bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimizing Irrigation Strategies for Mitigating Drought Stress in Reforestation Areas: Lessons from a Drought Stress Experiment
Authors: Hahn Leonie , Schmidt Markus , Lorz Carsten , Rothe Andreas , Rammig Anja , Zang Christian
Published: March 2024

The increasing frequency of drought events in recent years has become a major hurdle for reforesting forests after natural disturbances in many areas globally, including parts of Central Europe. As an example, reforestation projects after bark beetle disturbances have faced notable failures and losses due to prolonged drought conditions in Northern Bavaria (Germany). Irrigation is a potential measure increasing reforestation success and is currently funded by the regional government. However, historically irrigation was not a common technique in this area and there is a lack of both practical and scientific knowledge concerning irrigation strategies. The optimal timing for the irrigation of the saplings as well as the water amount applied are crucial aspects in this context.This study addresses this knowledge gap by conducting a drought stress experiment within a greenhouse environment, focusing on four commonly planted tree species prevalent in our study region in northern Bavaria. Various approaches were explored to reliably detect drought stress and identify the irrigation demand both concerning timing and amount of water applied: the experimental design integrates environmental data with ecophysiological measurements and employs drought stress indices derived from close-range remote sensing. The most promising methodology for detecting the irrigation demand, identified through rigorous experimentation, will be further explored on forest sites post-planting. Implementing such optimized irrigation strategies holds promise for safeguarding reforestation endeavors, particularly in regions prone to drought, and contributes to the sustainable management of forest ecosystems and water usage.
Temperature Decoupling on the World’s Mountain Glaciers
Authors: Shaw Thomas , Miles Evan , Buri Pascal , McCarthy Michael , Guyennon Nicolas , Carturan Luca , Salerno Franco , Pellicciotti Francesca
Published: March 2024

The development of a katabatic boundary layer can decouple near surface air temperature changes over glaciers from their surrounding environment during the ablation season, impacting the response of glaciers to ongoing climate change. Current glacier modelling efforts mostly neglect such processes and assume that glacier mass balance will evolve linearly with large-scale (ambient) air temperature changes into the future. Recent work has established that glacier evolution with climate will likely be non-linear, including in its sensitivity to ambient temperature. While past studies have explored this near-surface decoupling at a number of individual sites, the derived patterns have not been generalisable. We compile an extensive new inventory of on-glacier weather station data to explore this phenomena, with over 175 glacier-year sets, including more than 350 individual AWS locations and > 1.3 million hourly air temperature observations. Combining in situ on-glacier and near-glacier meteorological data with reanalysis and surface topography information we are able to explore how the climatic setting and local processes (e.g. wind interactions and local topography) may shape a glacier’s ability to become more or less coupled to the ambient climatic warming. Across all sites studied we find a mean (std.) cold bias of on-glacier vs. ambient temperatures of 1.22±1.35°C and a ratio of above-ice temperature changes compared to ambient, non-glacier conditions of 0.75±0.17 (i.e. a 1°C increase off-glacier equals ~0.75°C change on-glacier). We highlight the relevance of this to glacier modelling applications at select glacier sites and demonstrate hotspots around the world where above-glacier temperature changes during the recent decades are likely to have become decoupled from background warming. Preliminary results show how larger glaciers in maritime climates and those with minimal debris cover are most likely to decouple from ambient warming. However, as glaciers shrink and debris cover expands, the influence of the climatic setting in controlling this decoupling is diminished.
2152
Authors: Yao Meng , Kang Ronghua
Published: March 2024

