bluuebunny/crossref_metadata_2025 huggingface dataset:
Innovative Insights into Earth's Interior: Moho Topography Estimation using Conditional Generative Adversarial Networks from Observed Gravity Anomalies 
Authors: Roy Arka , Sharma Rajat Kumar , Jash Dharmadas , Kallukalam Tomson J
Published: March 2024

Precise determination of Moho topography holds paramount importance in advancing our comprehension of Earth's structural characteristics, geodynamic phenomena, and the exploration of resources. This study introduces an innovative methodology employing conditional Generative Adversarial Networks (cGAN) to unveil Moho topographies from observed gravity anomalies. To address the scarcity of real Moho datasets for training the cGAN model, we meticulously generated a comprehensive set of quasi-realistic synthetic training data using the FFT filtering technique. The forward estimation of gravity anomalies, arising from synthetic Moho topographies, was assessed through spherical prism-based gravity modeling. These estimated anomalies served as input data for the training of the cGAN model. For evaluating the efficacy of our developed cGAN algorithm in deriving Moho architecture, we conducted a comparative analysis against a conventional inversion scheme. This assessment utilized various synthetic datasets and a real case study in Southern Peninsular India, renowned for its geological diversity and ancient continental tectonic blocks. The established Bott's inversion scheme was employed as a benchmark to validate the Moho surface estimation obtained through the Deep Learning approach. To mitigate the impact of diverse factors such as topography, bathymetry, sediments, crustal and mantle heterogeneities, observed gravity anomalies underwent meticulous corrections using spherical prism-based forward gravity modeling for real case studies. The gravity contribution exclusively associated with the pure Moho was subsequently inverted using both the cGAN and traditional Bott's inversion schemes. Crucial hyperparameters, including the mean Moho depth and density contrast between the crust and mantle, were determined by utilizing seismic constraints. Our results underscore the potential of the cGAN and spherical prism-based gravity modeling approach in accurately predicting Moho topography. This study provides valuable insights into high-resolution Earth's Moho architecture and contributes to advancing our understanding of geodynamic processes, facilitating resource exploration endeavours with reduced computational demands.
The Need for Utilizing AI in Locating Trapped Victims Following Earthquakes and Floods
Authors: Avny Ronnen , Friedman Menachem
Published: March 2024

The present article delves into the necessity of employing artificial intelligence (AI) in locating individuals trapped during natural disasters such as earthquakes and floods. By utilizing unmanned equipment for reconnaissance and support tasks during search and rescue missions, lives can be saved, and the process expedited. Natural disasters have resulted in significant financial losses and loss of human lives, making it imperative to develop efficient and effective methods for rescue operations. The article emphasizes the benefits of using Trapped Victims Location (TVL) systems, including improved response times, increased accuracy, enhanced situational awareness, and improved safety for first responders. Furthermore, the article discusses the current TVL technologies available, such as visual cameras, acoustic sensors, thermal imaging cameras, radar sensors, GPRS, Cellular receivers, and more. The article also highlights the operational gaps within first responders' systems for locating trapped victims and discusses the specific operational needs for various scenarios. This work serves as a basis for further scientific and engineering projects that can overcome existing gaps and enhance the operational process of locating victims during emergencies, significantly improving accuracy and the likelihood of locating live individuals while expediting the entire procedure.
The North Atlantic climate variability in single-forcing large ensemble simulations with MPI-ESM-LR
Authors: Pohlmann Holger , Müller Wolfgang A.
Published: March 2024

The origin of multi-decadal climate variability in the North Atlantic is under debate. The variability could be caused by oceanic internal variability or by external anthropogenic or natural forcing. We have produced a set of single-forcing historical simulations with the Max Planck Institute - Earth System Model (MPI-ESM) in low resolution (LR). The historical-like simulations consists of 30 ensemble members and the external forcing is from the Coupled Model Intercomparison phase 6 (CMIP6). Each set of simulation is forced by either only greenhouse-gases, total ozone, solar insolation, anthropogenic aerosols or volcanic aerosols. We present first results of our attribution of the climate signals in the North Atlantic region to the different single forcings.
Using magnetic field observations from the Galilean moons to diagnose ocean properties
Authors: Dougherty Michele
Published: March 2024

One of the most important realizations that planetary scientists have come to in the last 20 years is that in the search for potential habitability in our solar system, the focus need not only be on planetary bodies close to the Sun, where water on the surface is in liquid state. Based on Galileo and Cassini observations in the Jupiter and Saturn systems, there are many potential places in our solar system where sub-surface liquid water oceans may exist.JUICE magnetometer (J-MAG) measurements (such as those made by the magnetometers on the Galileo and Cassini spacecraft) enable an understanding to be gained of the interior structure of the icy moons of Jupiter, specifically those of Ganymede, Callisto and Europa. Of particular interest are knowledge of the depth at which the liquid oceans reside beneath their icy surfaces, the strength of any internal magnetic fields such as at Ganymede and the strength of any induced magnetic fields arising within these oceans.The primary science objectives of JUICE which will be constrained by the magnetic field observations and which drove the performance requirements of the J-MAG instrument include:At Ganymede:
Characterization of the extent of the ocean and its relation to the deeper interior
Characterization of the ice shell
Characterization of the local environment and its interactions with the Jovian magnetosphere
Description of the deep interior and magnetic field generation
At Europa, further constrain the depth of the liquid ocean and its conductivity
At Callisto, characterize the outer shells, including the ocean
 
