bluuebunny/crossref_metadata_2025 huggingface dataset:
Assessing the calibration of multivariate ensemble forecasts: E-values and the choice of pre-rank function
Authors: Allen Sam , Ziegel Johanna
Published: February 2023

It is often stated that the goal of probabilistic forecasting is to issue predictive distributions that are as sharp as possible, subject to being calibrated. To assess the calibration of ensemble forecasts, it is customary to employ rank histograms. Rank histograms not only assess whether or not an ensemble prediction system is calibrated, but they also reveal what (if any) systematic biases are present in the forecasts. This information can readily be relayed back to forecasters, helping to improve future predictions. Such is the utility of rank histograms, several extensions have been proposed to evaluate the calibration of probabilistic forecasts for multivariate outcomes. These extensions typically introduce a so-called pre-rank function that condenses the multivariate forecasts and observations into univariate objects, from which a standard rank histogram can be constructed. Several different approaches to construct multivariate rank histograms have been proposed, each of which differs in the choice of pre-rank function. Existing pre-rank functions typically aim to preserve as much information as possible when condensing the multivariate forecasts and observations into univariate objects. Although this is sensible when testing for multivariate calibration, the resulting rank histograms are often difficult to interpret, and are therefore rarely used in practice.         We argue that the principal utility of these histogram-based diagnostic tools is that they provide forecasters with additional information regarding the deficiencies that exist in their forecasts, in turn allowing them to address these shortcomings more readily; interpretation is therefore a key requirement. We demonstrate that there are very few restrictions on the choice of pre-rank function when constructing multivariate rank histograms, meaning forecasters need not restrict themselves to the few proposed already, but can instead choose a pre-rank function on a case-by-case basis, depending on what information they want to extract from their forecasts. We illustrate this by introducing a range of possible pre-rank functions when assessing the calibration of probabilistic spatial field forecasts. The pre-rank functions that we introduce are easy to interpret, easy to implement, and they provide complementary information. Several pre-rank functions can therefore be employed to achieve a more complete understanding of the multivariate forecast performance. Finally, having chosen suitable pre-rank functions, tests for univariate calibration based on rank histograms can readily be applied to the multivariate rank histograms. We illustrate this here using e-values, which provide a theoretically attractive way to sequentially test for the calibration of probabilistic forecasts.
Comprehensive dataset assessing extreme winds over Europe in Regional Climate Models
Authors: Outten Stephen , Sobolowski Stefan
Published: February 2023

Extreme events cause vast amounts of damage across Europe every year, with heavy rainfall events often causing the greatest loss of life and extreme wind events often causing the greatest financial losses. The accurate projection of the changes in extreme winds will continues to be invaluable for many industries, including insurance, construction, energy, and afforestation. Adaptation planning requires the estimation of how the magnitude and frequency of extreme events, including extreme winds, will vary in the future.Extreme winds were examined in a selection of 15 Euro-CORDEX simulations. The peaks-over-threshold approach was used identify the extreme events based on the fitted Generalized Pareto Distributions (GPD), and maps of 30-year return winds for all locations over Europe were derived. Future changes in the frequency of extreme winds were assessed for Northern, Central, and Sothern Europe for three future periods, being the near, mid, and end of this century. The results show that the frequency of extreme wind events will increase from one period to the next over the 21st century in all three regions of Europe.Recently, a new dataset has been created by extending the analysis to 52 of the Euro-CORDEX simulations, each a unique combination of global and regional model, using both the peaks-over-threshold and annual maxima methods. Since these simulations include multiple downscalings of the same global climate models by different regional climate models, it is possible to intercompare how the different model combinations represent extreme winds. This allowed us to isolate the influence of individual global and regional models in shaping the extreme winds in Euro-CORDEX simulations. From this, we have been able to statistically create maps of extreme winds across Europe for GCM-RCM combinations that were never run. These results will be presented, along with details of the new dataset, and a summary of the original 15-member study.
Changes in Cs-137 concentrations in river-bottom sediments and their factors in Fukushima Prefecture rivers
Authors: Wada Naoyuki , Onda Yuichi , Gao Xiang , Tang Chen
Published: February 2023