It has been recognized recently that trees can assimilate NO2 directly through leaf stomata. Both laboratory and field studies have measured the foliar NO2 deposition velocity, which could be determined by some environmental factors, e.g. light irradiation intensity, ambient NO2 concentration, and leaf characteristics. However, the NO2 uptake capacity and allocation of foliar uptake NO2 under these environmental factors remain unclear. To clearly understand the foliar NO2 uptake process and refine the forest NO2 uptake models, we conducted a dynamic 15NO2 fumigation experiment.We selected Fraxinus mandshurica (F. mandshurica), Pinus koraiensis (P. konraiensis), Quercus mongolica (Q. mongolica), and Larix gmenilii (L. gmenilii) saplings, four dominant tree species in temperate forests of northeastern China, as our experimental materials. Meanwhile, we chose a pair of broad-leaved and coniferous tree species (F. mandshurica and P. konraiensis) to perform fumigation experiment under dark/light irradiation and another pair (Q. mongolica and L. gmenilii) to perform fumigation experiment with soil N addition. All saplings were dynamically fumigated with 50 ppb 15NO2 for 8 h and destructively sampled immediately after fumigation. We rinsed the samples surface with purified water, dried and grinded all samples, then measured the 15N abundance in leaves, twigs, stems and roots with EA-IRMS.The results showed that tree saplings can absorb NO2 under both dark and light irradiation treatments. The total 15N recovery ranged between 30 to 80% under the light condition in all species. Under the dark condition, the total 15N recovery were (29.8±9.16) % and (1.1±0.47) % for F. mandshurica and P. konraiensis, which were significantly lower than under the light condition, (59.6±5.2) % and (8.8±2.5) %, respectively. With the soil N addition, the total 15N recovery in Q. mongolica ((56.2±8.8) %) were significantly larger than non-N addition ((27.6± 4.8) %), while L. gmenilii showed the opposite result that the total 15N recovery ((31.7±7.8) %) significantly decreased, compared to that without N addition ((73.6±4.3) %). These results are likely attributed to different amount of N demand for different tree species, more N needed for Q. mongolica than L. gmenilii. Moreover, coniferous species could assimilate more N through foliar uptake than broad-leaved species, probably due to bigger leaf surface areas of coniferous trees. After 8 h fumigation, the largest proportion of 15NO2 was recovered in leaves in all species and treatments, accounting for 60-97%, which indicates that NO2 stays in leaves in a short-term period after foliar assimilation. However, further studies are needed to explore the transformation of foliar incorporated NO2 to other organs in a long-term scale.This study quantified the foliar NO2 uptake capacity of different tree species and figured out the effects of light irradiation and soil nitrogen availability on foliar NO2 uptake. Our results would provide references for the model estimation of canopy NO2 uptake magnitude at a regional scale.
A possible cartographical data source for historical magnetic field improvement: The direction of the section north of the Habsburg first military survey
Authors: Koszta Benedek , Timár Gábor
Published: March 2024

On some maps of the first military survey of the Habsburg Empire, the upper direction of the sections does not face the cartographic north, but makes an angle of about 15° with it. This may be due to the fact that the sections were subsequently rotated to the magnetic north of the time. Basically, neither their projection nor their projection origin is known yet.In my research, I am dealing with maps of Inner Austria, the Principality of Transylvania and Galicia (nowadays Poland and Ukraine), and I am trying to determine their projection origin. For this purpose, it is assumed, based on the archival documentation of the survey, that these are Cassini projection maps. My hypothesis is that they are Graz, Cluj Napoca or Alba Julia and Lviv. I also consider the position of Vienna in each case, since it was the main centre of the survey.The angle of rotation was taken in part from the gufm1 historical magnetic model back to 1590 for the assumed starting points and year of mapping. In addition, as a theoretical case, I calculated the rotation angle of the map sections using coordinate geometry. I then calculated the longitude of the projection starting point for each case using univariate minimization. Since the method is invariant to latitude, it can only be determined from archival data.Based on these, the starting point for Inner Austria from the rotation of the map was Vienna, which is not excluded by the archival sources, and since the baseline through Graz also started from there, it is partly logical. The map rotation for Galicia and Transylvania also confirmed the starting point of the hypothesis.  Since both Alba Julia and Cluj Napoca lie at about the same longitude, the method cannot make a difference there; and the archival data did not provide enough evidence. In comparison, the magnetic declination rotations yielded differences of about 1°, which may be due to an error in the magnetic model.On this basis, I have given the assumed projections of the three maps with projection starting points, and developed a method for determining the projection starting points of the other rotated grid maps. The results suggest that there is a very high probability that the section network was rotated in the magnetic north direction, and thus provide a way to refine the magnetic declination data at that time.With this method I managed to give new indirekt magnetic declinations data from Central-East Europe, which can help to improve the historical magnetic field models. The main reason for this is that we don’t have any measurement from that region.Furthermore the difference beetwen the angle of the section north and the declination data from gufm1 always 0.8-1°. Maybe there are systematical data error at that region.Supported by the ÚNKP-23-6 New National Excellence Program of the Ministry for Culture and Innovation from the source of the National Research, Development and Innovation Fund.
Microbial Mechanisms Governing the Reduction of CH4 Emission in Coastal Wetlands under Elevated CO2 Conditions
Authors: Kang Hojeong , Yang Yerang , Noyce Genevieve , Megonigal Patrick
Published: March 2024

