bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of Fe3+ on the grain growth kinetics of bridgmanite and implications for the lower mantle seismic velocity anomalies
Authors: Fei Hongzhan , Wang Fei , McCammon Catherine , Katsura Tomoo
Published: March 2024

Two large low shear velocity provinces (LLSVPs) near the core-mantle boundary beneath the Pacific Ocean and Africa were discovered about 40 years ago and are characterized by tomographic images as reductions of shear and compression wave velocities by up to 3-4% and 1%, respectively, over an area of several thousand kilometers and a height of more than a thousand kilometers. It was recently proposed that the Fe3+ enrichment in bridgmanite could reduce its shear wave velocity and thus account for the formation of LLSVPs (Wang et al., 2021). However, the viscosity of the Fe3+-enriched bridgmanite is unknown, while it is critical for the long-term stability of LLSVPs at the base of the lower mantle against mantle convection. Considering the operation of diffusion creep in the lower mantle, viscosity will be positively correlated with grain size. Therefore, we measured the grain growth rate of bridgmanite under lower mantle conditions as a function of Fe3+ content. The experimental results show a significant enhancement of grain growth by Fe3+ incorporation. Thus, a larger grain size of bridgmanite is expected in the Fe3+-enriched LLSVPs than in the Fe3+-poor surrounding mantle, leading to highly viscous LLSVPs. As a result, they are stabilized at the base of the lower mantle over geological time.
Machine learning-based regional slant ionospheric delay model and its application for PPP-RTK
Authors: Lyu Sijie , Xiang Yan , Yu Wenxian , Soja Benedikt
Published: March 2024

The precise point positioning-real-time kinematic (PPP-RTK) method achieves fast convergence in global navigation satellite system (GNSS) positioning and navigation. Correcting slant ionospheric delays is crucial for this purpose. The conventional way of obtaining slant ionospheric corrections at the user end involves generating an ionospheric map using a first-order polynomial function or interpolating using methods such as IDW and Kriging. However, with these approaches is challenging to obtain precise and stable ionospheric corrections especially during ionospheric disturbances, potentially degrading the positioning solution even with augmentation. Fortunately, machine learning has the capability to capture complex and non-linear characteristics of diverse data, offering a potential solution to this issue.In this study, we aim to improve the accuracy of slant ionospheric delay models using machine learning and evaluate them in PPP-RTK. Initially, we extract highly precise slant ionospheric delays from carrier-phase measurements after ambiguity resolution for two regional GNSS networks in Switzerland and the South of China. Then, we employ the Gaussian Process Regressor to interpolate epoch-specific and satellite-specific slant ionospheric delays, utilizing latitude and longitude as features. Two different approaches are tested: the direct interpolation from reference stations and the indirect interpolation from a gridded map. Our results indicate that the accuracy of interpolated ionospheric delays using machine learning is higher than with conventional methods, including IDW and Kriging. Finally, we evaluate PPP-RTK positioning results with ionospheric corrections from the different interpolation methods, revealing that the machine learning method exhibits superiority in both positioning accuracy and convergence time over conventional methods.
Reconstruction of the state of stress in the upper crust by borehole breakouts stress indicators
Authors: Pierdominici Simona
Published: March 2024

Knowledge of the present‐day stress field in the Earth's crust is key for understanding the mechanical behaviour of rocks and structures under tectonic forces. The study of stress fields therefore remains a pivotal area for understanding the mechanical behaviour of rocks, fluid flow at depth and in revealing mechanisms that cause tectonic plates to creep, fail, or rupture. stress patterns in the Earth's crust appear on different scales: first order (plate scale), second order (regional scale), and third order (local scale). The latter is mainly controlled by basin geometry, topography, local inclusions, density contrasts, and active faults and can mask regional and plate stress patterns.In this contribution, a couple of examples of stress states at the local, regional and large scale are presented using borehole breakouts as main stress indicator for the current stress field orientation.In order to understand the influence of stress field evolution at local scale, a case study in Hawai´i concerns the effects of the two large overlapping shield volcanoes on the stress field at depth. The analysis reveals that the two-competing gravitational loads primary control the orientation of the present-day stress field, which deviates significantly from the plate and regional tectonic stress field. Therefore, knowledge of local and shallow stress fields can have a significant impact on future borehole planning. From a more regional point of view, an example of current stress orientation in Sweden is presented. The main objectives are to constrain the orientation of horizontal stresses using borehole data, and to discuss implications for geothermal exploration. Thus, obtaining detailed and accurate data on the stress state is of paramount significance to optimise the design of underground installations in order to maximise fluid flow and minimise the risks of wellbore instability. Finally, a large-scale study in Italy investigates the stress field at plate scale to reveal whether the orientation of horizontal stresses may change with depth or laterally indicating stress perturbations and heterogeneities related to areas with complex geo-tectonic setting.In conclusion, this contribution aims to illustrate and emphasise the relevance of determining the horizontal stress orientation at depth in order to improve the understanding of subsurface stress fields and their applications in different fields of geosciences and different geological settings.
Groundwater recharge, vegetation and climate change
Authors: Riedel Thomas , Weber Tobias , Bergmann Axel
Published: March 2024