The Fukushima Daiichi Nuclear Power Plant accident (FDNPP) in 2011 resulted in the release of large amounts of Cs-137 into the atmosphere. Cs-137 deposited on land was mainly distributed in forests, but some of it has been discharged to the sea through rivers. The dissolved and suspended forms of Cs-137 in rivers have been focused on, and it is known that the discharge mechanism and concentration formation of Cs-137 differ depending on the land use in the river basin. On the other hand, there are few cases that focus on the dynamics of Cs-137 in river bottom sediments. River-bottom sediment is less likely to flow downstream than suspended sediments, so contamination in the downstream area may be long-term.We will clarify the migration mechanism of Cs-137 in rivers including river-bottom sediment.Therefore, we will analyze data collected from 2011 to 2018 in 89 watersheds in Fukushima prefecture. In analyzing the data, we removed sampling points with brackish water using electrical conductivity and corrected for particle size to standardize the surface area of particles that absorb Cs-137.As a result, it was found that unlike dissolved and suspended forms, the Cs concentration in river-bottom sediments can increase within the initial year. This is related to the average initial deposition in the watershed and the amount of initial deposition at the river-bottom sediment sampling sites, with a tendency to increase with relatively higher initial deposition in the upstream area. It was also known that the decrease in suspended Cs concentration was more pronounced when anthropogenic activities in the watershed were more active, but there was no clear relationship between land use in the watershed and changes in river-bottom sediment Cs concentration. This indicates that suspended sediment Cs concentrations are controlled by initial deposition to suspended sediment production sources, whereas river-bottom Cs concentrations are controlled by multiple factors such as sediment traction and Cs supply from river water.
Web-ASsisted Method for NetCDF4 Climate Data Visualization (WASM4NC)
Authors: Cayoglu Ugur
Published: February 2023

The goal of this project is to enable earth system scientists to visualize (un)structured NetCDF4 data on a 3D globe locally with just the browser. The provided solution will work on any client device incl. mobile phones, tablets, TVs and laptops. The user will be able to drag & drop a NetCDF4 file onto the browser, visualize the content of the file on a globe and interact with the data e.g. switch between altitudes, timestamps and projections. Further, all data will be kept at client side and no data transfer will occur.The problem being addressed by this project is fast visualization of climate data. Currently, there is no hassle-free way to visualize the content of a climate dataset for researchers and stakeholders. Either an application needs to be downloaded (like Panoply) or the necessary NetCDF drivers (e.g. C, C++ or Python) and visualization libraries (e.g. cartopy) need to be installed. Further, none of the solutions work across devices like mobile phones, tablets, TVs or laptops. The heterogeneity of the solution space increases further, if we want 3D visualizations and easy user experience for public outreach projects. The main stakeholders will be earth system scientists, with data curators, outreach experts, and decision makers being additional beneficiaries. The scientists will be able to instantly visualize their data on any device in 3D and interact with it. Data curators can gather information about the contents of the data at a glance. Outreach experts can show potential hazards and developments across the earth in 3D an easily understandable way. Decision makers can view hazards and their consequences at a first glance.
In situ VOC measurements in the center of Paris under local biogenic influence ( Spring- Summer 2022)
Authors: Kalalian Carmen , Gros Valérie , Simon Leïla , Douet Vincent , Faucheux Aurélien , Boitel Christophe , Bocquet Nathalie , Kammer Julien , D'anna Barbara , Petit Jean-Eudes , Favez Olivier , Leymarie Juliette , Boissard Christophe
Published: February 2023

It is generally acknowledged that urban vegetation improves the environmental quality of cities around the world as they can provide ecosystem services like mitigation of urban heat island effect, and capture of atmospheric pollutants by the leaf surfaces. However, vegetation is also a source of Biogenic Volatile Organic Compounds (BVOC), that can be targets of oxidants produced from chemical interactions with anthropogenic atmospheric pollutants. Such oxidation phenomena trigger the formation of secondary pollutants like ozone (O3) and secondary organic aerosols (SOA). As part of the sTREEt (Impact of sTress on uRban trEEs and on city air quality) project, the present work aims to (i) characterize the ambient gaseous composition in the center of Paris (Town Hall) impacted by a local biogenic source (an urban garden and street trees) and subjected to significant anthropogenic contributions (mainly traffic), and (ii) estimate the contribution of BVOC (vs Anthropogenic VOC) and ultimately their impact on the ambient air quality (O3, SOA). A field campaign took place in Paris city center, from June 8th to July 6th, 2022, notably including a heat wave period on June 17th and 18th (with temperature up to 37°C). The experimental set-up comprised continuous measurements of VOC (using PTR-ToF-MS), NOx (as traffic tracer), aerosol chemical composition (using ACSM) and meteorological parameters (i.e., temperature, wind, light irradiation). VOCs speciation (including terpenes) was also performed off-line based on cartridges analyses for selected days. Results are presented and compared here with measurements at a suburban site at the SIRTA-ACTRIS facility (20 km SW of Paris).
The overall VOC concentrations at the town hall site were higher than at the SIRTA site. Furthermore, isoprene and monoterpenes were mainly of anthropogenic origin, with a diurnal variability and a strong correlation with traffic markers (NOx and aromatic VOC). However, during the heat wave, the concentrations of isoprene and monoterpenes increased and showed a different variability than that of the traffic markers. The concentration of isoprene became very significant with levels around 6 ppb (comparable to the SIRTA site), due to the increase in the biotic component, which may promote the formation of ozone. On the other hand, the moderate increase in monoterpene concentrations (0.1 to 0.7 ppb), due as well to the increase in the biotic component, could contribute significantly to the SOA formation. Thus, assuming a near future increase in the frequency and intensity of heat waves, the contribution of the biogenic source to the ambient air quality may be even more important in urban areas with strong anthropogenic contributions.
Antarctic ice sheet response to AMOC shutdowns during the penultimate deglaciation
Authors: Menthon Maxence , Bakker Pepijn , Quiquet Aurélien , Roche Didier M.
Published: February 2023