Comparison of the reference periods of the hydrological years 1981 - 2010 and 1991 - 2020 in groundwater in Slovakia
Authors: Kurejova Stojkovova Michaela , Slivova Valeria
Published: March 2024

In the Slovakia for assessment of climate change is used as references period hydrological years 1981 - 2010. Although the first observations in groundwater began in 1956, the monitoring network was not dense enough and the objects were not evenly distributed in Slovakia. Even the expansion of monitoring network in the 1970s was not enough to obtain longer, 30-year time series. Based on the new reference period 1991 - 2020 recommended by the World Meteorological Organization WMO, this period was also evaluated from the point of view of groundwater. The aim of the contribution was to compare reference periods 1981 – 2010 and 1991 - 2020 and their changes in the groundwater in Slovakia. These two reference periods were compared with each other based on the ratio values of long-term time series of minimum and average values of the groundwater level and springs yield. The new reference period 1991 - 2020 and period 1981 - 2010 were also evaluated by trend analysis using the non-parametric Mann-Kendall test. The Mann-Kendall statistical test was use to assess whether a set of data values is increasing or decreasing over time and whether the trend in either direction is statistically significant. The Mann-Kendall test does not assess the magnitude of change. The advantage of this test is, that it is not affected by the current distribution of the data and at the same time is less sensitive to extreme values in the time series.                The long-term average values of the groundwater level and the springs yield for the period 1991 - 2020 compared to 1981 - 2010 were lower in the outer West and Northwest, in the Northern parts of Slovakia, in the region of central Slovakia, and in the Southeast and outer East. Based on the comparison of the long-term minimum values of the compared periods, the values were steady in compared to the previous period at most of the evaluated objects.                When evaluating the trends of long-term averages for the period 1991 - 2022, significant decreases in the average groundwater level and springs yield were detected in the outer West and Northwest, in the strip from Northern to central Slovakia, in the North of Eastern Slovakia, and in the Southeast and outer east of the territory. When evaluating the trends of long-term minima for the period of hydrological years 1991 - 2022, the situation was similar to the evaluation of long-term averages.                By comparing the period of 30 annual series 1991 - 2020 to the period 1981 - 2010 based on the evaluated ratio values, we did not notice significant deviations. Keywords: groundwater, spring yield, references periods
Evaluation of the K-scale model hierarchy across MetOffice models.
Authors: Sanchez Claudio , Lewis Huw , Jones Richard , Warner James , Shchepanovska Dasha
Published: March 2024

Models resolving km-scale processes, such as deep convection, improve the representation of precipitation associated to several processes at sub-synoptic scales, e.g. diurnal cycle, mesoscale convective systems or tropical cyclones. These models generally improve extremes and add value to hazard forecasting, in particular over the tropics. However, these models have been unaffordable to run on a pseudo-global scale until recently and thus their impact in large scale processes is not well known.Aiming to develop the next generation of Met Office weather and climate prediction systems, the UK K-scale project has been established to evaluate the technical challenges, the scientific improvements and the predictability benefits of km-scale models. The first step of the program is the development of a K-scale “model hierarchy”, a family of simulations across several resolutions and two scientific configurations under the same MetOffice Unified Modelling framework (MetUM). Such hierarchy comprises a generic global model at 12km resolution, realizations at different resolutions of the Cyclic Tropical Channel (CTC), which is a global model in the zonal with north and south boundaries at 26N and 44S respectively, and limited area models (LAMS) over several locations at 2.2km. The two scientific configurations are (i) a global-like aimed at global resolutions above 10km, which includes a parametrization of shallow and mid-level convection, and (ii) a regional-like aimed to km- and sub-km-scale LAM which does not parametrize convection at any level.Our results from simulations of the 40-day DYAMOND summer and winter periods show than differences between global-like and regional-like configurations at the same resolution can be as large as differences between models at 12km and 4.4km resolution with the same configuration. When all convective processes are not parametrized in the whole tropics at km-scale resolution, the PDF of precipitation shift towards higher intensities, the diurnal cycle improves in several regions, and the wet and dry biases around the E-W boundaries of LAMs are reduced.The African tropical easterly jet is represented differently across the simulations; with a stronger jet in global-like configurations with convective parametrization. A significant change in mean-state upper wind over the Indian Ocean has potential implications on both subsidence over East Africa, and wind shear over West Africa. These are both tied to widespread rainfall patterns over Africa.Regional-like configurations at km-scale resolution capture the kinetic energy spectra slope -5/3, poorly represented by the global-like model at 12km. The uncertainty growth across the kscale hierarchy is explored with the use of a twin experiment methodology, and in particular the role of equatorial waves in the error growth across resolutions and science configurations.
Unexpectedly small N2O emissions from alpine permafrost rivers on the East Qinghai-Tibet Plateau
Authors: Zhang Liwei , Stanley Emily
Published: March 2024