Groundwater recharge and evapotranspiration are often strongly related to precipitation in temperate regions. However, climate change is expected to change precipitation patterns and alter evapotranspiration, which will inevitably have consequences for the fraction of precipitation that ultimately turns into recharge. Since evapotranspiration is highly sensitive to climate, predictions of future groundwater recharge depend on accurate representation of this parameter. Factors that shape evapotranspiration in vegetated regions are soil water availability, plant water use efficiency, global radiation and vapor pressure deficit, among others, all of which directly or indirectly affect plant water use. How plants adapt their water use to a changing climate is thus highly informative for predictions of future groundwater recharge.Current climate models indicate an increase in potential evapotranspiration, especially under scenarios with strong CO2 emissions. But it is still far from clear whether actual evapotranspiration will also increase, especially in regions where summer-time ET is usually water-limited rather than energy-limited and how this affects recharge.We simulated the consequences of increases in atmospheric CO2 and temperatures for both, evapotranspiration and groundwater recharge, and found that the results are very different for specific vegetations types. For example, some plants will experience an elongation of the growing period, thereby theoretically increasing annual soil water demand. But the growing season for crops may shorten because of faster growing and ripening, so that harvest may occur earlier in the year, thereby decreasing plant soil water demand. Increasing atmospheric CO2 will increase plant-water use efficiency, so that crops may need less water to grow. For trees the picture is even more complicated. Warming spring temperatures may lead to an earlier leafing, but soil water stress at the end the growing season may actually shorten the growing period of trees. Further an increase in leaf area will lead to more transpiration by trees through increased soil-water uptake by roots. But soil evaporation might decrease, as large canopy shading reduces sunlight reaching the ground under trees.The net effect of plant water use and on groundwater recharge is worth studying, especially under the conditions of climate change, because groundwater will likely remain a valuable resource for future human water consumption.
Identifying landscape hot and cold spots of soil greenhouse gas fluxes by combining field measurements and remote sensing data
Authors: Wangari Elizabeth , Mwanake Ricky , Houska Tobias , Kraus David , Gettel Gretchen , Kiese Ralf , Breuer Lutz , Butterbach-Bahl Klaus
Published: March 2024

Upscaling chamber measurements of soil greenhouse gas (GHG) fluxes from point scale to landscape scale remain challenging due to the high variability in the fluxes in space and time. This study measured GHG fluxes and soil parameters at selected point locations (n = 268), thereby implementing a stratified sampling approach on a mixed-landuse landscape (∼ 5.8 km2). Based on these field-based measurements and remotely sensed data on landscape and vegetation properties, we used random forest (RF) models to predict GHG fluxes at a landscape scale (1 m resolution) in summer and autumn. The RF models, combining field-measured soil parameters and remotely sensed data, outperformed those with field-measured predictors or remotely sensed data alone. Available satellite data products from Sentinel-2 on vegetation cover and water content played a more significant role than those attributes derived from a digital elevation model, possibly due to their ability to capture both spatial and seasonal changes in the ecosystem parameters within the landscape. Similar seasonal patterns of higher soil/ecosystem respiration (SR/ER–CO2) and nitrous oxide (N2O) fluxes in summer and higher methane (CH4) uptake in autumn were observed in both the measured and predicted landscape fluxes. Based on the upscaled fluxes, we also assessed the contribution of hot spots to the total landscape fluxes. The identified emission hot spots occupied a small landscape area (7 % to 16 %) but accounted for up to 42 % of the landscape GHG fluxes. Our study showed that combining remotely sensed data with chamber measurements and soil properties is a promising approach for identifying spatial patterns and hot spots of GHG fluxes across heterogeneous landscapes. Such information may be used to inform targeted mitigation strategies at the landscape scale.
Daily heliospheric modulation potential (V23) and modelled GCR dataset compared to space measurements of the GCR energy spectrum.
Authors: Väisänen Pauli , Bertucci Bruna , Tomassetti Nicola , Orcinha Miguel , Duranti Matteo , Usoskin Ilya
Published: March 2024