According to geological records, the sea level during the Last Interglacial (∼ 129–116 ka) peaked 6 to 9 m higher than during the pre-industrial with a major contribution from the Antarctic ice sheet (Dutton et al. 2015). According to Clark et al. 2020, a longer period of reduced Atlantic Meridional Overturning Circulation (AMOC) during the penultimate deglaciation compared to the last deglaciation could have led to greater subsurface warming and subsequent larger Antarctic Ice Sheet retreat.Here we study the response of the Antarctic ice sheet to climate forcing with a forced AMOC shutdown at different timing and duration during the penultimate deglaciation (∼ 138–128 ka). The simulations are done with the Earth System Model of Intermediate Complexity iLOVECLIM (Roche et al. 2014) and the ice sheet model GRISLI (Quiquet et al. 2018), using the recently implemented sub-shelf melt module PICO (Reese et al. 2018). In the present simulations the GRISLI is forced with the iLOVECLIM simulations and is a step towards a fully coupled climate - ice sheet set up to take into account the climate - ice sheet interactions in a physical way.We hypothesize that both the duration and timing of reduced AMOC can significantly affect the sensitivity of the Antarctic Ice Sheet. A longer period of AMOC reduction will lead to a larger subsurface warming in the Southern Ocean and subsequently a larger ice sheet retreat. On the other hand, an AMOC reduction earlier (later) in the deglaciation implies that the ice sheet that is affected by this subsurface warming is still fairly large (already small). We will discuss both the individual as well as combined effect of duration and timing on the ice sheet evolution.
Expansion and Contraction of the Auroral Oval Area
Authors: Ohma Anders , Laundal Karl Magnus , Reistad Jone Peter , Hatch Spencer Mark , Madelaire Michael , Gasparini Sara , Decotte Margot , Walker Simon James
Published: February 2023

The aurora is a visible manifestation of Earth’s coupling to near-Earth space. The emitted light is produced by charged particles that precipitate into the upper atmosphere. These particles are usually located on closed magnetic field lines that connect directly between the northern and southern hemisphere. As a result, Earth’s aurora often appears in an oval shape surrounding the magnetic pole. Inside the oval, at high magnetic latitudes, is a region with open magnetic field lines that extend into the solar wind. This region of open magnetic flux is the polar cap and is a consequence of the Dungey cycle: Reconnection between the solar wind magnetic field and closed terrestrial field lines at the dayside magnetopause produces open field lines which are transported to the nightside where they are again closed by reconnection. A fundamental property of the magnetosphere-ionosphere system is that changes in the amount of open magnetic flux is equal to the net difference between the dayside and nightside reconnection rates. That is, the polar cap expands when dayside reconnection dominates and contracts when nightside reconnection dominates. This is known as the expanding/contracting polar cap paradigm, and has been studied extensively in the last few decades. The expansion and contraction of the aurora itself has received less attention. In this work, we use global auroral images to study the spatiotemporal evolution of the auroral oval. We investigate how the solar wind, open flux and auroral flux covary. Furthermore, we attempt to determine how well a pure fluid description of the auroral zone can explain the observed evolution.
Beyond single tree mortality: understanding biomass allocation and turnover of twigs and branches in forest FACE experiments
Authors: van Wijngaarden Klaske , Smith Benjamin , Medlyn Belinda , Larsen Joshua , Pugh Thomas
Published: February 2023

Rising carbon dioxide (CO2) levels can lead to more carbon sequestration in plant biomass, and forests’ natural ability to store carbonin long-lived woody tissue is of particular interest. However, the extent of CO2-fertilization in trees varies across age, species and the availability of other resources. Woody tissue encompasses more than just the tree’s trunk, and a critical knowledge gap lies in the allocation of carbon to the other woody components like branches and twigs. In addition, the flux of woody carbon from the tree to the forest floor (turnover) is more than events of single tree mortality. These fluxes come in the form of litterfall, breakage of whole branches or complete tree mortality. The goal of this study is to quantify biomass allocation patterns and subsequent turnover rates within the woody carbon pool of two contrasting forest FACE experiments, BIFoR FACE in Staffordshire UK, and EucFACE in Sydney, Australia and answer the following questions: how do these allocation patterns determine the potential for carbon sequestration and how do patterns shift with elevated CO2 concentrations?Terrestrial laser scanning provided the tools to determine canopy structure on a stand scale, and the use of algorithms on the resulting point cloud trees supplied data on the partitioning of biomass among twigs, branches and stems. These results were then used to test general hypotheses about canopy structure and how it changes with elevated CO2. The fluxes from the different wood components were quantified with monthly observations and collections, litter traps to collect the smallest material and transects to make an inventory of larger compartments like branches. The results of these studies will be combined with the canopy structure partitioning fractions to determine if the allocation patterns vary over time and between two contrasting forest types. It is worthwhile to increase our understanding of the dynamics of all woody components within forests and on a global scale beyond single tree mortality to improve the accuracy of predictive carbon budget models.
Objectively Determining the Number of Similar Hydrographic Clusters with Unsupervised Machine Learning
Authors: Trahms Carola , Wölker Yannick , Biastoch Arne
Published: February 2023