Streams and rivers emit substantial amounts of nitrous oxide (N2O) and are therefore an essential component of global nitrogen (N) cycle. Permafrost soils store a large reservoir of dormant N that, upon thawing, can enter fluvial networks and partly degrade to N2O, yet the role of waterborne release of N2O in permafrost regions is unclear. Here we report N2O concentrations and fluxes during different seasons between 2016 and 2018 in four watersheds on the East Qinghai-Tibet Plateau. Thawing permafrost soils are known to emit N2O at a high rate, but permafrost rivers draining the East Qinghai-Tibet Plateau behave as unexpectedly minor sources of atmospheric N2O. Such low N2O fluxes are associated with low riverine dissolved inorganic N (DIN) after terrestrial plant uptake, unfavorable conditions for N2O generation via denitrification, and low N2O yield due to a small ratio of nitrite reductase: nitrous oxide reductase in these rivers. We estimate fluvial N2O emissions of 0.432−0.463 Gg N2O-N yr−1 from permafrost landscapes on the entire Qinghai-Tibet Plateau, which is marginal (~0.15%) given their areal contribution to global streams and rivers (0.7%). However, we suggest that these permafrost-affected rivers can shift from minor sources to strong emitters in the warmer future, likely giving rise to the permafrost non-carbon feedback that intensifies warming.
Feeling the rhytm of Nature: challenges and prospects of biodiversity prediction from space
Authors: Rocchini Duccio
Published: March 2024

The assessment of species diversity in relatively large areas has always been a challenging task for ecologists, mainly because of the intrinsic difficulty to judge the completeness of species lists and to undertake sufficient and appropriate sampling. Since the variability of remotely sensed signal is expected to be related to landscape diversity, it could be used as a good proxy of diversity at species level. It has been demonstrated that the relation between species and landscape diversity measured from remotely sensed data varies with scale. In this talk, I aim at providing a theoretical and emipircal background of the mostly used diversity indices stemmed from information theory that are commonly applied to quantify landscape diversity from remotely sensed data.
Dam-break of shear-thickening suspensions: A new perspective for crystal-rich lava flows and lahars -
Authors: Bougouin Alexis , Lhuissier Henri , Forterre Yoel , Metzger Bloen
Published: March 2024

The physical mechanism governing the peculiar behavior of discontinuous shear-thickening suspensions, i.e. a change from liquid-like to solid-like state with increasing applied stress, has recently been described as a frictional transition occuring at the grain scale above a critical shear stress [1, 2, 3]. This understanding offers a new view for describing complex grain-fluid flows, and especially crystal-rich lava flows, which can shear-thicken [4], or lahars, whose heterogeneities affect local friction [5].In this context, we performed macroscopic and local measurements to characterize dam-break laboratory experiments of model shear-thickening suspensions, for which the volume and the solid fraction of the suspension are varied. Below a critical stress related to the gravitational pressure gradient, the suspension flow is close to that of a viscous Newtonian liquid, i.e. strongly decelerating and with a thickness decreasing progressively from the release side to the spreading front [6]. By contrast, above this critical stress, the front velocity becomes constant, i.e. independent of flow height, and the layer thickness is close to be uniform (Figure 1). We interpret this remarquable behavior by the formation of a highly-dissipative (shear-thickened) flow structure at the front, which keeps the suspension upstream essentially stress-free with a low (frictionless) viscosity. We model the front and provide scaling laws for its velocity in good agreement with experimental observations. These results offer a new perspective for the interpretation and modeling of heavily particle-laden geophysical flows, such as crystal-rich lava flows and lahars, which could also be essentially controlled by their highly-dissipative front.1. M. Wyart and M. Cates (2014). Discontinuous shear thickening without inertia in dense non-Brownian suspensions. Phys. Rev. Lett., 112:098302, 2014.2. R. Mari, R. Seto, J. Morris, and M. Denn (2014). Shear thickening, frictionless and frictional rheologies in non-Brownian suspensions. J. Rheol., 58:1693–1724, 2014.3. C. Clavaud, A. Bérut, B. Metzger, and Y. Forterre (2017). Revealing the frictional transition in shear-thickening suspensions. Proc. Natl. Acad. Sci., 114:5147–52, 2017.4. J. V. Smith (1997). Shear thickening dilatancy in crystal-rich flows. J. Volcanol. Geotherm. Res., 79:1-8.5. C. Ancey (2007). Plasticity and geophysical flows : A review. J. Non-Newton. Fluid Mech., 142:4-35.6. H. E. Huppert (1982). The propagation of two-dimensional and axisymmetric viscous gravity currents over a rigid horizontal surface. J. Fluid Mech., 121:43-58.
Landscape response to tectonic deformation and cyclic climate change since ca. 800 ka in the southern Central Andes
Authors: Orr Elizabeth , Schildgen Taylor , Tofelde Stefanie , Wittmann-Oelze Hella
Published: March 2024