The activity of the Sun modulates the fluxes of galactic cosmic rays arriving at Earth. This heliospheric modulation of cosmic rays is often quantified by the modulation potential, which describes the average energy loss of particles during their transport in the heliosphere. The modulation potential is a useful parameter not only for understanding the behaviour of energetic particles in the heliosphere, but also as a measure of solar activity. However, the validity of the modulation potential, which utilizes the force-field methodology, is uncertain for shorter timescales, and often the estimates are only monthly or yearly. Recently, an updated estimation of the modulation potential was done at a daily time resolution by utilizing neutron monitor (NM) measurements from 10 stations. We have now analysed the daily version and compared it (via a LIS model) to the variation of the daily GCR energy spectrum (for rigidities 1 to 100 GV) measured by the AMS-02 instrument in the ISS. We find that overall, the daily modulation potential works well for estimating daily count rates at different energies. The correspondence is lowest for the low energy bins, where we see an excess of particles, which seems to follow the solar cycle. For rigidities around 4-13 GV, we can see a very clear match, letting us estimate daily count rates for different energy bins with a few per cent accuracy. For higher energies, the noise background of the measurements masks the underlying variation.The result is very interesting and promising for the feasibility of using the modulation potential estimates for shorter time scales. This will lead to a better understanding of the variability of the overall modulation and the possibility of utilizing and combining NM and spacecraft measurements. The results will be useful in space climate (e.g. long-term solar variation induced from cosmogenic isotopes) and space weather (e.g. CME's/Forbush decreases, CIR's, Flares/GLE's) research. Future work with additional datasets and analysis of the different LIS models is planned.
Climatology, characteristics and forcing mechanisms of warm-season cold-frontal convection in Europe
Authors: Pacey George , Pfahl Stephan , Schielicke Lisa , Wapler Kathrin
Published: March 2024

Convection frequently initiates in proximity to cold fronts during the European warm-season and can also be associated with hazards such as flooding, rain, and hail. Despite this, the frequency and underlying processes that drive such events are not well-understood. To understand the typical nature, frequency and forcing mechanisms of convection depending on the region relative to the front, automatic front detection methods, a convective cell detection and tracking dataset (KONRAD), and lightning data are combined between 2007–2016.The climatology shows that convective cells are most frequent in Germany marginally ahead of the surface front. Furthermore, the 700 hPa frontal line marks the minimum frequency of convection and a shift in regime between cells with a strong diurnal cycle on the cold-side of the 700 hPa front and a weakened diurnal cycle on the warm-side of the 700 hPa front. The results are consistent for lightning data on a sub-European domain. Given cell detection ahead of the surface front, cells are up to 3 times more likely to be associated with a mesocyclone compared to non-cold-frontal cells in Germany. Cells with 55 dBZ cores are over 1.5 times more likely.To unravel the complex relationships between different predictor variables and the probability of convection a logistic regression model is developed. Feature importance techniques are utilised to understand which variables carry the most importance depending on the region relative to the front. We find solar heating carries more importance towards the model’s predictive power behind the 700 hPa front than ahead of the 700 hPa front. The opposite is true for the elevation term, which acts as a proxy for the influence of orography on convective initiation. By giving the model information on the number of surrounding grid points associated with convection, a proxy for cell interactions, the most skill is added near the surface front.These results are an important step towards a deeper understanding of the underlying processes that drive cold-frontal convection and improved forecasting.
Can Venus and Mars Inform Us About Intraplate Magmatism on Earth?
Authors: King Scott , Duncan Megan , Euen Grant , Murphy Joshua , Parrish Savaria , Weller Matt
Published: March 2024

Venus and Mars have operated as one-plate planets for some or all of their history and intraplate magmatic activity on Earth has been suggested as an analogue for the observed volcanic activity on these bodies. Flipping the question around, what can we learn about intraplate magmatism on Earth from other planets?Volcanic features, including extensive lava flows and vast lava plains, cover large portions of the Martian surface. Mars has two large volcanic provinces: Tharsis and Elysium. While the continent-sized region of elevated terrain called the Tharsis rise receives most of the attention, Elysium—the second largest volcanic province on Mars—is larger than the Ontong-Java plateau—the largest LIP on Earth. Activity detected by the InSight seismometer near Cerberus Fossae (located in Elysium Planitia, southeast of the Elysium volcanic province) is consistent with fluid flow at depth. Cerberus Fossae is among the youngest tectonic structures on Mars and large discharges of water and lava have been proposed to explain the geomorphic structures observed at Cerberus Fossae. The regional gravity and topography, volcanic history, and seismic activity at Cerberus Fossae are consistent with a present-day 2,000-km-radius plume head beneath Elysium Planitia. The characteristics of the Elysium Planitia plume are comparable to terrestrial plumes proposed to explain the formation of terrestrial LIPs. Plumes on Mars appear to be spatially stable for long periods of time, reflecting the stabilizing influence of a thick stagnant lid and sluggish mantle convection.While Venus is nearly the same size as Earth, there is no evidence supporting Earth-like plate tectonics for the past 250-750 Myrs. The similarity in size invites comparison of present-day volcanic activity between the two planets. This is complicated by the presence of plate tectonics where volcanic activity at ridges and subduction zones has no clear analogue on Venus. Expanding intraplate volcanism on Earth suggests as many as 100 active volcanic events per year on Venus. While detecting surface changes is one goal of the upcoming NASA and ESA Venus missions, surface change associated with volcanic activity has already been found in the Magellan image archive. Herrick and Hemsley identified a 2 km2 volcanic vent that changed shape in the eight months between two Magellan radar images. While sulfuric acid clouds obscure our view of the surface, those same clouds provide the best evidence for ongoing volcanic activity. Assuming the primary mechanism removing atmospheric SO2 is a reaction between calcium minerals on the surface and SO2, an SO2 residence time of ~2 Myrs is required. This requires an outgassing rate of ~6x1010 kg SO2/year—about the same yearly SO2 outgassing rate measured on Earth over the past decade. Converting this outgassing rate to erupted lava, an eruption rate on Venus of ~1 km3/yr is obtained.
Arase HEP-L electron measurement calibration and comparisons of pitch angle distributions with Van Allen Probes
Authors: Kalliokoski Milla , Asamura Kazushi , Shinohara Iku , Mitani Takefumi , Hori Tomoaki , Miyoshi Yoshizumi , Higashio Nana , Takashima Takeshi
Published: March 2024