Elevated levels of CO2 are known to enhance CH4 emissions from wetlands due to the combined effects of increased plant biomass and greater carbon availability for methanogens. However, recent findings have demonstrated a decrease in CH4 emissions under elevated CO2 conditions in coastal wetlands, primarily attributed to the oxygen priming effect. Despite this knowledge, direct evidence elucidating the microbial processes underlying this reduction remains elusive. In this study, we employed mRNA-based analysis to identify the active microorganisms responsible for CH4 dynamics.Under elevated CO2 conditions, we observed lower methanogen abundances compared to ambient CO2 levels, suggesting that the oxygen priming effect inhibited the activity of methane-producing microbes. Intriguingly, no significant differences were found for methanotrophs, whose impact on wetland sediments may be minimal. Additionally, there was no notable change in the abundance of dsrA genes, indicating that the reduction in CH4 emission was not a result of carbon substrate competition with sulfate reducers. This research contributes valuable insights into the microbial mechanisms governing CH4 emissions in coastal wetlands under elevated CO2 conditions.
Nonlinear 21st century increase of Greenland Ice Sheet runoff into Disko Bay surface water recorded by long-lived coralline algae
Authors: Hetzinger Steffen , Halfar Jochen , Tsay Alexandra
Published: March 2024

Greenland is particularly vulnerable to ongoing anthropogenic climate change and observational data document recent rapid mass loss of many of the Greenland Ice Sheet (GIS) glaciers. Mass loss of the GIS represents a major contributor to global sea level rise, but uncertainties in future projections are large. A recent acceleration in mass loss has been observed, with 2012 and 2018/19 record years documented by direct observations. However, estimates of melt variability and glacier runoff remain uncertain before the satellite era and the influence on surface ocean waters is unclear. In general, available observational records from high latitudes are sparse and short. Models require high-resolution data of past variability to resolve how fast the GIS reacts to warming.Past climate can be reconstructed from natural proxy archives. In high latitudes, however, most proxy time series utilised to date come from indirect land-based proxies. Calcified coralline algae are important shallow-marine calcifiers that grow attached to the seafloor and have emerged as subannual-resolution climate recorders for the extratropics. By analyzing long-lived coralline algae from Disko Bay, West-Greenland, in close proximity to Jakobshavn Glacier, we address this data gap. Jakobshavn Glacier is one of the largest glaciers in Greenland and the single largest source of mass loss from the GIS over the last 20 years. Sclerochronological analysis and ultra-high-resolution laser ablation ICP-MS data from calcified coralline algae (Clathromorphum compactum) provide seasonally-resolved records that capture the impact of surface temperature warming and glacier runoff on coastal Arctic environments. Algal Ba/Ca ratios track past glacier-derived meltwater input to the ocean surface layer and we report an unprecedented nonlinear increase in Jakobshavn glacier runoff into Disko Bay in the last 20 years. Our chronology from southern Disko Bay sites shows a distinct increasing trend from the early 2000s, recording the acceleration of GIS glacier mass loss and matching recent years of record amounts of ice loss in satellite data. The rate of increase in Ba/Ca (a runoff proxy) is unprecedented over at least the last 100 years, highlighting the rising influence of global warming on Arctic coastal ecosystems. The new algal chronology provides a long-term perspective on high-resolution variability in Jakobshavn Glacier runoff into Disko Bay, extending before observations, and confirming model data.
Feature Selection for Lidar Point-Cloud Classification based on Overlapping Regions
Authors: Hess Max , Bookhagen Bodo , Rheinwalt Aljoscha
Published: March 2024