Theory suggests that the response time of alluvial-channel systems to perturbations in climate can be related to the magnitude and direction of the forcing, and the length of the system; shorter systems may record a higher frequency of forcing compared to longer systems. The Toro Basin in the Eastern Cordillera of NW Argentina has preserved a suite of eight alluvial-fan deposits along the western flanks of the Sierra de Pascha. Farther downstream, a flight of cut-and-fill terraces have been linked to eccentricity-driven (100-kyr) climate cycles since ca. 500 ka. We applied cosmogenic radionuclide (10Be) exposure dating to the fan surfaces to explore (1) how channel responses to external perturbations may or may not propagate downstream, and (2) the differences in landscape response to forcing frequency as a function of channel length when comparing the upper basin alluvial fan deposits with the lower basin terrace sequence. Our new Toro 10Be dataset consisted of 30 boulder samples from the fan surfaces and five pebble samples from a fan depth profile. We identified two generations of fan surface; the first (G1) and second (G2) generations record surface activity and abandonment between ca. 800 and 500 ka, and within the last 100 kyr, respectively. G1 fans record a prolonged phase of net incision, which has been recognised throughout the Central Andes, and was likely triggered by prolonged and enhanced global glacial cycles following the Mid-Pleistocene Transition. Relative fan surface stability followed, while 100-kyr cut-and-fill cycles recorded by the fluvial terraces persisted downstream, suggesting a disconnect in behaviour between the two reaches. G2 fans record higher frequency climate forcing, possibly the result of precessional forcing of climate (ca. 21/40-kyr timescales). The lack of a high-frequency signal farther downstream provides field support for theoretical predictions of a filtering of high-frequency climate forcing with increasing channel length. We show that multiple climate periodicities can be preserved within the sedimentary record of a single basin. Differences in the timing of alluvial fan and fluvial terrace development in the Toro Basin appear to be associated with how channel length affects fluvial response times to climate forcing as well as local controls on net incision, such as tectonic deformation.
Seismogenic structures and stress state of the Puysegur Subduction Zone (Fiordland, New Zealand) from detailed earthquake observations.
Authors: De Meyer Cédric , Chamberlain Calum J. , Savage Martha K.
Published: March 2024

The formation of new subduction zones, termed Subduction Zone Initiation (SZI), has a large influence on global plate tectonics. However, how stresses within the plate boundary region evolve throughout the evolution of nascent subduction zones remains unresolved. The Puysegur Subduction Zone in Fiordland, near the southern tip of New Zealand’s South Island, is a young, steeply dipping subduction zone and a key site for studying such incipient stages of subduction. Despite the global significance of the Puysegur Subduction Zone, it has received relatively little attention, mostly due to its remote location. Few passive seismic studies have been carried out in the region, and the continuous GeoNet network is too sparse to detect and accurately resolve seismicity around the Puysegur Subduction Zone. Because of this, the present-day structure and stress state of the Puysegur Subduction Zone remain poorly resolved.We aim to study these two unresolved characteristics by using a combination of temporary seismic networks and the permanent GeoNet network to increase station coverage in the region. We have developed a Puysegur-appropriate workflow consisting of automated earthquake detection and association, manual event evaluation and P-wave polarity determination. Highly accurate earthquake locations are obtained using NonLinLoc and a 3D velocity model. Focal mechanism analyses and stress inversion are conducted using Bayesian approaches. Currently, we have obtained a preliminary catalogue for the period between 02/2018 and 10/2018, which shows that the developed methodology is capable of producing more complete earthquake catalogues compared to the national GeoNet catalogue. Preliminary precise hypocentral locations and well- constrained focal mechanisms for moderate-to-large magnitude events are used to constrain the region’s seismogenic structures, such as the subduction interface and major active faults, as well as provide preliminary constraints on the region’s stress state.
The role of plant traits in climate warming responsiveness of tree species
Authors: Ghalayini Yahya , Estrella Nicole , Kattge Jens , Menzel Annette
Published: March 2024

Climate warming is mostly advancing the onset date of spring phenology, yet milder winters with higher temperatures may in fact delay this date, as chilling requirements of species are not fully met in time. The spring phenology of trees and forests is interconnected with ecosystem functions and services, thus the responses of single species to climate warming may have significant implications at the economic and ecological levels. Despite the numerous studies which have been conducted during the past decade on the responses of plant spring phenology to climate warming, the relative importance of various factors, such as phylogeny, floristic status, climate of the native range, life strategy and plant traits, is still not well understood. In this study, twigs from 53 different tree species with two different natural-chilling treatments were forced in climate chambers at 20°C/day and 15°C/night until budburst, and the onset of budburst was monitored 3 times per week. The forcing requirements until budburst were linked to phylogeny (genera), life strategy (pioneer to climax), climate of their native range (oceanic to continental), floristic status (native, ornamental, and invasive) and eight important plant traits from the TRY database. The aim of our study is to answer the following questions: Are pioneer species more responsive to warming compared to later successional strategies? Is the climate of the native range, floristic status and continent of the species related to responsiveness to forcing? Can plant traits indicate the degree of species’ phenological responses to climate warming?
Impacts of biomass burning in Southeast Asia on aerosols over the low-latitude plateau in China: an analysis of a typical pollution event
Authors: Fan Wenxuan , Li Jie , Han Zhiwei , Wu Jian
Published: March 2024