Determining the number of existing water masses and defining their boundaries is subject to ongoing discussion in physical oceanography. Traditionally, water masses are defined manually by experts setting constraints based on experience and previous knowledge about the hydrographic properties describing them. In recent years, clustering, an unsupervised machine learning approach, has been introduced as a tool to determine clusters, i.e., volumes, with similar hydrographic properties without explicitly defining their hydrographic constraints. However, the exact number of clusters to be looked for is set manually by an expert up until now. We propose a method that determines a fitting number of clusters for hydrographic clusters in a data driven way. In a first step, the method averages the data in different-sized slices along the time or depth axis as the structure of the hydrographic space changes strongly either in time or depth. Then the method applies clustering algorithms on the averaged data and calculates off-the-shelf evaluation scores (Davies-Bouldin, Calinski-Harabasz, Silhouette Coefficient) for several predefined numbers of clusters. In the last step, the optimal number of clusters is determined by analyzing the cluster evaluation scores across different numbers of clusters for optima or relevant changes in trend. For validation we applied this method to the output for the subpolar North Atlantic between 1993 and 1997 of the high-resolution Atlantic Ocean model VIKING20X, in direct exchange with domain experts to discuss the resulting clusters. Due to the change from strong to weak deep convection in these years, the hydrographic properties vary strongly in the time and depth dimension, providing a specific challenge to our methodology. Our findings suggest that it is possible to identify an optimal number of clusters using the off-the-shelf cluster evaluation scores that catch the underlying structure of the hydrographic space. The optimal number of clusters identified by our data-driven method agrees with the optimal number of clusters found by expert interviews. These findings contribute to aiding and objectifying water mass definitions across multiple expert decisions, and demonstrate the benefit of introducing data science methods to analyses in physical oceanography.
Numerically modelling along-strike rheologic variations in 3D subduction zones
Authors: Neuharth Derek , Behr Whitney , Holt Adam
Published: February 2023

Because subduction zones can extend thousands of kilometers along-strike, many previous studies have used 2D subduction models which inherently assume homogeneity along-strike. However, in nature we see that subduction zones are often heterogeneous along-strike and can exhibit significant variations in the subducting plate age, thickness, and viscosity, trench location, as well as in the geometry of the overriding plate. While 2D models can test large system-wide changes to these parameters by assuming homogeneity along-strike, how variabilities in the geometry and rheology interact with each other in a three-dimensional setting is poorly understood.To understand how along-strike variations affect an evolving subduction zone, we developed self-consistent 3D subduction models using the finite element code ASPECT. The models include a thermally-defined subducting plate and overriding plate, and a constant-viscosity crust/interface. We vary two primary parameters along-strike: 1) the viscosity of the interface shear zone and 2) the thickness of the overriding plate, which affects the interface shear zone length. We explore how varying each of these parameters affects the subduction, convergence, and trench rollback velocities, slab morphology, and the stress distribution and topography formation within the overriding plate.We find that along-strike variations to the interface viscosity or overriding plate thickness has only minor effects on the slab morphology and convergence velocities, but largely affects the surface stress distribution. While variations in the overriding plate thickness or interface viscosity do not affect the convergence velocity along-strike, having a thicker overriding plate or stronger interface leads to a reduction in the system-wide convergence velocity. Despite the similar velocities along-strike, slab morphology changes along-strike, with lower dips seen in regions with a greater overriding plate thickness or weaker interface viscosity. Most importantly, along-strike changes to either parameter results in significant differences in the surface stress distribution. Higher stresses build within the side that has a thicker overriding plate or stronger interface. This increase in stresses results in greater topography, with a maximum variation along-strike of up to ~1.2 km.
Calibration and field validation of smart soil moisture monitoring system
Authors: Yousafzai Hammad Ullah Khan , Jadoon Khan Zaib , Ali Muhammad Zeeshan
Published: February 2023