The Arase satellite observes the dynamics of the Earth’s radiation belts, including the electron fluxes over a wide energy range from a few electronvolts to several MeV. This work focuses on the measurements of the Arase high-energy electron experiment (HEP), specifically its instrument HEP-L that observes electrons from 60 keV to 1.5 MeV. It is a state-of-the-art instrument capable of distinguishing the incoming direction of electrons by position sensitive detectors, thus accurately determining the pitch angle. HEP-L has been previously calibrated based on the modeled response functions of the instrument’s energy channels using Geant4 simulation. The current work utilizes the same simulation, but now considering the calibration in terms of the azimuthal channels, i.e., the direction of measured counts. As shown by the simulation, the distribution of counts in each azimuthal channel is broader than the nominal range in the initial direction angle, causing cross-channel contamination. We propose a new method to calibrate HEP-L data to diminish this contamination, and applying the correction method lowers the electron fluxes especially at field-aligned pitch angles, where uncorrected HEP-L data were overestimated, as seen in comparison with other instruments on board Arase and the Van Allen Probes. Pitch angle distributions (PADs) from Arase and Van Allen Probes were compared during close conjunctions of the spacecraft. Previous comparisons have only considered the omnidirectional fluxes which offer a limited view of the radiation belt dynamics. PADs provide a more detailed comparison and shed light on, e.g., wave-particle interactions. Here we derived PADs from HEP-L and extremely high-energy experiment (XEP) on Arase, and the Magnetic Electron Ion Spectrometer (MagEIS) and the Relativistic Electron-Proton Telescope (REPT) instruments on Van Allen Probes to cover a large energy range. There is a remarkable agreement within a factor of 2 for all energies, for all pitch angles for XEP data and for most pitch angles (20 to 160 degrees) for uncorrected HEP-L data. By applying the new correction, the discrepancy at the field-aligned pitch angles is reduced.
The Absolute Gravity Reference Network of Italy
Authors: Barzaghi Riccardo , Riguzzi Federica , Greco Filippo , Berrino Giovanna , Germak Alessandro , Mazzoni Augusto
Published: March 2024

The project for realizing the reference network for absolute gravity in the Italian area is presented. This fundamental infrastructure is the general frame for all the scientific and technological activities related to the gravity field in Italy. The project is in line with the actions promoted by the International Association of Geodesy that during its 2015 General Assembly approved a resolution on the establishment of the new global gravity network the so-called International Terrestrial Gravity Reference System/Frame that will replace IGSN71.The selection of the absolute gravity station sites in Italy has been performed either taking into account the existing absolute gravity stations and to have a homogeneous distribution of points. An initial set of 30 stations has been defined over the peninsular part of Italy and the two islands of Sicily and Sardinia. Particularly, the GGOS core station of Matera (the Agenzia Spaziale Italiana Center for Space Geodesy “Bepi” Colombo) is one of the network points as required in the documents of the GGOS-Bureau of Networks and Observations. Thus, this station will provide one link between the Italian national absolute gravity network and the GGOS observation system of IAG.The project is now ongoing and will close at the beginning of 2025.As required by the international standards on gravity measurements (https://www.bipm.org/documents/20126/41442296/CCM++IAG+Strategy+for+Metrology+in+Absolute+Gravimetry/7f9bc651-a2b6-08cc-7bba-f63b0a7e9765), the absolute gravimeters used in the measurements have been compared with absolute gravimeters that participated into international comparison campaigns in order to ensure the measurements traceability.Furthermore, absolute gravity measurements have been supplemented with direct measurements of the local value of the vertical gravity gradient, in order to reduce to the ground reference level the absolute values measured by different instruments at different heights. The gravity field campaigns will be assisted by topographic survey campaigns. This will allow a precise georeferencing (of the order of 12 cm) of the gravity stations that will be so framed to the current ITRF.The collected data will be then validated and reduced following the internationally accepted standards and finally published through a dedicate web page of the project. These data will also be sent for storage to the absolute gravity database maintained by the Bureau Gravimétrique International/Bundesamt fuer Kartographie und Geodaesie where the absolute gravity data that will contribute to the new global absolute gravity reference system are collected.
Sedimentation rate decrease in the Skagerrak and its implication for human and natural impacts in the North Sea
Authors: Spiegel Timo , Dale Andrew W. , Lenz Nina , Schmidt Mark , Fuhr Michael , Kalapurakkal Habeeb Thanveer , Moros Matthias , Lindhorst Sebastian , Wolschke Hendrik , Kasten Sabine , Butzin Martin , Mollenhauer Gesine , Mueller Daniel , Wallmann Klaus
Published: March 2024

