the same time.Here, we reconcile the moisture sources of the flood event in July 2021 and its uncertainties by comparing the results from three different moisture tracking models (WaterSip, HAMSTER & WAM-2layers) forced with ERA5. By further addressing model-internal sensitivities, we (can) provide a thorough estimate of the uncertainty of contributions from different regions to precipitation during the extreme event, and we ascertain the mechanisms that played a role. Our first results confirm that central Europe is the largest contributor of moisture for precipitation during the event (45 – 90%), whereas the Baltic contributed very little (0 – 5%), thereby contrasting results from recent single-model studies. However, substantial differences were found between the moisture tracking models indicating the need to better understand where those difference arise from and employ multi-model moisture tracking intercomparison studies in the future. 
Reduced stratospheric variability following sudden stratospheric warming events
Authors: Rupp Philip , Spaeth Jonas , Garny Hella , Birner Thomas
Published: February 2023

Sudden stratospheric warming (SSW) events can form a window of forecast opportunity for polar vortex predictions on subseasonal-to-seasonal time scales. Analysing numerical ensemble simulations, we show that negative wind anomalies in the polar stratosphere following SSWs lead to a reduction in upward planetary wave propagation and hence a reduction in the dynamical variability of the polar vortex. Ensembles that predict an SSW show reduced ensemble spread in terms of polar vortex strength for several weeks to follow, as well as a corresponding reduction in forecast errors. The associated increase in predictability is particularly pronounced for strong SSWs and even occurs if not all ensemble members predict a major SSW. The decrease in upward wave fluxes and polar vortex variability following the event then manifests in a delay of the final warming during years that experience an SSW and potentially has further implications for the tropospheric or mesospheric circulation.
ISAMO (Iron Salt Atmospheric Methane Oxidation)
Authors: Johnson Matthew S. , van Herpen Maarten M. J. W. , v/d Kraats Berend , Li Qinyi , Saiz-Lopez Alfonso , Liisberg Jesper B. , Pennacchio Luisa , Röckmann Thomas
Published: February 2023

Methane is a well-mixed greenhouse gas responsible for >1/3 of global warming since pre-industrial times whose atmospheric burden continues to increase with a new record set in 2022. Active chlorine in the atmosphere is poorly constrained and so is its role in the oxidation of methane. This uncertainty propagates into methane source budgets through isotope-constrained top-down models, in which the observed abundance of 13C in tropospheric methane (commonly expressed as δ13C-CH4) is used to constrain the sources of methane using their characteristic δ13C-CH4 values. These models need to account for the change in the observed δ13C-CH4 by the Cl and OH sinks, which shift the observed isotope towards higher δ13C-CH4 values of fossil fuel sources, and away from 13C depleted biological sources. The ISAMO project focuses on the hypothesis that Cl atoms are produced naturally by the action of sunlight on particles containing iron and chloride and these chlorine atoms oxidize atmospheric methane. To study this, we use the sensitive and selective indirect quantification of the concentration of atomic Cl through the strong carbon kinetic isotope effect (KIE) in the CH4 + Cl reaction, which leaves the remaining CH4 enriched in 13C, and producing extremely 13C-depleted CO. We will present field and laboratory observations and global modelling, including CO isotope measurement from flasks samples across the North Atlantic. We show how this mechanism affects 13C depletion in atmospheric CO and how the corresponding 13C enrichment in CH4 affects global methane emission estimates.
An isotope-enabled modeling approach to track snowmelt and groundwater contribution to runoff and root water uptake in a snow dominated mountainous catchment
Authors: Sprenger Matthias , Kuppel Syvain , Carroll Rosemary , Ulrich Craig , Williams Kenneth
Published: February 2023