From March to April, widespread forest fires and agro-residue burning frequently occur in Southeast Asia, which release large amounts of gas species and aerosols and impact air quality over the wide source and downwind regions. In this study, we investigated the impact of biomass burning (BB) over Southeast Asia on particulate matter concentrations and aerosol properties in downwind areas of the low-latitude plateau from 1 March to 30 April 2019, with a focus on a typical pollution event in Kunming (KM), the capital of Yunnan Province, by using a wide variety of observations from the Chenggong ground monitoring station in Yunnan University, an air quality network in China, satellite retrievals and ERA-5 reanalysis data and numerical simulation. A regional pollution event contributed by BB pollutants from Southeast Asia and the India-Myanmar trough occurred in Yunnan Province on 31 March to 1 April 2019, which was the only typical pollution event that pollution transmission ran through central Yunnan Province from south to north since 2013, when the Airborne Pollution Action Plan was unveiled by China government. The daily mean PM2.5, PM1, and black carbon concentrations increased by 73.3 μg m−3 (78%), 70.5 μg m−3 (80%), and 7.7 μg m−3 (83%), respectively, and the scattering and absorbing coefficients increased by 471.6 Mm−1 and 63.5 Mm−1 , respectively, at the Chenggong station. The southwest winds exceeding 2 km vertically thick appeared in front of the India-Myanmar trough over the fire regions, pushing BB plumes northward into Yunnan Province. The model results show that 59.5% of PM2.5 mass produced by BB in Yunnan Province was sourced from the Myanmar-Thailand border, and 29.3% was from western Myanmar at a lower altitude (
Prediction of Biodegradation rates of Atmospheric Organics as a function of bacteria diversity using models of different complexity
Authors: Nuñez López Leslie , Amato Pierre , Ervens Barbara
Published: March 2024

Studies of the impacts of bioaerosol on atmospheric processes often focus on their role in ice nucleation, which is largely determined by their physicochemical properties. Living microorganisms may also play roles in chemical processes by interacting with organics and other molecules, in particular in clouds where condensed water promotes metabolic processes.Our previous model studies suggest that such biodegradation by living microorganisms may lead to a significant loss of formic and acetic acids in addition to chemical sinks in the atmospheric multiphase system (Nuñez López et al., 2023).The prior model studies are based on the assumption of a single type of bacteria at fixed number in a small subset of droplets. However, the diversity and abundance of airborne bacteria, and thus their metabolic capabilities, greatly vary with space and time.Explicitly describing multiple types of bacteria in individual droplet classes within cloud models can become computationally expensive and may be unfeasible to implement in larger-scale models aimed at exploring the role of biodegradation as a sink of organics.We present different model approaches of varying complexities to explore the conditions under which simplified expressions for the biodegradation of small organic compounds can be applied. This involves the use of averaged biodegradation rates or proxies for representative bacteria species. Box model simulations are performed for airborne bacterial populations of different diversity and abundance, as observed, e.g. in continental or marine scenarios. Our model studies result in recommendations on how to implement biodegradation into atmospheric models of various scales to account for biological sinks of organic compounds and to ultimately constrain atmospheric organic budgets. Nuñez López, L., Amato, P., and Ervens, B.: Bacteria in clouds biodegrade atmospheric formic and acetic acids, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2023-2270, 2023.
Analysis of the spatial distribution of surface and groundwater abstractions in the territory of Slovakia in the last decade
Authors: Kotrikova Katarina , Lovasova Lubica , Kurejova Stojkovova Michaela , Slivova Valeria
Published: March 2024

In recent years, we have been observing the increasingly frequent impacts of climate change, we are observing a growing number of occurrences of extreme weather events also in Slovakia. Long periods of warm weather without precipitation causing drought are followed by local high-intensity storms that cause extreme flood events. In connection with the solution to the problem of drought monitoring and the setting of drought warnings, documents are analyzed and prepared, which include the water resource balance of Slovakia (one of the basic background materials for water management planning). The water resource balance is based on an assessment of the relationships between water demands and water resources in the past year and assesses when and where water demands are not sufficiently covered.The results of the analysis also include a map image of surface and groundwater abstractions in the territory of Slovakia. The analysis is processed for total and individual abstractions of surface and groundwater, as well as their shares in individual categories of abstractions (waterworks, agriculture, industry, etc.).We present surface and groundwater abstraction averages for the period of the last decade 2013-2022. According to the analysis, over 70% of surface and groundwater abstractions are utilized for public water supply systems, while approximately 20% of these abstractions are used for industrial purposes. 45% of surface water abstractions are used for industrial purposes and 85% of groundwater abstractions are utilized for public water supply systems.In the last year (2022), we can observe an increase of 1.7% in total abstractions compared to the last decade (2013-2022). In the case of surface water abstractions for the year 2022 compared to the period 2013-2022 we can observe a decrease of 3.4% (water supply - an increase of 6.8%, industry – a decrease of 9.2%, agriculture – an increase of 40.7%). In the case of groundwater abstractions for the year 2022 compared to the period 2013-2022 we can observe an increase of 5.4% (water supply - an increase of 8.2%, industry - an increase of 2.4%, agriculture - a decrease of 17.4%).
Information content analysis for aerosol type from a combination of three satellite instruments
Authors: Stöffelmair Ulrike , Popp Thomas , Vountas Marco , Bösch Hartmut
Published: March 2024