Since industrial times, human and natural processes have affected the sediment system of the North Sea. As a substantial proportion of the suspended sediment in the North Sea is ultimately deposited in the Skagerrak, it offers a representative archive for reconstructing the temporal variability of the North Sea sediment system. However, little is known about how sedimentation rates in the Skagerrak may have changed over time. In this study, we present high-resolution age-depth models based on the natural radionuclide 210Pb and the anthropogenic time markers 137Cs, 14C and mercury to determine average sedimentation rates before and after the year 1963 at six stations in the Skagerrak. This year was selected because its age-depth relationship was clearly reflected by peak activities or concentrations in the sedimentary data of the time markers. The main result of this study is a consistent decrease in sedimentation rates at all stations. On average, sedimentation rates decreased from 0.36 to 0.15 cm yr-1, suggesting a substantial alteration of the North Sea sediment system. We tentatively discuss possible driving factors including a shift in the North Sea circulation pattern, increased sediment deposition in the Wadden Sea, and reduced sediment inputs into the North Sea due to coastal protection and river damming. In terms of the overall North Sea sediment cycle, these processes may outweigh the effects of sediment resuspension by human activities and storm events, as well as temperature, humidity and sea level rise caused by climate change.
Critical role of vertical radiative cooling contrast in triggering episodic deluges in small-domain hothouse climates
Authors: Song Xinyi , Abbot Dorian , Yang Jun
Published: March 2024

Seeley and Wordsworth (2021) showed that in small-domain cloud-resolving simulations the temporal pattern of precipitation transforms in extremely hot climates (≥ 320 K) from quasi-steady to organized episodic deluges, with outbursts of heavy rain alternating with several dry days. They proposed a mechanism for this transition involving increased water vapor greenhouse effect and solar radiation absorption leading to net lower-tropospheric radiative heating. This heating inhibits lower-tropospheric convection and decouples the boundary layer from the upper troposphere during the dry phase, allowing lower-tropospheric moist static energy to build until it discharges, resulting in a deluge. We perform cloud-resolving simulations in polar night and show that the same transition occurs, implying that some revision of their mechanism is necessary. We perform further tests to show that episodic deluges can occur even if the lower-tropospheric radiative heating rate is negative, as long as the magnitude of the upper-tropospheric radiative cooling is about twice as large. We find that in the episodic deluge regime the period can be predicted from the time for radiation and reevaporation to cool the lower atmosphere.
Irish Peatland Resilience and Presence Across National Climate Gradients 
Authors: Sabokrouhiyeh Nima , Van der Velde Ype , Connolly John , Kettridge Nicholas
Published: March 2024

Peatlands are essential for providing crucial ecosystem services such as carbon sequestration, water regulation, and biodiversity conservation. However, in Ireland, these vital ecosystems have undergone significant degradation due to practices like land use alterations, drainage, and peat extraction activities. The collective impact of these disturbances, amplified by the influence of climate change, presents a substantial threat to the resilience of Irish peatlands. Here we evaluate the impact of climate gradients on Irish Peatland Resilience at a national scale through the application of a mechanistic model. We identify critical tipping points that signify shifts between peatlands and forests and assess how these vary with climate, and how these impact ecosystem carbon stores. Through  this approach we delineated various peatland types prevalent in Ireland, such as western blanket bogs, mountain blanket bogs, and raised bogs. Furthermore, model outputs were used to derive the resilience index for these diverse peatland systems, providing an indication of their capacity to withstand environmental changes. The insights from this research offer valuable guidance to help target national peatland restoration strategies. Ultimately, this study contributes to the broader goal of sustainable peatland management and preservation amidst changing environmental conditions.
Detection of noise in supervised label data: a practical approach in the Amazonas region of Brazil using land use and land cover maps
Authors: Hell Maximilian , Brandmeier Melanie
Published: March 2024