The global availability of dense point clouds provides the potential to better assess changes in our dynamic world, particularly environmental changes and natural hazards. A core step to make use of modern point clouds is to have a reliable classification and identify features of importance for a successful classification. Feature selection routines attempt to minimize the number of features by retaining as much information as possible about the classes. Our new approach attempts to achieve high classification results while being applicable to a wide variety of classifiers. We present an approach for classifier independent feature selection based on the overlap of features. The computative-extensive calculation of overlapping regions in multi-dimensional spaces is achieved by an optimized GPU-based Monte Carlo integration. This novel approach is compared against several feature selection routines and the selected features are tested with different classifiers. In our application experiments, we compare geometric, echo-based and full-waveform features of lidar point clouds to obtain the most useful sets of features for separating ground and vegetation points into their respective classes. Different scenarios of suburban and natural areas are studied to collect various insights for different classification tasks. In addition, we group features based on various attributes such as acquisition or computational cost and evaluate the benefits of these efforts in terms of a possible better classification result.
A physiological approach to parameterising variable Diatom Si:N ratios using a quota model to reproduce nutrient addition experiments in the Southern Ocean
Authors: Harper Jacob , Moore Mark , Ward Ben , Martin Adrian , Tyrrell Toby
Published: March 2024

The Si:N ratio of diatoms in the Southern Ocean (SO) is increased in response to iron limitation resulting in enhanced removal of Si from the surface waters that are entrained into the Subantarctic Mode Water (SAMW) leaving it Si deficient. Biogeochemical models usually employ direct parameterisations to represent this phenomenon empirically, however minor differences in how this process is parameterised can lead to large disparities in model results due to the large influence of SAMW on productivity in the lower latitudes. We explore the complexities of parameterisation using data from a recent cruise of the ‘Carbon Uptake and Seasonal Traits in Antarctic Remineralisation Depth’ (CUSTARD) project. This project undertook a series of factorial nutrient addition experiments including Fe, Mn and Si, along 89° W between 54° S and 59.99° S. Experimental results reinforced that Si:N ratio is dependent not only on Fe but also Si availability. To properly reproduce this data, a quota model was altered to allow phytoplankton to uptake and store luxury quantities of nutrients to then be used for growth from internal pools. This model was able to successfully reproduce quantitative patterns of nutrient limitation and the Fe-Si dependency of diatom Si:N ratios through an explicit physiological approach without the need for a direct parameterisation. Such methodology is both more authentic to the natural control of diatom stoichiometry and may avoid the potential for artificial responses created by direct parameterisations.
Forecasting Strong Subsequent Earthquakes in Japan Using NESTORE Machine Learning Algorithm: preliminary results 
Authors: Gentili Stefania , Chiappetta Giuseppe Davide , Petrillo Giuseppe , Brondi Piero , Zhuang Jiancang , Di Giovambattista Rita
Published: March 2024

NESTORE (Next STrOng Related Earthquake) is a machine learning algorithm for forecasting strong aftershocks during ongoing earthquake clusters. It has already been successfully applied to Italian, Greek and Californian seismicity in the past. A free version of the software in MATLAB (NESTOREv1.0) is available on GitHub. The method is trained on the region under investigation using seismicity characteristics. The obtained region-specific parameters are used to provide the probability, for the ongoing clusters, that the strongest aftershock has a magnitude greater than or equal to that of the mainshock - 1. If this probability is greater than or equal to 0.5, the cluster is labeled as type A, otherwise as type B. The current version of the code is modular and the cluster identification method is based on a window approach, where the size of the spatio-temporal window can be adjusted according to the characteristics of the analyzed region.In this study, we applied NESTORE to the seismicity of Japan using the Japan Meteorological Agency (JMA) catalogue from 1973 to 2022. To account for the highly complex seismicity of the region, we replaced the cluster identification module with software that uses a stochastic declustering approach based on the ETAS model.The analysis is performed in increasing time intervals after the mainshock, starting a few hours later, to simulate the evolution of knowledge over time. The analysis showed a high prevalence of clusters where there are no strong earthquakes later than 3 hours after the mainshock, leading to an imbalance between type A and type B classes.NESTORE was trained with data from 1973 to 2004 and tested from 2005 onwards. The large imbalance in the data was mitigated by carefully analyzing the training set and developing techniques to remove outliers. The cluster type forecasting was correct in 84% of cases. Funded by a grant from the Italian Ministry of Foreign Affairs and International Cooperation and Co-funded within the RETURN Extended Partnership and received funding from the European Union Next-GenerationEU (National Recovery and Resilience Plan - NRRP, Mission 4, Component 2, Investment 1.3 – D.D. 1243 2/8/2022, PE0000005) and by the NEar real-tiME results of Physical and StatIstical Seismology for earthquakes observations, modeling and forecasting (NEMESIS) Project (INGV).
Multiday mesoscale soil moisture persistence and atmospheric predictability – an illustration from the Sahel
Authors: Taylor Christopher , Klein Cornelia , Harris Bethan
Published: March 2024