Agriculture is one of the crucial sectors of Pakistan’s economy – accounting for about 21% of GDP and engaging approximately 50% of work force and is the major source of livelihood of a substantial segment (67%) of population. Traditionally farmers use the classical methods for irrigation like flood irrigation, border irrigation, and furrow bed irrigation, which are less efficient and cause more water losses due to surface runoff and infiltration of water beyond the root zone of the crop. Furthermore, excessive pumping of water from the wells caused high consumption of energy. Due to lack of proper monitoring system for irrigation water management, farmers use more water than required water to the crop. High rate of water losses in irrigation systems is due to heterogeneity of soil in the agricultural field and water infiltration beyond the root zone of the crop.This paper presents the calibration and field validation of soil moisture sensors for smart irrigation system using IoT (Internet of Things). Field soil samples were collected to calibrate soil moisture sensors. Different amount of water was added to oven-dried soil samples to create soil moisture variability and the voltage values of the capacitive soil moisture sensor were measured to establish a calibration curve. After the calibration of sensors, an array of soil moisture sensors was installed vertically to monitor soil moisture dynamics within the root zone of the crop. The Wi-Fi/LORA module is used to transfer the data to a cloud server at a frequency of 60sec/cycle. The data from the cloud server can be accessed via the mobile phone application “BLYNK”. Results show that the vertical dynamics of soil moisture were clearly measured by the smart soil moisture monitoring system at different depths. The calibrated sensors can be used for smart irrigation systems and can be easily adapted for different irrigation methods.
Water-rock interaction processes in springs and wells of the Mexico City groundwater flow system
Authors: Olea Olea Selene , Gómez Reyes Eugenio , Escolero Oscar , Armas Vargas Felipe de Jesús
Published: February 2023

The Mexico City region is a densely populated region in the world and has problems in guaranteeing the supply of drinking water to its inhabitants. Its groundwater flow system is subject to intensive exploitation. The water in the city is coming from a lot of sources as wells located in the city and springs in the ranges. The geology in the basin is mainly in lacustrine sediments; volcanic rocks shallow and deep and carbonate rocks in the depths.We collected water table values, major ions, and trace elements compositions from other research: wells (1999) and springs (2015) to investigate hydrogeochemical processes as well as to understand the hydrodynamics of groundwater and their chemical differences between ranges and plains. The groundwater chemical composition is related to the water-rock interaction processes.We applied two inverse model sections (PHREEQC code) in springs and wells. The inverse model section in the springs showed the dissolution of gypsum, biotite, SiO2 (aqueous), volcanic glass, labradorite, chloride, and precipitation of amphibole, kaolinite, and H2O (gaseous). Whereas the inverse section model in wells presents the dissolution of CO2 (gaseous), gypsum, biotite, volcanic glass, halite, plagioclase, olivine, and precipitation of kaolinite and pyroxene.Understanding the hydrochemical mechanisms of water-rock interactions eventually leads to the development of appropriate strategies for sustainable groundwater management.
Assessment of the impact of the Italian National Forest Strategy on carbon sequestration in the Lazio region up to 203
Authors: Tarasova Ekaterina , Chiriacò Maria Vincenza , Perugini Lucia
Published: February 2023

The sustainable policies and practices such as agricultural, forestry and land management are crucial for ensuring the long-term provision of ecosystem services. According to the European Green Deal strategy, at least 3 billion more trees should be planted in the European Union by 2030. In support of this target, the Italian National Forest Strategy proposes actions aimed at reforestation, afforestation and agroforestry. Enhancing forest density and cover enhances the capacity to remove CO2 and store it as organic carbon in the global terrestrial biosphere. Spatial decision support tools can support policy makers in addressing these challenges and relevant assessment of land-based mitigation options to reduce emissions in the land sector. Despite the specific goal set in the European Green Deal strategy, there is still no clear understanding of which territory in Italy will be involved in the planned actions. Therefore, there is a need to build suitability maps to determine the future change of the land cover in connection with the European strategies and planned actions up to 2030. This study suggests not only possible future land cover maps for the Lazio region, compiled in accordance with the land use policy, but also an assessment of the planned carbon sequestration based on the proposed maps.
The role of electrons and helium atoms in global modeling of the heliosphere
Authors: Fraternale Federico , Pogorelov Nikolai V. , Bera Ratan K.
Published: February 2023

In situ and remote observations of the outer regions of the heliosphere and in the local interstellar medium (LISM) by Voyager, New Horizons, and IBEX continue to present new challenging questions, reflecting the complex processes of the solar wind (SW) - local interstellar medium (LISM) interaction. We present a new version of our recent 3-D MHD-plasma/kinetic-neutrals model of the SW-LISM interaction, which self-consistently includes neutral hydrogen and helium atoms. The new model treats electrons as a separate fluid assumed to co-move with the plasma mixture. In addition, it includes the effect of Coulomb collisions between electrons, He+ ions, and protons. The properties of electrons in the distant SW and in the very local interstellar medium (VLISM) are mostly unknown due to the lack of in situ observations. In this study we discuss the implications of using different models for the electron pressure. A common assumption (model 0) in single-ion global models is to assume that electrons have the pressure of the ion mixture. In this case electrons become hot in the distant SW where plasma is energetically dominated by pickup ions. In the proposed new model, electrons in the SW are colder, which leads to a better agreement with New Horizons observations in the supersonic SW. In the VLISM, however, ions and electrons may be almost in thermal equilibrium due to Coulomb collisions. As far as the plasma mixture properties are concerned, the major differences between the models are in the inner heliosheath, where colder electrons result in hotter protons and induce cooling of the plasma mixture due to the increase in the charge exchange frequency. This makes the heliosheath thinner by ~5 AU along the upstream direction and up to 60 AU in the downwind region. The filtration of interstellar H and He atoms is also discussed. At 1 AU, in the model with separate electrons the H density increases by ~2%. However, the fraction of pristine H atoms decreases by ~12%, while that of atoms born in the IHS increases up to ~35%. While the density of He atoms in the SW remains essentially unchanged, the contribution from the warm breeze increases by ~3%.
Exceptionally preserved neotectonic fault scarps in SW Namibia record large-magnitude structurally-controlled SCR paleoseismicity
Authors: Sloan R. Alastair , Muir Robert , Whitehead Benjamin , New Thomas , Stevens Victoria , Macey Paul , Groenewald Conrad , Salomon Guy , Kahle Beth , Hollingsworth James
Published: February 2023