Aerosols affect climate in several ways. Their effect depends not only on the aerosol abundance and geospatial distribution but also on the aerosol types present. Therefore, there is an important need for the retrieval of aerosol types from satellite measurements.By combining data from different satellite instruments, information on the composition of aerosols in the atmosphere shall be determined with an optimal estimation retrieval algorithm. We make use of data from three different instruments measuring with different observation characteristics, different spectral ranges (UV, VIS, thermal IR), different viewing geometries (nadir, oblique). The included instruments are dual-view instrument SLSTR (Sea and Land Surface Temperature Radiometer) onboard Sentinel 3A and 3B; and the Infrared Atmospheric Sounding Interferometer (IASI) and the Global Ozone Monitoring Experiment-2 (GOME-2), both onboard Metop A/B/C.In preparation for the information content analysis and future aerosol retrieval, the data from the different instruments are homogenized to a common grid of 40x80 km2, the coarsest instrument resolution (GOME-2), within a temporal matching window of 60 minutes.  A cloud masking algorithm (APOLLO_NG) is then applied to the highest resolution radiometer data (1x1 km2) from SLSTR and in addition to the Advanced Very High Resolution Radiometer (AVHRR) onboard Metop A/B/C to take into account the temporal variation of the clouds.For the information content analysis, a set of those observations is simulated with the SCIATRAN radiative transfer model for different observing conditions / geometries, surface types, aerosol types and aerosol amounts. With these data an analysis of the combined information content is then conducted which focuses on capabilities for the determination of aerosol abundance (total Aerosol Optical Depth - AOD) and aerosol types (as contributions to total AOD of fine / coarse mode, mineral dust, absorbing aerosols) in a cloud-free atmosphere over different ground surface types. The information content analysis will help to identify those instrument channels / spectral windows that carry most of the information which is then used to develop a retrieval algorithm for AOD and aerosol types.
Surge initiation at the terminus of Borebreen (Svalbard): Drivers and impact on calving
Authors: Harcourt William D. , Gajek Wojciech , Pearce Danni , Hann Richard , Luckman Adrian , Rea Brice R. , Benn Douglas I. , James Mike R. , Spagnolo Matteo , Nanni Ugo
Published: March 2024

Approximately 21% of Svalbard’s glaciers are classified as surge-type and undergo cyclical changes in ice velocity between quiescent (slow) and active (fast) phases. Whilst it is generally understood that processes at the glacier bed drive surge initiation, the physical mechanisms translating basal sliding to ice flow variability and cyclicity remain open questions. Recent mapping of glacier velocities across Svalbard has identified an acceleration in ice flow at the Borebreen tidewater glacier which terminates on the northwestern side of Isfjorden. Before 2018, average summer velocities at Borebreen were ~0.6 m/d but more than doubled to 2.4 m/d by 2023. Borebreen last surged ~100 years ago, hence the acceleration in ice velocity suggests it is the result of the glacier transitioning to an active surge. In this contribution, we will discuss results from a summer field campaign to Borebreen in August 2023. Using a multi-sensor network of seismic arrays, Terrestrial Laser Scanners (TLS), and drones, we characterise present day surge dynamics and use the data to understand the drivers. In addition, optical imagery from the PlanetScope constellation and Synthetic Aperture Radar (SAR) data from Sentinel-1 are used to determine surface conditions (e.g. surface melt patterns, crevasses, proglacial turbid plumes) and quantify ice velocities. Here, we will report on the following: 1) basal processes (e.g. stick-slip events, icequakes) under Borebreen; 2) calving processes at the over-steepened ice cliff of the surge front; 3) ice velocity extracted from drone photogrammetry, Planetscope imagery and Sentinel-1 SAR scenes; and 4) surface conditions (e.g. crevassing, surface melt) over the course of the ablation season and its relationship with ice dynamics. We find that the surge initiated at the glacier terminus and has been propagating upglacier. The glacier speed doubles each spring in response to elevated air temperatures which leads to surface melting and the delivery of meltwater to the glacier bed. Furthermore, we identify clusters of seismicity at the glacier bed, far from the terminus, which appear to indicate sliding. Our results push forward our understanding of the processes that initiate and sustain glacier surges and glacier instabilities in general.
Radar cluttering incidence in the estimation of rainfall fields in the Colombian Andes
Authors: Ramírez Tamayo Jorge Iván , Piña Fulano Adriana Patricia , Ladino Rincon Alfonso
Published: March 2024