The hydro-climate of the Sahel is dominated by organised Mesoscale Convective Systems (MCSs), which typically bring intense rain every few days during the West African Monsoon season. MCSs leave a swath of wet soil often hundreds of kilometres across, which in turn create strong spatial patterns of surface fluxes of heat and water back into the atmosphere. Previous studies have shown that soil moisture patterns exert a strong control on the initiation and propagation of MCSs, significantly enhancing the predictability of convection on scales of 10 – 100s km. Here, we use satellite observations to examine how this strong, locally negative, soil moisture-precipitation feedback evolves and impacts rainfall patterns over a series of storms.We track the response of the surface and atmosphere to over 5,000 MCS events from the period 2004-2020, using a combination of satellite-derived products (Land Surface Temperature; LST, soil moisture, Vegetation Optical Depth, rainfall, cloud-top temperature). Initial anomalies in LST and soil moisture weaken rapidly in the 3-4 days after the MCS, particularly in climatologically wetter regions. However, a statistically significant memory of the original MCS event still remains in surface anomalies out to 20 days. In terms of rainfall, we see a strong suppression of convection in the first 48 hours after the MCS in areas which initially received heavy rain. There is also some evidence of enhanced MCS activity around the edges of the original swath in the first 4 days. The persistence over several days of mesoscale rainfall patterns anti-correlated with the original MCS point to an important role for surface-atmosphere feedbacks. Synoptic forcing cannot explain the finer scale rainfall response, whilst post-MCS cold pool effects are too short-lived. On longer time scales (5-20 days) in climatologically drier areas, we also find a weak but statistically significant enhancement of rainfall around the original initiation zone.These results have important implications for rainfall forecasting on scales of tens to several hundred kilometres. Pre-existing soil moisture heterogeneity provides strong predictability of where future convection will occur under favourable synoptic conditions. This provides skill out to 2-4 days, but strongly depends on regional rainfall frequencies. Because new MCSs create new soil moisture patterns, the combination of storms every few days and a strong negative land feedback at the mesoscale actively degrades longer term predictability within the rainy season, effectively limiting intra-seasonal to seasonal forecast skill for severe weather.
On the temporal variations of near-surface seismic structure of Taiwan and its geological inferences
Authors: Chen Hui-Chu , Gung Yuancheng , Lee Hsin-Yu , Chen Li-Wei
Published: March 2024

We report on the temporal variations of the near-surface (< 500 m) seismic structure (Vp, Vs, and Vs anisotropy) of Taiwan using the empirical Green’s functions of body waves between vertical station pairs at 60 borehole sites. In our previous work, the obtained near-surface anisotropy are categorized into stress-aligned anisotropy (SAA) and orogeny parallel anisotropy (OPA). Since all the major geological units of Taiwan are well sampled by borehole arrays, and drilling data for 52 sites are available, we were able to find that OPA is typically stronger than SAA, SAA strength is generally higher in sedimentary rocks, igneous rocks, and gravel sediments compared to fine-grained sediments, and OPA is more pronounced in foliated metamorphic rocks than in dipping sedimentary strata. In this study, we aim to address the following specific questions with the obtained results: (1) How do the temporal variations of near-surface seismic properties in different geological units of Taiwan correlate with seismic activity or nearby earthquake events? (2) Are there distinct patterns in the temporal variations of anisotropy strength based on the specific geological composition? (3) Do sites characterized by OPA exhibit different temporal variations in response to seismic activity compared to sites dominated by SAA?
On the turbulent structures generated by intruding downslope rotating gravity currents
Authors: Axel Tassigny , Maria Eletta Negretti , Achim Wirth
Published: March 2024