Namibia is situated within a stable continental region (SCR), far away from plate boundary zones, and is therefore not expected to be at risk of significant earthquakes; the largest events in the instrumental record have a moment magnitude of 5.5.  Despite this, a paleoseismic fault scarp on the Hebron Fault has been interpreted as indicating much larger events have occurred in the past.  In this study, we demonstrate that a relatively small area of SW Namibia contains four more major neotectonic fault scarps.  These 16-80 km long structures have vertical separations between 0.7-10.2 m and could produce earthquakes of Mw 6.4 or greater.  Some of these scarps are interpreted to have formed through repeated failure of the same segment and they highlight the potential for further seismicity that far exceeds the maximum observed magnitude in the national catalogue. We identify strong structural controls on the location and orientation of these fault ruptures which reactivate N-S and NW-SE trending zones of crustal weakness.  These structures may be driven by E-W extension associated with the distribution of gravitational energy caused by the anomalously high elevation of the Namibian Escarpment.  If this explanation of the driving stresses is correct, these and similarly oriented faults represent a previously unrecognised source of continuing seismic hazard.  The discovery of these major fault scarps suggests that fault studies should be incorporated into seismic hazard analyses of stable Southern Africa as has been done in Australia and other SCR regions. Their apparent spatial clustering also merits further study.  At this point it is not clear if this clustering indicates a region of elevated strain rate (relative the surrounding SCR) or alternatively, an area of exceptional preservation due to a semi-arid climate and extensive calcrete-cemented surficial deposits.
Radially anisotropic shear-wave velocity structure of northern India, Himalaya and Tibet
Authors: Ghosh Monumoy , Chakraborty Arijit , Dey Siddharth , Kharjana Inashua , Sharma Shubham , Bhattacharya Sankar N. , Mitra Supriyo
Published: February 2023

3-component regional waveforms for ~14700 raypaths sampling India, Himalaya and Tibet, have been used for multi-taper polarization analysis of surface waves between periods of 10 and 120 s. Rayleigh (LR) and Love (LQ) wave energy arriving at the station within +/- 10 degree of the theoretical back azimuth have been used to compute 1D path average fundamental mode group velocity dispersion. Theoretical dispersion of fundamental and first two higher modes have been computed using each 1D path average velocity structure constructed from CRUST1.0 over IASP91 mantle model. These are compared with the observed dispersion dataset to identify and remove those periods with higher mode overlap with the observed fundamental mode picks. The shortlisted dispersion datasets consist of ~90% of the original dataset. To ascertain the lateral variation in the group velocity, the observed dispersion has been used to compute 2D tomography maps of LR and LQ group velocities at discrete periods between 10 and 120 s. From these maps, seven 2D profiles across northern India, Himalaya and Tibet have been extracted for modeling the radially anisotropic shear-wave velocity structure of the lithosphere. Haskell-Thompson (H-T) matrix method is used to calculate synthetic LQ dispersion. For the LR dispersion, the H-T method with reduced delta matrix has been used, considering Vph≠Vpv and Eta≠1. The inversion scheme uses genetic algorithms (GA) to search the model space parameterized using Vsh, Vph, Xi and thickness for 3 crustal layers and 2 mantle layers underlain by a mantle half-space. Synthetic tests have been performed using theoretical LR and LQ dispersion curves, computed from global models with 5% and 10% anisotropy, introduced in the mantle layers. The fit to the synthetic LR and LQ dispersion data and the model recovery using GA inversion is satisfactory for such tests. This inversion scheme is being applied to the observed LR and LQ dispersion data from the seven profiles and the results will be presented.
Sequence of first flowering dates related to weather spells and plant traits
Authors: Menzel Annette , Neumair Matthias , Ankerst Donna
Published: February 2023