The snow dominated headwaters of the Colorado River are crucial for the water supply of the south-western US. The current water crisis in the Colorado basin makes understanding runoff processes in mountainous regions more necessary than ever. We present how our observations of stable isotopes of water (2H and 18O) in the precipitation, stream-, soil-, xylem-, and groundwater at the East River in the upper Colorado River, combined with multiple hydrometric datasets since 2014 (multi-location stream gauging, groundwater levels, soil moisture snow water equivalent, and eddy-covariance fluxes), can be used to rigourously contrain and evaluate an ecohydrological modelling tool to then identify the time and location of snowmelt and groundwater subsidies to runoff and plant water use. To this end, we deployed a new version of the spatially-distributed, process-based model EcH2O-iso, with a multi-objective model-data fusion procedure. The simulations notably underline the dominant role of snowmelt as a main driver of runoff generation, through its direct contribution to runoff peak during the late spring snowmelt, and to the groundwater recharge that eventually feeds the significant baseflow contribution in this catchment. Our analysis further explores the use of water ages and numerical tracers to better disentangle these cross-seasons carry-over of water between critical zone compartments.
Linking production of carbonyl sulphide to the composition of the marine dissolved organic matter pool
Authors: Simon Heike , von Hobe Marc , Dittmar Thorsten , Lennartz Sinikka Tina
Published: February 2023

Sulfur containing trace gases impact Earth’s climate, and the ocean is a major natural source for the most abundant sulfur gas in the atmosphere, carbonyl sulfide (COS). Understanding and quantifying COS oceanic emissions is relevant for closing the gap in the atmospheric COS budget, which currently impedes conclusions about trends in stratospheric aerosol formation and gross primary production on a global level. The main production process of COS in surface seawater, photochemical production, remains one of the largest uncertainties in quantifying marine COS emissions. Precursors of COS are dissolved organic molecules, which form an enormously diverse mixture. How the composition of this diverse pool influences COS production has not yet been fully understood.Here we present continuously measured COS concentrations in seawater and the marine boundary layer to quantify the relationship between photochemical production of COS in various marine regions: Along a North-South Atlantic transect from Bremerhaven to Cape Town and at two stations in the North Sea, one located in the open sea area close to Heligoland, one in the Wadden Sea area close to Spiekeroog Island. Samples of dissolved organic matter (DOM) were taken twice daily for subsequent analysis of the molecular composition and optical properties of the large precursor pool for COS photo- and dark production. Concentrations of COS in surface seawater showed distinct diurnal cycles with considerable day-to-day variations. The marine DOM pool differed with respect to sulfur containing molecules mainly between locations, and less along diurnal cycles. Our results will help to improve mechanistic models of marine COS cycling, especially with regard to the currently existing uncertainties in the global emission estimate of COS.
Unraveling fire-permafrost interactions in Northeastern Siberian tundra using InSAR and machine learning
Authors: Wangchuk Sonam , Schaefer Kevin , Michaelides Roger , Vonk Jorien , Veraverbeke Sander
Published: February 2023

Permafrost soils in boreal forests and tundra store more than two atmospheres worth of carbon, yet the vigorous permafrost-carbon-climate feedback loop remains poorly understood. In addition to ongoing strong warming, fires can further accelerate permafrost degradation and trigger the release of ancient carbon into the atmosphere. Despite the urgency after the recent Arctic fire seasons of 2019, 2020 and 2021, fire-permafrost interactions are currently not included in Earth system models from the sixth assessment of the Intergovernmental Panel on Climate Change (IPCC). This is because large-scale observations of fire-induced permafrost degradation are lacking. Therefore, we studied fire-induced permafrost degradation using the Interferometric Synthetic Aperture Radar (InSAR) technique and time series of Sentinel-1 (S-1) imagery. In this pilot study, we tested our approach on fires from 2019 and 2020 in the Chokurdakh area, Northeastern Siberia. We processed time series S-1 SAR data from a snow-free season (June-October) where S-1 SAR image selection was automated by using the Moderate Resolution Imaging Spectroradiometer snow cover products. To understand the drivers of InSAR-derived subsidence, we applied the XGBoost regression algorithm using subsidence as a response variable and ten other environmental variables as predictor variables. First, we found that the time series InSAR technique is suitable for deriving subsidence over fire-affected permafrost terrain. Second, the fire-affected permafrost terrain exhibited four to five times greater subsidence compared to the surrounding unburned area. Third, the XGBoost regression model revealed land surface temperature (LST) and albedo (derived from Landsat data) as the primary predictor variables  of surface subsidence, accounting for more than 50% of the predictive power. The permafrost degradation in many tundra areas is likely dominated by fire-induced changes in the surface energy balance.  From this pilot study, we conclude that our approach has the potential to study fire-permafrost interaction and environmental drivers of surface subsidence at the northern circumpolar scale. Models can also use our data to parameterize subsidence and thermokarst processes associated with permafrost degradation due to fire.
Simulation of ground motions with high frequency components obtained from Fourier neural operators
Authors: Aquib Tariq Anwar , Mai Paul Martin
Published: February 2023