The region of Amazônia Legal in Brazil is in constant change due to deforestation and degradation of forest and conversion into arable land to use for farming or cattle ranching. It is important to monitor these changes with respect to global climate change and to aid political decision makers. These changes are best captured and analyzed through openly accessible satellite data, such as the products of ESA's Sentinel Missions. Land use and land cover (LULC) classification is often performed on remotely sensed data through supervised learning algorithms that rely on precise labels to produce accurate results. However, this kind of data is often not available and it is a time consuming task to create such data at the required accuracy level through image interpretation. This can be alleviated by using existing LULC maps from other sources such as the classification maps produced by the MapBiomas Brasil project used in our project. These maps are created using Landsat time series data and multiple machine and deep learning models to classify the whole of Brazil into five macro and multiple micro classes. This data has it's own bias and is not correct in all places or highly inaccurate, especially compared to data which is higher in spatial resolution -- as the aforementioned Sentinel data -- and reveals more detail in the land coverage. Thus, it is a critical step to investigate the noise in the label data. There are multiple approaches in the relevant literature to tackle learning with noisy labels, most of these approaches rely on robust loss functions or learned models to identify the noise. We present a novel approach where the satellite imagery is split pixel-wise in the prior given five macro class labels. For each class, a self-organizing map (SOM) is learned to cluster the data in the spectral domain and thus identify representative prototypes of each class. Each class is represented by the same number of prototypes, which overcomes the problem of imbalanced classes. The labels are then checked through neighborhood rules if they belong to their given class or are labeled as unsure or even switch classes otherwise. In our study, approx. 79.5% of pixels keep their given class, while the rest is reassigned or even discarded. To validate the approach, the results are compared to a manually created validation set and inspected visually for qualitative correctness. The MapBiomas LULC maps reach an overall accuracy of 62.6% in the created validation areas. After relabeling the data with the presented approach, the overall accuracy reached a score of 81.3%, showing a significant increase. This approach is independent of a specifically learned model and only leverages on the relationship between the training data and the given label data --- the Sentinel-2 imagery and the MapBiomas LULC map, respectively.
Future changes in spatially compounding hot, wet or dry events and their implications for the world's breadbasket regions
Authors: Biess Bianca , Gudmundsson Lukas , Windisch Michael , Seneviratne Sonia I.
Published: March 2024

Recent years were characterized by spatially co-occurring hot, wet or dry years around the globe. Spatially compounding extreme events can strongly amplify societal impacts as economic supply chains are increasingly interlinked, highlighting the increasing importance of advancing our knowledge of the effects of human-induced climate change on such events. We assess the occurrence of spatially compounding hot, wet and dry years under different future warming levels of 1.5°C , 2°C, 3°C and higher levels of global warming. We focus our analysis on the top-producing agricultural regions that have historically provided the global food systems with large quantities of wheat, maize, soybean or rice. The occurrence of spatially compounding events and area affected in future climates is determined using Earth System Model simulations from the 6th Phase of the Coupled Model Intercomparison Project (CMIP6). The simulations project a strong increase in the global land area that is concurrently affected by hot, wet and dry extremes under continued global warming. On regional scales, the world’s breadbasket regions are particularly affected by strong increases in the simultaneous occurrence of hot, wet or dry extremes under continued global warming. The spatial extent of agricultural land potentially threatened by climate extremes will increase drastically if global mean temperatures shift from +1.5 °C to +2.0 °C, and will be further amplified with every tenth of degree of warming. This highlights that ambitious climate action needs to be taken in order to limit global warming if we want to keep the global agricultural land in a safe climatic space.
The Application of Transformers and Hybrid Deep Learning Models for Streamflow Forecasting 
Authors: Ahmed Ashaf , Abdoulhalik Antoifi
Published: March 2024

Hybrid machine learning (ML) models have exhibited great forecasting accuracy across all water-related fields, often showing promising greater performance and computational power over standalone ML algorithms. Meanwhile, transformers have demonstrated remarkable capabilities in natural language processing tasks due to their attention mechanism; their application to time series forecasting, particularly in hydrology or streamflow prediction, is an evolving area. This study compared the performance of Transformers to various hybrid deep learning models in forecasting river streamflow data in Syr Daria. The hybrid models included LSTM with attention mechanism (LSTM-AM), LSTM with Arima (LSTM-AR), and Convolutional Neural Networks combined with LSTM (ConvLSTM). The forecasting performance of each model was tested at three hydrological stations located upstream, midstream, and downstream along the Syr Darya River, respectively. The forecasting performance was evaluated by comparing RMSE, MAE, NSE and KGE values achieved by each model. The streamflow datasets exhibit short-term dependencies that LSTM models can capture effectively, while transformers are more parameter-intensive than LSTMs. Simpler models like LSTMs perform relatively well and achieve comparable predictive accuracy to hybrid models. While LSTM-based models are found to be better suited for short-term forecasting, the transformer model tends to excel in longer-term predictions as they are better at capturing long-range dependencies in sequences. Nonetheless, all the models exhibit a decrement in predictive performance with an increasing forecasting horizon. The findings of this study evidence the suitability of transformers for high-performance and budget-wise river flow forecast applications while minimising data processing time.
Soil particle size distribution using the integral suspension pressure method (ISP) and gamma-ray spectrometry techniques for soil texture mapping.
Authors: Trust Brenda , Toloza Arsenio , Mitchell Jason , Konzett Matthias , Said Ahmed Hami , Mbaye Modou , Dercon Gerd , Strauss Peter
Published: March 2024