Gravity currents play a crucial role in the formation of deep waters in the ocean, contributing to the vorticity and energy transfers towards the ocean interior. We present results from an experimental study on downslope intruding and rotating gravity currents into an initially two-layer stably stratified ambient at high buoyancy Reynolds numbers. A new turbulent process of downslope transport, intermittent and localized, is identified, taking the form of cascades. The lifetime of cascades presents a power law relationship, and the related transport does not exhibit any characteristic length scale, suggesting self-organized criticality. Cascades reveal to be the main contributor to the vorticity and turbulence in the ocean interior, with a dependence on the Coriolis parameter and the density anomaly to the surrounding ambient. Vorticity is produced both by the spreading of the cascade into the interior, and by the meandering and the break up of the deep boundary current (formed from downward Ekman transport). When the intrusion spreads at the pycnocline only, anticyclonic eddies are formed in the intrusion and top layers, whereas for intrusions spreading through the full bottom layer, vortices of both signs are generated due to bottom friction. The turbulence in the receiving ambient reveals to be horizontally isotropic, non-stationary and non-homogeneous. In the intrusion area close to the slope, the turbulence is forced by energy injection at the penetration length scale through the cascades. The central area far from the boundaries is characterized, instead, by freely evolving two-dimensional turbulence, forced at large scales. 
The expansion of forests and the practice of irrigated agriculture contribute to reduced river flows in southern Europe during dry years
Authors: Vicente Serrano Sergio Martín , El Kenawy Ahmed , Peña-Angulo Dhais , Lorenzo-Lacruz Jorge , Murphy Conor , Hannaford Jamie , Dadson Simon , Stahl Kerstin , Noguera Iván , Franquesa Magí , Fernández-Duque Beatriz , Domínguez-Castro Fernando
Published: March 2024

This research examines the changes in annual streamflow across Europe from 1962 to 2017, with a specific focus on the correlation between streamflow trends and climate dynamics, as well as physiographic and land cover characteristics. The spatial distribution of streamflow trends aligns closely with climate patterns, suggesting a climate-related influence. However, a detailed analysis at the basin scale reveals that the significant decline in streamflow in southern Europe cannot be solely attributed to climate dynamics. Instead, a discernible negative trend linked to non-climate factors becomes apparent. Specifically, our study indicates that the primary drivers of negative streamflow trends in southern Europe, especially during dry years, are forest growth and irrigated agriculture. This is attributed to the higher proportion of green water consumption compared to blue water generation. These findings hold substantial implications, particularly in the context of widely adopted nature-based solutions for addressing climate change. This includes concerns about carbon sequestration through forests and the planned expansion of irrigated agricultural lands in central and northern European countries to meet growing crop water demands. Such developments may potentially reduce the availability of water resources, leading to an increased frequency and severity of low flow periods.
Future prolonged ozone pollution season over the North China Plain driven by emission reductions and climate change
Authors: Li Ke , Liao Hong
Published: March 2024

In 2021, the World Health Organization (WHO) introduced for the first time the standard for the peak season ozone (six-month mean MDA8 ozone) of no more than 60 μg m-3. Typically, the warm season from April to October is often considered as the peak ozone season. However, the highly polluted North China saw the prolonged ozone pollution season based the national surface network measurement, which is threatening public health and the mitigation of PM2.5 pollution. In order to accurately quantify the risk of this ozone season exposure, here this study proposes some methods to quantitatively characterize the active ozone photochemistry season based on the Ox (NO2+O3) and ozone-temperature relationship. Firstly, we found that the active ozone photochemistry season has extended by about four weeks in the course of fast emission reductions from 2014-2022. Then, combined with atmospheric chemical modeling and future SSP scenarios, it is found that deep emission reductions and climate warming will significantly increase the length of peak ozone season over the North China Plain.
Tectonic architecture of the northern Dora-Maira Massif (Western Alps, Italy): field and geochronological data
Authors: Ballèvre Michel , Manzotti Paola , Nosenzo Francesco , Krona Mikaela , Poujol Marc
Published: March 2024