Seismic hazards analysis relies on accurate knowledge of ground motions arising from potential earthquakes to assess the risk of damage to buildings and infrastructure. It is necessary to perform ground motion simulations because recorded strong-motion data from specific combinations of earthquake magnitudes, epicentral distances, and site conditions are still limited. Physics-based simulations provide reliable ground motion estimates, but their application in practice is limited to frequency ranges f < 1Hz, largely due to limited computational resources and lack of information regarding earthquake sources and medium. While hybrid ground-motion computations combining deterministic low frequency components with stochastic high frequency components are often used,  their stochastic high frequency components fail to correctly account for source and path effects and lead to inconsistent building responses.The large database of ground motion records from Japan lends itself to develop machine learning approaches to estimate high frequency ground motions. Applying state-of-the-art machine learning techniques, like Fourier neural operators (FNOs) and Generative Adversarial Networks (GANs), we estimate seismograms at higher frequencies from their low frequency counterparts. In our approach, the time and frequency properties of ground motions are estimated using two different FNO models. In the time domain, a relationship is established between normalised low pass filtered and broadband waveforms. Frequency domain analysis involves the learning of high frequency spectrum from low frequency spectrum. Finally, the time and frequency properties are combined to produce broadband ground motions. Source, site, and path aspects are naturally incorporated into the training process.We use ground motion data collected between 1996 and 2020 at 18 stations in the Ibaraki province of Japan to train our models and validate them on different events (Mw 4 to 7) around Japan. Using goodness of fit measures (GOFs), we show that the resulting ground motions match the recorded observations with good to acceptable GOF values for most of the predictions. To enhance our predictions, we include uncertainty estimation by utilizing a conditioned GAN approach. Lastly, to demonstrate the practicality of the approach, we compute high frequency components for a physics based simulated hypothetical Mw 5.0 earthquake in Japan.
Atmospheric CO2 history of the late Permian and Early Triassic
Authors: Joachimski Michael , Müller Johann , Gallagher Timothy , Matthes Gregor , Chu Daoliang , Mouraviev Fedor , Silantiev Vladimir , Sun Yadong , Tong Jinnan
Published: February 2023