Understanding the role of soil texture in soil-water management amid climate change is crucial for sustainable agriculture as it influences water availability, nutrient dynamics, erosion control, carbon sequestration, and overall soil health. Therefore, having soil texture mapping is an important decision tool for establishing sustainable resource management.In this study, we present findings from soil sampling conducted in 2023 and a decade earlier from Hydrological Open-Air Laboratory (HOAL) in Petzenkirchen, Lower Austria. The PARIO system was used to analyse soil particle distribution utilising the Integral Suspension Pressure (ISP) method. This method utilizes the stokes’ law to calculate the particle size distribution based on changes in suspension pressure and temperature. The change of suspension pressure as well the temperature is measured at 10- seconds intervals following the chemical and physical dispersion, along with the pretreatment of soil samples involving the removal of organic matter, soluble salts and determination of sample dry weight. The analysis of soil texture from the 2023 soil sampling, conducted using the PARIO system, revealed a predominant silty clay loam structure, with a particle distribution of 9% sand, 56% silt, and 35% clay, aligning closely with results from a decade prior. Concurrently, we utilized Gamma-Ray Sensor (GRS) technology to measure the spatial activity concentrations (Bq.kg-1) of 40K (potassium), 238U (uranium), and 232Th (thorium) over more 20 points across the fields. The aim was to correlate these radionuclide concentrations with soil texture data using a Python-based correlation model. Preliminary results showed the best correlation between 40K radionuclide concentrations versus clay (R2 = 0.8) and silt (R2 = 0.7) and 238U versus silt (R2= 0.7). Thus, spatial monitoring of 40K and 238U with mobile GRS can be used for spatial determination of clay and silt. Nevertheless, further analysis is essential to compare and validate these results with a more extensive dataset encompassing additional soil texture data.These preliminary results demonstrate the potential of monitoring 40K and 238U concentrations by a portable gamma sensor for soil texture mapping in agricultural land. Further analysis and validation are required to verify the robustness of this model.
Sub-shelf melt patterns… does detail matter?
Authors: Jesse Franka , Lambert Erwin , van de Wal Roderik
Published: March 2024

Observations show that some of the ice shelves surrounding Antarctica are thinning, driven by warming of the underlying ocean. These ice shelves play an important role in moderating the rate of mass loss from the ice sheet by buttressing the ice flow from the grounded parts of the ice sheet. The increased ocean-induced sub-shelf melt is therefore an important process for the stability of the ice sheet and representing it in ice sheet models is essential to study the evolution of the Antarctic Ice Sheet. Here, we present a coupled ice-ocean setup, applied to an idealised ice shelf.The sub-shelf melting occurs in highly heterogeneous patterns, typically exhibiting higher melt rates near the grounding line. Currently, most ice sheet models rely on parameterisations which derive sub-shelf melt rates from far-field ocean hydrography. Despite their computational advantage and ease in handling grounding line migration, these parameterisations fall short of accurately representing the right details in the melt patterns. To capture more physically consistent melt patterns, we implemented an online coupling between the ice sheet model IMAU-ICE and the sub-shelf melt model LADDIE. The latter resolves the necessary physics governing the melt, including the Coriolis deflection and topographic steering of meltwater, and provides sub-shelf melt fields at sub-kilometre spatial resolution.We will show the impact of detailed sub-shelf melt fields in an idealised set-up. We compare IMAU-ICE simulations using existing sub-shelf melt parameterisations with simulations in the coupled set-up with IMAU-ICE and LADDIE. Three parameterisations are considered for this comparison: the quadratic scaling with temperature, the box model PICO, and the plume model. All simulations are performed in the idealised MISMIP+ domain. We consider a range of oceanic temperature forcings similar to present-day temperatures in warmer and colder basins surrounding Antarctica. We present and discuss the results, primarily focusing on the evolution of three key indicators for ice sheet stability: grounding line position, ice shelf extent, and grounding zone shape. These results demonstrate the importance of accounting for realistic melt patterns in ice sheet models.
IRIS: Global Reach-Scale River Surface Slopes from the ICESat-2 Satellite 
Authors: Scherer Daniel , Schwatke Christian , Dettmering Denise , Seitz Florian
Published: March 2024

We present the latest version of the global reach-scale “ICESat-2 River Surface Slope” (IRIS) dataset, which comprises average and extreme water surface slopes (WSS) derived from observations of the ICESat-2 satellite between October 2018 and August 2023 as a supplement to 130,283 reaches from the “SWOT Mission River Database” (SWORD). To gain full advantage of ICESat-2’s accurate and unique measurement geometry with six parallel lidar beams, the WSS is determined across pairs of beams or along individual beams, depending on the intersection angle of spacecraft orbit and river centerline. Combining both approaches maximizes spatial and temporal coverage. IRIS can be used to research river dynamics, estimate river discharge, and correct water level time series from satellite altimetry for shifting ground tracks. Additionally, we compare IRIS with observations from the recently launched SWOT mission. 
Transient deformation leading to earthquakes: bridging observations from the lab and the field 
Authors: Martínez-Garzón Patricia , Kwiatek Grzegorz , Poli Piero , Dresen Georg , Bohnhoff Marco
Published: March 2024