The spatial variability of rainfall is difficult to measure due to the lack of ground weather rain gauges. As a result, meteorological radars have become crucial sources of information for estimating precipitation fields. However, radar cluttering, which refers to external factors of nature that affect radar data quality, poses a significant challenge, and contributes to errors and uncertainties in the estimation process. In this study, we focused on analyzing the impact of cluttering on the Barrancabermeja C-band weather radar, situated between the Eastern and Central Ranges in the Colombian Andes. The analysis was conducted using radar information collected between 2019 and 2020. A frequency analysis of reflectivity of rainless day records showed the topographic interferences caused by the surrounding radar Ranges. Afterwards, the radar quality index (RQI) for both rainy and dry conditions was estimated considering factors such as clutter frequency map, partial beam blockage, effects of range distance quality, radar noise, and attenuation. The evaluation revealed an approximate clutter area of 50% in a beam elevation of 0.5°, primarily associated with the topographical interferences, indicating a direct impact of the Andean region on radar data quality.Finally, we focused on intense rainfall events (greater than 10mm per event) to determine the parameters of three Quantitative Precipitation Estimation (QPE) relationships (Marshall & Palmer (1948), Seliga & Bringi (1976), and Sachidananda & Zrinc (1987) methodologies). Records from 91 available rain gauges were used to obtain relationships for individual gauges and, for four individual rings spaced 50 km from the radar. By employing these relationships, we calculated uncertainty maps of the quantitative precipitation estimation, obtaining an uncertainty of 60% from cluttering in the QPE of the meteorological radar. Overall, our findings emphasize the significant role of cluttering in the estimation of precipitation fields from the Barrancabermeja radar. The study underscores the importance of addressing cluttering effects and accounting for the topographical interferences in radar data interpretation to enhance the accuracy of quantitative precipitation estimates in the Andean region.
Variation among desert shrub patches in evapotranspiration
Authors: Wang Xinping
Published: March 2024

A major concern for revegetated desert ecosystem is accounting for the evapotranspiration dynamics which is influenced by the carrying capacity of the soil moisture content. Most field observations indicate that soil moisture at certain depth varies with the stochastically occurrence of rainfall events, and the evapotranspiration at community level also varies with the total of annual precipitation. Based on a study of the long-term field observation on the revegetated desert ecosystem, we find that the evapotranspiration of the shrub community correlates closely to the availability of soil moisture, and it can be quantified by analytical description of the stationary and transient joint behavior of plant evapotranspiration and soil moisture. The experimental results indicate that the size and diversity of plant species in water-limited ecosystem can be determined by plant evapotranspiration, which is a comprehensive indicator for plant water resource competition. These results suggest that revegetating large sandy areas with desert shrubs could reduce soil water storage by transpiration, which could significantly change groundwater recharge conditions. However, from a viewpoint of desert ecosystem reconstruction, it appears that natural rainfall can sustain desert shrubs which would reduce erosion loss of sand.
Improving Estimates of Arctic Ocean CO2 Uptake
Authors: Dutch Victoria , Bakker Dorothee , Landschützer Peter , Roobaert Alizée , Kaiser Jan
Published: March 2024

The Arctic Ocean covers only 3 % of the Earth’s surface but contributes 5 - 14 % of the global ocean carbon sink. Sparse and unevenly distributed observations of the partial pressure of CO2 (pCO2) hinder our understanding of the magnitude and the controlling mechanisms of this carbon sink. In order to constrain the magnitude of this flux, we adapt the Self-Organising Map – Feed-Forward neural Network (SOM-FFN) method of Landschützer et al. (2016) to interpolate existing observations and construct a monthly 1 x 1 degree pCO2 product for the Arctic Ocean from 1991 - 2022. We first divide the Arctic Ocean (i.e., the region ≥ 55° N) into five biogeochemical provinces; four obtained from using the SOM method and a fifth for all grid cells with greater than 85 % ice cover. For each province, we then derive non-linear relationships between pCO₂ and predictor variables (i.e., biogeochemical drivers) using the FFN method. The monthly reconstructed Arctic pCO2 product is then evaluated against existing observations of surface ocean pCO2, chiefly from SOCATv2023 and from independent timeseries stations. Our study shows that biogeochemical properties previously selected as predictor variables at the global scale are not well suited to the Arctic Ocean. Limiting the spatial domain from which relationships are derived also improves performance, with less biased p(CO2) values predicted when excluding the Baltic Sea. 
Objective Identification of Tropical Cyclones with Severe Storm Surge Potential for the North-west Pacific
Authors: Zhang Xiaoqi , Leckebusch Gregor C , Ng Kelvin S
Published: March 2024