The end-Permian mass extinction, the largest biological crisis in Earth history, is currently understood in the context of Siberian Traps volcanism introducing large quantities of greenhouse gases to the atmosphere. We reconstructed the late Permian to Middle Triassic atmospheric CO2 record by applying the carbonate paleosol pCO2 barometer to soil carbonates from sections in northwest China (Xinjiang Province), north China (Henan and Shanxi Provinces), Russia (South Ural foreland basin), South Africa (Karoo Basin), and the United Kingdom (Dorset). Atmospheric pCO2 shows an approximate 4-fold increase from mean concentrations of 412–919 ppmv in the late Permian (Changhsingian) to maximum levels between 2181 and 2610 ppmv in the Early Triassic (late Griesbachian). Mean CO2 estimates for the later Early Triassic are between 1261–1936 ppmv (Dienerian) and 1063–1757 ppmv (Spathian). Significantly lower concentrations ranging from 343 to 634 ppmv are reconstructed for the latest Early to Middle Triassic (Anisian). In parallel to the reconstructed rise in greenhouse gas levels, low-latitude sea surface temperatures (SST) increased by 7–10 °C, from 25–28 °C to >35 °C (Joachimski et al., 2020). With the decrease in pCO2 in the late Spathian to Anisian, SSTs decreased as well (Sun et al., 2012). Thus, pCO2 as well as SSTs persisted at high levels for almost 5 m.y. In contrast, pCO2 reconstructed using the photosynthetic carbon isotope fractionation suggest much lower atmospheric pCO2 (e.g. Shen et a. 2022), inconsistent with significant warming, while modeling studies suggest up to a 13-fold increase in pCO2 (e.g. Cui et al. 2021). Most important, the 5 m.y. long episode of elevated pCO2 suggests that negative feedback mechanisms such as silicate weathering, the most effective mechanism by which to extract CO2 from the atmosphere and to buffer Earth’s climate, were not effective enough to reduce atmospheric pCO2 to pre-crisis levels. Instead, marine authigenic clay formation (i.e., reverse weathering) may have been an important component of the global carbon cycle keeping atmospheric pCO2 at elevated levels during this critical time interval. References: Cui et al. 2021, PNAS, V. 118, No.37, e201470118; Joachimski et al. 2020, GSA Bull., 132, 427-443; Shen et al. 2022, Nat. Geosc., 15, 839-844; Sun et al. 2012, Science, 338, 366-370.
The World Water Map of water scarcity hotspots
Authors: Wanders Niko , Leijnse Myrthe , Droppers Bram , van Jaarsveld Barry , Hoch Jannis , Götte Jonas , Bierkens Marc
Published: February 2023

The World’s water resources are under severe pressure as a result of unsustainable exploitation and rapidly changing hydroclimatic conditions. In the National Geographic World Water Map project, we combine state of the art hydrological modelling expertise, with storytelling expertise from National Geographic. The World Water Map aims to shed new light on water problems in the world.In this project we identify 17 hotspots of water scarcity based on state-of-the-art large-scale hydrological modelling results. For the so called “hotspots” we analyze which policies, regulations and climatic changes have resulted in the development of these areas under pressure. We do this by using a literature study of over 175 scientific publications, which helps to identify the drivers and pressure as well as their impact and response for each hotspot. This information is then all included in the online Water Map that provides the general public, policy makers and peers in science with this information. The map consists of an interactive web portal where we tell the untold stories of water scarcity, support water scarcity literacy so that people understand the problems surrounding water scarcity, and provide an interactive platform where people can identify the vulnerability of their local neighbourhoods.By combining science and storytelling we can shed light on “hotspots” as well as provide the untold stories in these regions. Together with the local and national policymakers we aim to provide much needed open information on pathways forward and future outlooks for “hotspots” around the world.
Optical properties of the shallow and exposed lightning discharges observed by ASIM
Authors: Li Dongshuai , Neubert Torsten , Chanrion Olivier , Husbjerg Lasse Skaaning , Luque Alejandro , Zhu Yanan , Østgaard Nikolai , Reglero Víctor
Published: February 2023