A longstanding question in geoscience concerns whether earthquakes show a preparatory process and precursory seismic activity. Some models hold that in the intermediate-term (from months to years), seismicity and/or aseismic transients in fault slip and in other fault properties occur. During the last decades, improvements in earthquake monitoring, the integration of geodesy capturing slow deformation, and the incorporation of novel data analysis techniques including machine learning and artificial intelligence have improved our ability to better discern how earthquake sequences evolve before a mainshock. The few available observations of transient deformation preceding well-recorded earthquake sequences show a high variability, thus our potential for improving earthquake forecasting is still limited. The body of knowledge available from mechanical models, numerical simulations, experimental work and field observations highlighted a wealth of structural, tectonic and boundary conditions which may control the dynamics of earthquake sequences. These suggest that several processes can affect earthquake preparation on different temporal and spatial scales, ultimately yielding highly varying transient observations prior to mainshocks. These observations also highlight that existing theoretical and conceptual models of the preparation/nucleation process may not fully capture the governing physics.We analyzed seismicity transients prior to the occurrence of the 2023, MW 7.8 Kahramanmaraş/Türkiye earthquake. We identified seismic precursory activity composed of a handful of isolated spatio-temporal clusters occurring in a complex fault network within 65 km of the future earthquake epicenter. Some of these clusters contributed to acceleration of seismicity rates in an area surrounding the future mainshock and starting ca. 8 months before the event. Within that area, we also observed a decrease in Gutenberg-Richter b-values. Comparable seismic transients were not observed in the region at least since 2014. The complex preparatory process differs significantly from the cascade of close (
Antarctic sea ice sensitivity to the orographic gravity wave drag in a fully coupled climate model 
Authors: Guarino Maria Vittoria , Ridley Jeff , Farneti Riccardo , Kucharski Fred , Tompkins Adrian
Published: March 2024

Low-level winds over Antarctica are overwhelmingly controlled by the local orography. They, in turn, exert a large control on sea ice formation and transport.In Global Circulation Models, the influence of orography on the climate system is modelled via orographic gravity wave drag (OGWD) parameterizations. Models usually partition the drag exerted on the atmosphere by the sub-grid scale orography into two components due to flow blocking and gravity waves.In this work, we investigate the relationship between Antarctic sea ice and the parameterized OGWD in the UK Earth System Model (UKESM). We present results from sensitivity tests performed using the UKESM-CMIP6 historical runs.In these simulations, the partition between the “flow-blocking” component and the “gravity wave” component of the OGWD parameterization was altered to simulate “flow-over” and “flow-blocking” regimes. These experiments show that sea ice strongly responds to changes in the orographic gravity wave drag. The strong sea ice decline simulated by the control run from 1980 to 2015, not matched by the observational record, is halted and is delayed by 15-20 years (across the ensemble members) in our flow-blocking regime simulation. Conversely, in the flow-over regime simulation, sea ice begins declining about 10 years earlier than in the control run. The systematic response of the coupled system suggests the existence of a dynamical relationship between sea ice and OGWD.The pan-Antarctic signal for sea ice decline derives from the Weddell Sea sector. The pathway through which OGWD influences sea ice is via modifications of the flow regime across the Antarctic Peninsula, and thus the surface wind stress across the Weddell Sea sector, which in turn alters the occurrence of oceanic deep convection. This happens because the flow regime across the Antarctic Peninsula is critical in determining the strength and pattern of the surface winds on both the windward side (Bellingshausen and Amundsen Seas sector) and the lee side (Weddell Sea sector) of the mountain ridge.
Indo-Pacific basin interactions and their impacts on Austral-Asian hydroclimate over the last millennium
Authors: Wang Shouyi , Ummenhofer Caroline , Oppo Delia , Denniston Rhawn
Published: March 2024

Rainfall associated with the Austral-Asian monsoons affect the livelihoods of over half of the world’s population, yet the impacts of anthropogenic forcings on regional hydroclimate trends in the coming decades remains uncertain. Observation-based studies have found that monsoonal rainfall over Austral-Asia is influenced on interannual-decadal timescales by tropical sea surface temperature (SST) patterns in the adjacent Indian and Pacific Oceans. In recent years, interactions between the tropical Indian and Pacific Ocean (tropical basin interactions) have been recognized as important in understanding Austral-Asian hydroclimate variability. However, instrumental observations are too short to clarify the relationships between Austral-Asia rainfall and Indo-Pacific basin interactions on longer (multidecadal-centennial) timescales.Here we utilize last millennium climate model simulations, Indo-Pacific SST and hydroclimate multi-proxy (e.g., stalagmites, corals, marine and lacustrine sediments) archives and various climate field reconstruction methods (e.g., composite plus scale, offline data-assimilation) to investigate low-frequency tropical basin interactions over the last millennium. Specifically, we assess whether the zonal SST gradients in the Indian and Pacific Oceans, which reflect basin-wide Walker Circulation strength, are coupled on multidecadal-centennial timescales. Preliminary analysis suggests intervals of decoupling between the two basins which coincided with simultaneous changes in the strength of the Australian and Asian monsoons. These findings provide dynamical insights into interpreting hemispherically in-phase hydroclimate records as well as long-term context for climate-risk management over Austral-Asia.