Storm surges caused by tropical cyclones can significantly impact on coastal areas in East Asia, including megacities e.g., in China. To inform effective adaptation and mitigation planning, a robust storm surge hazard assessment is essential. Unfortunately, the real frequency-intensity distribution of relevant storm-surge levels can only be estimated with large uncertainly based on limited historical observations.This study demonstrates the successful development of a two-step, objective and automated identification and selection approach of storm-surge relevant TCs for large model data sets where no ground truth verification is possible. In our approach, we combine for the first time two established identification and tracking tools originally developed for extra-tropical cyclones and storms and apply these to identify tropical cyclones. In the first step, we adapted the widely used Murray & Simmonds (1991) University of Melbourne tracking scheme (MS-Track) to the specific conditions of TC tracking in the North-west Pacific. In the second step, we apply the windstorm tracking tool WiTRACK to TC-induced severe wind fields to provide and attach the potential storm-surge relevant information in addition to just the core track provided by the MS-Track.By validating our results with ERA5 reanalysis data and IBTrACS, we show that our method is simple yet has a well comparable performance in detecting and assessing relevant TC events than more complex tracking approaches. Based on this performance this approach is well-designed and specifically intended to specific applications in CAT modelling approaches, e.g. for the creation of physically consistent event sets for storm surges.
Modeling soft X-ray emissions at the dayside magnetopause
Authors: Xu Qiuyu , Koutroumpa Dimitra , Modolo Ronan , Sun Tianran , Connor Hyunju , Sembay Steve
Published: March 2024

In this study, we simulate the Solar Wind Charge Exchange (SWCX) soft X-ray emissions at dayside magnetopause by using magnetohydrodynamic (MHD) and Test-Particle (TP) models. Due to the single fluid description, the MHD model is unable to resolve the particle kinetic effects or distinguish the magnetospheric plasma and the solar wind plasma. We investigate these effects with the TP model. As the TP model does not self-compute magnetic and electric field, the magnetic and electric field data obtained from OpenGGCM and PPMLR MHD model are used as the input to TP model. The soft X-ray emissivity maps simulated from pure OpenGGCM and PPMLR MHD approaches and from TP-OpenGGCM and TP-PPMLR MHD approaches are presented and compared. The results indicate that the TP model can well resolve the kinetic effects and the individual spectral characteristics, and it does not require a masking method in the magnetosphere. Therefore the TP model is a complementary approach for simulating the X-ray emissions in the dayside magnetosheath and cusps.
Earthquake source characterization in stable continental regions: Application to the Armorican Massif, France
Authors: Alloncle Marion , Mocquet Antoine , Bonnin Mickaël
Published: March 2024

The seismic moment M0, the associated moment magnitude Mw, and the corner frequency fc are essential parameters for earthquake studies and seismic risk management. In the context of stable continental regions (SCRs), remote from active plate boundaries, the assessment of these parameters is made difficult by the low energy release associated with each earthquake and the low density of seismological networks.In the north west of France, the Armorican Massif and its surroundings are part of a SCR, where the densification of the seismological network, completed in 2019, now allows for a reassessment of the regional seismicity. Though characterized by very small strain rates, the region currently displays a high rate of low-to-moderate earthquakes (up to a few Mw lower or equal to 4.0 – 5.0). For such small earthquakes, these assessments are particularly sensitive to the signal-to-noise ratio, to the seismic structure of the region, to its attenuation properties, and to the azimuthal distribution of the regional network with respect to the focal mechanisms.We attempt to determine the M0, and the fc, of 106 earthquakes, detected in northwestern France between 2015 and 2023, with local magnitudes ML ranging from 2.0 to 5.3, using spectral methods. We obtained a linear relationship between ML and Mw for Mw ranging from 1.5 to 5.0. Our analysis also highlighted the importance of the frequency dependence of attenuation on the assessment of the fc. This study will show the relation between M0 and fc in the region.
Small, flashy catchments response to variation in rainfall profile shape
Authors: Seawell Alexandra
Published: March 2024

Flash flooding has the potential for severe consequences but is much less well understood or predictable than longer duration flooding. It is important to improve understanding of patterns of rainfall and behaviour of responding catchments in order to manage flash flooding effectively. One aspect of rainfall that could potentially affect flood hydrographs is the temporal shape of rainfall profiles.Design flood estimation in the UK is principally based on the FSR /FEH/ReFH methodology, which uses a symmetrical centre-loaded profile for rainfall. However, recent research undertaken during Roberto Villalobos Herrera’s PhD is that front-loaded and back-loaded rainstorms occur just as frequently as centre-loaded. My PhD seeks to test how different rain profile shapes change the river flow hydrograph and flooding across the catchment.My PhD concentrates on small catchments which have typically been less studied and because they are likely to be responsive to short, intense rainfall that can cause flash flooding. Hydrological modelling has been undertaken for 24 identified study catchments using ReFH2.3 software, which is the standard flood estimation design software in the UK. Results indicate that use of symmetrical profiles risks underestimating potential flood peaks compared to back-loaded storms. Meanwhile, time-to-peak is typically shorter for frontloaded storms indicating the hydrograph rises faster, but lagtime is shorter for back-loaded storms indicating the peak flow occurs more quickly after the peak rain. As well as modelled responses, I have also begun identifying and analysing observed hydrographs for selected study catchments to see if these show any pattern in their response to rainfall profile shapes.