High-pressure and ultra-high-pressure metamorphic terrains display an internal architecture consisting of a pile (or stack) of several coherent tectonic thrust sheets or units. Their identification is fundamental for understanding the scale and mechanisms active during subduction and exhumation of these crustal slices. This study investigates the geometry of the northern Dora-Maira Massif and the kinematics of the major tectonic boundaries, combining field and geochronological data. The tectonic stack of the northern Dora-Maira Massif comprises the following units. The lowermost unit (the Pinerolo Unit) is mainly characterized by Upper Carboniferous fluvio-lacustrine (meta-)sediments. The Pinerolo unit is overthrust by a pre-Carboniferous basement. The latter is subdivided in two tectonic units (the Chasteiran and Muret Units) with different Alpine metamorphism (ultra-high-pressure and high-pressure, respectively). The pre-Carboniferous basement of the Muret Unit is thicker than previously thought for two main reasons. Firstly, some paragneisses, traditionally assumed to be Carboniferous and/or Permian in age, display a dominant detrital zircon source at about 600 Ma. Secondly, three samples of the Granero Orthogneiss, previously assumed to be a Permian intrusive body, have provided zircon U-Pb ages of 447 ± 3 Ma, 456 ± 2 Ma and 440 ± 2 Ma, indicating a late Ordovician or early Silurian age for the protoliths. The uppermost unit (the Serre Unit) comprises porphyritic (meta-) volcanic and volcaniclastic rocks dated to the Permian (271 ± 2 Ma), on top of which remnants of the Mesozoic cover is preserved. Detailed mapping of an area about 140 km2 shows that (i) the ultra-high pressure Chasteiran Unit is localized at the boundary between the Pinerolo and Muret Units, (ii) the Granero Orthogneiss may be considered as the mylonitic sole of the Muret Unit, characterized by a top-to-W sense of shear, and (iii) the contact between the Muret and Serre Units displays ductile-to brittle structures (La Fracho Shear Zone), indicating a top-to-the-NW displacement of the hangingwall with respect to the footwall. A final episode of brittle faulting, cutting across the nappe stack (the Trossieri Fault), indicates an extensional stage in the core of the Alpine belt, as previously documented in more external zones. This work provides a necessary and robust basis for an accurate discussion of processes acting during continental subduction of the Dora-Maira Massif.
 Investigation of vertical column densities and profiles of water vapor using look-up table method with MAX-DOAS
Authors: Li Suwen , Zhou Chuang , Mou Fusheng
Published: March 2024

Abstract: Water vapor is one of the crucial greenhouse gases in the atmosphere, and the accurate determination of its concentration and vertical profiles is essential for investigating regional water cycling, and climate-environmental changes. This study investigated a method for retrieving atmospheric water vapor vertical column densities (VCDs) and profiles using the Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) technique. The approach involves a two-step inversion: first, aerosol extinction profiles are inverted, followed by the inversion of water vapor profile information. A parameterized look-up table method is employed during profile inversion, minimizing reliance on prior information. The study focused on the Huaibei region, using MAX-DOAS to retrieve O4 absorption aerosol profiles. By minimizing the cost function and employing the look-up table method, water vapor profiles are inverted, including parameters such as H2O VCD, water vapor weighting factors in the boundary layer (ω), and boundary layer height (h). Results indicated that, during the observation period in the Huaibei region, water vapor was  primarily concentrated below 1 km, gradually decreasing with altitude. The comparison of the H2O VCDs retrieved using the look-up table method with the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 model and geometric approximation demonstrated a strong agreement in diurnal trends (correlation coefficients: 0.93 and 0.98, respectively). In order to understand the sources of water vapor in different vertical layers in the Huaibei region, a 24-hour backward trajectory clustering analysis was conducted using the HYSPLIT model based on the observed wind fields during the monitoring period. The results indicated that at 500 meters altitude, water vapor primarily originated from the southeast direction, while at 1 km and 2 km altitude, the dominant source of water vapor was from the southwest direction. The study demonstrates the successful inversion of tropospheric water vapor vertical column densities and profiles, providing reliable technical support for obtaining regional water vapor information.
Growth and drought resilience of planted conifers and broadleaves in the semi-arid Northern China.
Authors: Li Jitang , Xie Yuyang , Julio Camarero Jesús , Gazol Antonio , González de Andrés Ester , Ying Lingxiao , Shen Zehao
Published: March 2024

Under warmer and drier climate scenarios, the growth and resilience of forests will be critically affected by more frequent and severe droughts. Since the 1970s, China has launched several afforestation programs aimed at regional ecological protection, playing an important role for reaching carbon neutrality by 2060.This study provided a detailed analysis of the growth suitability of the main planted conifers (Pinus sylvestris var. mongolica, Pinus tabulaeformis) and broadleaves (Populus spp., Robina pseudoacacia) in the semi-arid northern China. We compared the radial growth trends of plantations and their responses to extreme droughts from 1980 to 2018.Growth of most plantations has significantly increased, but broadleaves showed recent growth reductions in the past decade, which may be related to tree age and reduced soil water content. Nevertheless, under warmer climate scenarios, growth of plantations is forecasted to continue increasing. Broadleaves showed a better post-drought recovery, probably linked to their anisohydric behavior, than conifers, which presented a better resistance to drought. Growth of conifers depended more on warmer temperature and better precipitation conditions during the growing season, whereas broadleaves mainly reacted to warm temperature. Additionally, pre-drought growth levels weakened resilience components, while post-drought precipitation compensated drought-induced growth deficit. Growth and resilience were negatively related to tree age, whilst higher stand density reduced growth. This assessment and projections of growth and drought resilience indicate the sustainability of most plantations in semi-arid regions, but future warmer and drier conditions may lead to an uncertain future regarding forest health and reduce their carbon sink potential.Keywords: Growth trends; Drought resilience; Tree-ring analysis; Plantations; Three-North Shelter Forests Program.
Snowmelt Contribution to Seasonal Baseflow Dynamics in Mountain Catchments
Authors: Acheampong Johnmark Nyame , Jenicek Michal
Published: March 2024