Climate warming can lead to phenological mismatches that are crucial for temporally coordinated (“matching”) ecosystem processes. Due to the lack of comprehensive data, these (potential) mismatches have often been inferred from diverging temporal trends or temperature responses. However, we go back to the original definition and analyze the apparent annual sequence/order of first flowering dates of multi-species data sets and their relationship to weather spells and plant traits. The old rhyme “Oak before ash, in for a splash” points to such weather-related changes in sequence; even if it does not lend itself to prediction. We hypothesize that (1) species with long-term similar flowering dates should have largely similar chilling and forcing requirements, but that (2) the altered fine-tuning in specific years is related to short-term weather spells (e.g. air temperate or solar radiation). In addition, we assume that (3) the latter response is related to specific plant traits.We used iconic multi-species datasets, such as Fitter and Fitter’s 1954-2000 flowering data of 385 species, and selected plant traits from the TRY database. Examining the sequence of phenological dates required solid data checking and enabled novel cleaning routines that simultaneously identified the annual holiday period of our phenological citizen scientists. Previous findings reported that traits related to competition and growth rate, such as plant height, SLA, and LDMC, and leaf biochemistry helped explain warming-induced phenological advances in flowering dates. It would be a significant advance if the results of our analyses could even reveal weather spell-driven phenological mismatches related to traits.
A Comparison of Aircraft SO2 Measurements in Remote and Polluted Marine Environments
Authors: Temple Loren , Young Stuart , Bannan Thomas , Batten Stephanie , Bauguitte Stéphane , Coe Hugh , Lee James , Matthews Emily , Pasternak Dominika , Rollins Andrew , Vallow Jake , Edwards Pete
Published: February 2023

Sulfur dioxide (SO2) plays a pivotal role in the chemistry of the troposphere, ultimately affecting the Earth’s radiation balance and climate. Within the atmosphere, SO2 is oxidised by gas- and aqueous-phase chemistry to sulfate and is therefore a major precursor to atmospheric aerosols, particularly in the remote marine atmosphere. Both the direct radiative forcing from aerosols and the indirect forcing from aerosol-cloud interactions are poorly understood and produce large uncertainties in climate models. Therefore, it is of interest to precisely quantify the concentration of atmospheric SO2 if we are to predict the effects of changing emission rates on both climate and air quality.Anthropogenic SO2 emissions have fallen dramatically in recent decades, resulting in significant reductions in atmospheric concentrations. Current commercial SO2 detection techniques, for example pulsed fluorescence, are no longer sensitive enough to detect trace levels of SO2 such as those found in remote marine environments. We report the development of a laser-induced fluorescence instrument for in situ SO2 measurements using a custom-built, tunable fiber-amplified laser system. Based on the system initially developed by Rollins et al. (2016), the University of York LIF-SO2 system has a detection limit of 50 ppt for 30 seconds and its relatively small size, weight and power requirements makes this instrument suitable for a variety of field campaigns.Here we present aircraft measurements of SO2 made by the York LIF-SO2 instrument on board the UK FAAM research aircraft in both the remote and polluted marine boundary layer. These are then compared to simultaneous SO2 measurements made by the University of Manchester I- chemical ionisation mass spectrometer (I- CIMS) instrument and the FAAM pulsed fluorescence commercial SO2 detector.
A model study on aerosol impact on extreme precipitation
Authors: Steensen Birthe , Alterskjær Kari
Published: February 2023

Observations and model results show an increase in extreme precipitation with global warming since the 1950s. During the last decades there have also been strong trends in anthropogenic aerosol concentration, aerosols that may affect cloud and precipitation processes that develop these extreme events. As human activities are the source of anthropogenic aerosols, they tend to be concentrated over highly populated regions where the potential cost and impact of extreme precipitation is high. In this study we investigate the link between extreme precipitation and aerosol particles in the atmosphere by using the cloud resolving WRF model. The model is set up with an aerosol-dependent cloud microphysics scheme that include processes such as; the increase in smaller droplets in aerosol rich clouds, the change in cloud reflective properties that can reduce surface evapotranspiration as well as a deepening of convective clouds and possible an increase in precipitation intensity. The model is run over several years in a stable climate to distinguish how these processes influence extreme precipitation separately from the extreme precipitation increase due to global warming. 
Calibration of a global hydrological model while simultaneously assimilating satellite-derived total water storage anomalies and in-situ streamflow observations
Authors: Schulze Kerstin , Gerdener Helena , Engels Olga , Kusche Jürgen , Döll Petra
Published: February 2023