The Atmosphere-Space Interactions Monitor (ASIM) on the International Space Station (ISS) observes lightning and Transient Luminous Events (TLEs) above the thunderstorm clouds. ASIM includes three photometers that sample at 100 kHz and two cameras that image at 12 frames per second. The photometers measure part of the far ultraviolet (FUV) and middle ultraviolet (MUV) band at 180 – 300 nm, a line of the second positive system of N2 at 337nm (blue) and an atomic oxygen line at 777.4 nm (red). The cameras measure in the blue and red bands of the photometers with a spatial resolution on the ground around 400 m × 400 m. When ASIM is in a nadir-viewing configuration, photometer signals in the blue and red are sometimes associated with coincident UV signals, indicating that the UV photons originated from lightning discharges at cloud altitudes and not from the TLEs at higher altitudes. Here, we analyse the optical properties of these events by combining data from ASIM, the global lightning network GLD360, Lightning Mapping Arrays (LMAs) and NEXRAD radars. Of the 12 cases identified with such data coverage, 5 are Cloud-to-Ground (CG) and 7 are Intra-Cloud (IC) lightnings. The lightning leaders are located nearby the cloud top boundaries or partly exposed outside the cloud. Both the CG and IC lightnings are associated with the exposed lightning leaders. The 5 CG lightnings are identified as the “bolts from the blue”, and the 7 IC lightnings are “cloud-to-air” lightning. The altitudes of the sources vary from 5 km to 7 km for the CG lightnings and from 7 km to 15 km for the IC lightnings. The optical properties for the events, such as their irradiance, rise time and duration in the different optical bands are summarized and discussed. The results provide information that allows to estimate the global occurrence of “bolts from the blue” and “cloud-to-air” lightning.
ORFEUS Data Services, Products and Actions to Coordinate Access to Seismic Waveform Data in the Euro-Mediterranean Region
Authors: Cauzzi Carlo , Bieńkowski Jarek , Crawford Wayne , Custódio Susana , D'Amico Sebastiano , Evangelidis Christos , Haberland Christian , Haslinger Florian , Kiratzi Anastasia , Kolínský Petr , Lanzano Giovanni , Roumelioti Zafeiria , Sigloch Karin , Sleeman Reinoud , Strollo Angelo
Published: February 2023

ORFEUS (Observatories and Research Facilities for European Seismology, orfeus-eu.org) is a non-profit foundation that coordinates and promotes seismology in the Euro-Mediterranean area and beyond, through harmonized collection, archival and distribution of seismic waveform data, metadata, alongside offering services and products managed at national level by more than 60 participating seismological Institutions. ORFEUS is one of the founding members of EPOS Seismology (www.epos-eu.org/tcs/seismology) and a fundamental partner of EC-funded projects. ORFEUS services are largely integrated in the EPOS Data Access Portal (www.ics-c.epos-eu.org). The key goals of ORFEUS (Bylaws, Article I.3: orfeus-eu.org/documents//ORFEUS_Bylaws_September_2022.pdf) are achieved through the development and maintenance of data services targeted to a broad community of seismological data users. ORFEUS comprises: (i) the European Integrated waveform Data Archive (EIDA; orfeus-eu.org/data/eida); (ii) the European Strong-Motion databases (orfeus-eu.org/data/strong); and iii) the recently established group representing the community of European mobile pools, including amphibian instrumentation (orfeus-eu.org/data/mobile). Products and services for computational seismology are also considered for integration in the ORFEUS domain. Currently, ORFEUS services  provide access to the waveforms acquired by ~18,000 stations in the Euro-Mediterranean region, including dense temporary experiments (e.g., AlpArray, AdriaArray), with strong emphasis on open, high-quality data. Access to data and products is ensured through state-of-the-art information and communication technologies, with strong emphasis on federated web services, clear policies and licenses, and acknowledging the crucial role played by data providers. Significant efforts are underway, by ORFEUS participating institutions,  to enhance the existing services to tackle the challenges posed by the Big Data Era, and to actively encourage interoperability and integration of multidisciplinary datasets in seismological and Earth Science workflows.  ORFEUS also implements Community services that include software and travel grants, webinars, workshops and editorial initiatives. ORFEUS data and services are assessed and improved through the technical and scientific feedback of a User Advisory Group, which comprises European Earth scientists with expertise on a broad range of disciplines. 
Mean flow in high-order wave evolution equations at arbitrary depth
Authors: Gomel Alexis , Montessuit Corentin , Armaroli Andrea , Eeltink Debbie , Chabchoub Amin , Kasparian Jérôme , Brunetti Maura
Published: February 2023

Fluid motion under water waves includes an Eulerian return flow in the direction opposite to wave propagation that is of importance for accurately modelling the transport of tracers in the ocean like sediments, plastic pollution, oil, etc. The return flow is related to the mean flow, that is to the derivative in space of the zero-harmonic component of the velocity potential φ0. It turns out that this component is not consistently taken into account in some derivations of the high-order nonlinear Schrödinger equation (HONLS) using the multiscale development at arbitrary depth, which therefore do not correctly reproduce experimental results in the deep-water limit. We show how to formulate a Neumann problem for φ0 that can be solved at fourth order in steepness for arbitrary depth. The derivative of such term is thus included in the HONLS in both cases of propagation in time and in space. We compare the results of the simulations obtained using our model to those obtained with previously published fourth-order models without the mean-flow term, to observations and to accurate simulations performed with the high-order spectral method. While our model is equivalent to alternative formulations in intermediate water, it is more accurate in deep water.  Our model therefore provides the first fourth-order NLS relevant for depths ranging from intermediate to deep water.
Mixing characteristics of the Dutch Wadden Sea: Elucidation based on 11 years of simulation results
Authors: Mitra Aditi , Donatelli Carmine , Duran-Matute Matias , Gräwe Ulf , Gerkema Theo
Published: February 2023

The Dutch Wadden Sea (DWS) is an event-driven aquatic system between the Wadden Islands and the Dutch mainland. The dynamics of the system is mainly modulated by the collective influence of seasonally varying wind, the meso-tidal forcing and the freshwater release from two sluices. A three-dimensional hydrodynamic model (GETM- General Estuarine Transport Model) was applied to this region to study the hydrodynamics of the system for over a period of 11 years. In the present study, we have extracted the depth-averaged current from each inlet that connects the DWS with the North Sea. Furthermore, Simpson-Hunter parameter, which is the ratio between the depth and the cubic power of the current speed, was estimated at each inlet. This empirical formula is adopted to determine the mixing capacity of the DWS inlets on a seasonal and inter-annual scale. The initial results manifested that the Texel and the Vlie inlet undergo well-mixed nature in general; however, sporadic stratification events occur in the low wind condition during slack tide. On a contrary, stratification events occur quite often in the other three inlets (i.e., Eierlandse Gat, Borndiep and Friesche+Pinkegat). On a seasonal scale, the frequency of stratification events in the minimum during autumn and maximum during spring. The present results bear a resemblance to the earlier ones’ where low to intermediate magnitudes of Simpson number (quantification of the density-driven stratification) were obtained in the Texel inlet which is indicative of low stratification. Also, the density-driven stratification was mainly controlled by the wind climatology. On a nutshell, the present research emphasizes the influence of wind on the mixing capacity of the DWS. In addition, further simulations are continued considering the scale of 40 years.
Comparing CO2 and H2O exchange of wetlands (high water table) to crops/forests (low water table)
Authors: Moderow Uta , Grünwald Thomas , Körner Philipp , Bernhofer Christian , Mauder Matthias
Published: February 2023

Today, peatlands only cover slightly more than 3.5 % of Germanys territory. However, they play an important role concerning greenhouse gas emissions (CO2, CH4). We can avoid most of these emissions by proper management of the water table. This leads to a large potential net benefit for climate mitigation when re-establishing valuable long-term carbon sinks at the same time. Measurements in peatlands are challenging because they are often situated in remote locations, and it is difficult to install measurement towers on these statically unstable soils.

Two wetlands in Germany (grey willow in NE Germany; black alder in Eastern Brandenburg) are compared to the TU Dresden cluster of sites close to Dresden. The wetlands receive comparatively little precipitation, e.g. the grey willow site receives on average 580 mm/year (average from 1991 – 2020) but the water table is dominated by the nearby river Peene (fluctuating in dependence of the hydrological conditions in its estuary area). Similar complexity exists for the black alder site with regard to the managed water table of the river Spree. Measurements are available from eddy-covariance since 2010 for the grey willow, and from 2010 to 2015 for the black alder.