Global hydrological models simulate water storages and fluxes of the water cycle, which is important for e.g. drought and flood predictions. However, model simulations are underlying uncertainties due to the inputs (e.g. climate forcing data), parameters, and model assumptions, resulting in disagreements with observations. To reduce these uncertainties, models are often calibrated against in-situ streamflow observations or compared against total water storage anomalies (TWSA) derived from the Gravity Recovery And Climate Experiment (GRACE) satellite mission. In recent years, TWSA data are integrated into some models via data assimilation.In this study, we jointly assimilated TWSA and streamflow observations into the WaterGAP Global Hydrology Model (WGHM) applying an Ensemble Kalman Filter. Simultaneously, model parameters are calibrated via state vector augmentation. Our simultaneous calibration and assimilation (CDA) approach was tested within the Mississippi River Basin from 2003 to 2016.First, we evaluated how the spatial resolution and study set up impact our CDA approach. Our results suggest that applying the CDA approach sequentially to all subbasins works better than applying the approach once to the entire Mississippi River Basin. Second, we compared the results of our CDA approach against uncalibrated model simulations as well as the results of the WGHM standard calibration. The CDA approach led to higher Nash-Sutcliffe efficiency (NSE) and lower root mean square error (RMSE) values (and thus a better agreement with the observations) regarding TWSA and streamflow than the uncalibrated WGHM simulations, which is in line with our expectations. In addition, it also resulted in higher NSE and lower RMSE values than the WGHM standard calibration in most subbasins. This was expected for the metrics regarding TWSA. Our expectations regarding the streamflow results were more complex: On one hand, our findings were surprising since the WGHM standard calibration approach is based on streamflow observations only and takes significantly more streamflow stations into account than the CDA approach. On the other hand, the results reflected that less parameters are calibrated and only the long-term averages of the streamflow observations are considered in the WGHM standard calibration approach.
Enhancing PPP-AR with satellite attitude data from ORBEX files
Authors: Glaner Marcus Franz , Weber Robert
Published: February 2023

Over the past decades, Precise Point Positioning (PPP) has become a well-established technique for determining the user's position with the signals of Global Navigation Satellite Systems (GNSS). PPP is characterized by applying precise satellite products (orbits, clocks, and biases) and accurately modeling a wide range of error sources to estimate the user's position. This way, a position accuracy at the centimeter or even millimeter level is accomplished. However, the convergence time until the coordinates have reached this accuracy is well known as the primary concern of PPP. In that regard, PPP with integer ambiguity resolution (PPP-AR) has proven as an effective way to dramatically reduce the convergence time of PPP, especially in the east coordinate component.Currently, the so-called Orbit Exchange (ORBEX) format is under revision. Its main philosophy is larger flexibility for the description of the satellite state than in different existing formats. Besides other advantages, the ORBEX format can provide information on the satellite orientation in attitude records. Several Analysis Centers have started to provide such data in addition to their satellite orbits, clocks, and biases. Consequently, the PPP user can accurately calculate the satellite orientation instead of relying on the usually adopted IGS convention.Since the satellites' orientation is essential for accurately modeling several error sources and recovering the integer property of the phase ambiguities, the performance of PPP is usually improved by using accurate satellite attitude information. This contribution illustrates the effect of attitude data on ambiguity fixing, convergence time (time to first fix), and coordinate accuracy in several test cases. Especially, satellite eclipse seasons are investigated. The PPP calculations are performed with our software raPPPid, the PPP module of the Vienna VLBI and Satellite Software (VieVS PPP).
Dynamic modeling of plant uptake and leaching of pesticides applied at an apple orchard
Authors: Rein Arno , An Quanshun , Wu Yangliu , Li Dong , Hao Xianghong , Pan Canping
Published: February 2023

Apple production is a major agricultural activity in many regions around the globe. Over the past decades, a range of different pesticides have been used for preventing fungal and insect infestations. Evaluating the fate of pesticides in plants and soil is important for determining human health risks arising from chemical residues in fruits as well as ecological risks, among others resulting from pesticide fate in soils and eventually leaching to groundwater.This study aimed at improving the understanding of complex fate and transport processes interacting in the soil-plant system of an apple orchard. Field experiments were done with different insecticides and fungicides that are frequently applied in agricultural practice. Pesticide concentrations in soil and different plant parts were observed at different times under a multiple pesticide applications scenario.  A coupled soil-plant model was set up for numerically simulating pesticide fate and comparison with observed pesticide concentrations. This model considers a tipping buckets approach for soil water and solute transport, linked with a dynamic numerical model for plant uptake and translocation of chemicals within plants, implementing a fruit growth model for explaining the fruit growth dilution. Moreover, risks posed for food safety were estimated.This model approach was successful for describing observed pesticide residues. Up to 25% of the applied chemicals were deposited on leaves and up to 0.6% on fruits, and up to 61% entered the topsoil directly after application. A decrease in fruit concentration was observed, which could be explained by biodegradation and growth dilution as the main contributions, as well by wash-off. First estimates of dietary risks indicated that the ingestion of the treated apples may not lead to relevant acute or chronic human health risks. The contribution of the different pathways leading to pesticide residues and their dynamics in plant material was highly influenced by precipitation patterns, fruit growth dilution and pesticide characteristics. Our model approach can contribute to an improvement of process understanding concerning the fate of pesticides in apple orchards and pesticide utilization. It has a high potential for supporting decision making with respect to food safety and minimizing risks associated to pesticide use.