Yearly, seasonal and daily data of CO2 (gross primary production, ecosystem respiration) and H2O are analysed relative to the water table and the climate forcing (radiation, vapour pressure deficit and wind). Special attention will be paid to the flux patterns at each site (fingerprints of ET, FC and of WUE). A comparison to the long-term cluster sites (forests, grassland and crop rotation) allows a first assessment of the potential benefit of various land management systems for climate mitigation. However, uncertainty might be large due to the differences in soil and climate, as well as by the typical non-linearity of complex systems like the wetlands and their dependence to the water table.
Source Model of the 2022 Mw6.0 Gölyaka, Düzce (Western Turkey) Earthquake
Authors: Konca Ali Ozgun , Guvercin Sezim Ezgi , Eskikoy Figen
Published: February 2023

On November 23, 2022 an Mw6.0 earthquake struck northwest Turkey. The location of this earthquake is along the boundary of the northeast striking Karadere and east striking Düzce segments of the North Anatolian Fault. Remarkably the area had already ruptured twice during the 1999 Mw7.4 Izmit and Mw7.1 Düzce earthquakes. In this study we analyzed the seismicity, aftershocks and the co-seismic rupture of the 2022 earthquake. Relocated aftershocks reveal a north dipping rupture plane consistent with the previously known fault segments. We modeled the co-seismic slip using InSAR data from Sentinel-1 satellite and near-source seismic waveforms. The kinematic model shows an up-dip bilateral rupture with majority of the slip to the west of the hypocenter.  While the slip is primarily right-lateral there is significant normal component. The fact that the rupture occurred at the junction of two segments, its depth extent and oblique rake angle implies that the 2012 earthquake ruptured along a geometrical complexity that sustained a remanent slip deficit after the 1999 earthquakes.
Sea Surface Temperatures variations during the Messinian in the Sorbas Basin
Authors: Lanterna Francesca , Vasiliev Iuliana , Sierro Francisco Javier , Mulch Andreas
Published: February 2023

In the Mediterranean region, the end of the Miocene is marked by the Messinian Salinity Crisis (MSC; 5.97 - 5.33 Ma), a peculiar event that governed environmental modifications in the region, causing the deposition of large thicknesses of evaporitic rock units, dramatic hydrological and ecological crises that affected both water and land-based habitats. The onset of the MSC has been proven to be synchronous over the Mediterranean basin as demonstrated by astronomical tuning of the pre-evaporitic sedimentary successions. Among these, the Sorbas Basin plays a pivotal role for the understanding of the palaeoceanographic evolution of the Western Mediterranean Sea before the onset of the MSC. Its location within proximity of the Atlantic gateway renders the Sorbas Basin an exceptional recorder of palaeoceanographic changes just prior to the MSC. The pre-evaporitic sequence starts with Tortonian calcarenites (belonging to the Azagador Member) followed by early Messinian clays and diatomites (belonging to the Abad Member). The Lower Abad Member, consists of indurated whitish marls and softer grey marls which contrast sapropel and diatomite alterations of the Upper Abad Member. Here, we present biomarker-based sea surface temperatures (SST) using TEX86 paleotemperatures recorded in the Sorbas basin for the time interval between 7.3 and 6.1 Ma. The TEX86 SST estimates show a generally decreasing trend, with a 7.26 Ma to 7.11 Ma warm phase (averaging 27 °C). This warm phase is followed by ~5°C cooling (to values averaging 22 °C) after 7.11 Ma, with two distinct colder peaks, one centred around 7.09 Ma and one around 6.95 Ma. The cooling after 7.11 Ma follows shallowing and restriction in the Betic and Rifian marine gateways and is most likely controlled by global cooling characterizing the latest Miocene. In a second step, we couple the TEX86 SST estimates with oxygen stable isotope ratios (δ18O) measured on the surface-dwelling planktonic foraminifera Orbulina universa to reconstruct sea surface salinity (SSS) variations at the corresponding stratigraphic levels for the study interval. The newly acquired SST and SSS data from the Sorbas Basin provide a previously unavailable record of changed environmental conditions recorded in the Western Mediterranean Basin that permit direct comparison across the Mediterranean Basin with the recently acquired Messinian Eastern Mediterranean SST and SSS changes.