Understanding runoff processes in mountain catchments is pivotal in hydrology. Elevated temperatures reducing snow water equivalent (SWE) significantly impact runoff dynamics and may reduce groundwater recharge. While snow is more effective in generating runoff compared to liquid precipitation, diminished snow accumulation and earlier snowmelt further exacerbate these impacts. Recent mesoscale studies challenge conventional notions of baseflow, revealing diverse landscape roles, yet linking baseflow to catchment attributes remains fragmented. This research delves into how snowmelt influences both baseflow and catchment runoff dynamics. Employing an "effect-tracking" algorithm, we analyse the distinct impacts of individual water sources, examining the variability of annual runoff. Utilizing the HBV model on a catchment scale for 59 mountain catchments located in six mountain regions in Czechia for the period 1980-2014 showed decreasing snow storage in some of the mountain regions and an overall shortening of the snow cover period. Our investigation revealed elevation-related rises in annual and summer baseflow fractions. These increases are notably heightened during periods of increased snowfall. Snow accumulation emerges as an important factor shaping baseflow dynamics, emphasizing elevation-dependent baseflow increments in snow-rich conditions. The findings not only highlight the critical influence of factors such as elevation, snowmelt, and altered snow accumulation patterns on baseflow dynamics but also underscore their broader implications. Understanding these intricate mechanisms holds promise for better water resource management and forecasting in mountainous catchments.
Introducing ELSA: An isochronal model for ice sheet layer-age tracing
Authors: Rieckh Therese , Born Andreas , Robinson Alexander , Law Robert , Gülle Gerrit
Published: March 2024

We are presenting the ice-sheet layer-age tracer ELSA (Englacial Layer Simulation Architecture) — a model that uses a straightforward method to simulate the englacial stratification of large ice sheets — as an alternative to Eulerian or Lagrangian tracer schemes. ELSA’s vertical axis is time; individual layers of accumulation are modeled explicitly and are isochronal. ELSA is not a stand-alone ice-sheet model, but requires uni-directional coupling to another model providing ice physics and dynamics (the “host model”). Via ELSA’s layer tracing, the host model’s output can be evaluated throughout the ice sheet interior using ice core or radiostratigraphy data. We show results regarding the stability and resolution-dependence of this coupled modeling system using simulations of the last glacial cycle of the Greenland ice sheet with Yelmo as the host model. We present options for making ELSA computationally efficient enough for ensemble runs, as well as requirements for offline forcing of ELSA with output from a range of existing ice-sheet models. ELSA is an open source project and available on git (https://git.app.uib.no/melt-team-bergen/elsa) for the ice sheet modeling community.
Integrative approaches to assess holistic ecosystem reactions to environmental threats and perturbations - an ecohydrological perspective
Authors: Dubbert Maren , Dahlmann Adrian , Dubbert David , Kübert Angelika , Demir Gökben , Vaidya Shrijana , Augustin Jürgen , Hoffmann Mathias
Published: March 2024

The ongoing Climate Crisis significantly deflects ecosystems worldwide and threatens their sustainable functioning. Hydrologically, we face an increase in extreme hydrological events, increasing the importance of a comprehensive knowledge of the ecosystem water cycle to assess ecosystem stability in forest and other ecosystems. At the same time, water cycling is intertwined with carbon and nutrient cycling and system responses to environmental stress being regulated by a complicated feedback loop of e.g. environmental factors, ecosystem structure, geomorphology, or species adaptation strategies. Hence, to achieve a holistic understanding of (eco-)hydrological processes and their responses to Climate and anthropogenic threats – and more importantly their role in overall ecosystem sustainability -  we need to develop cross-discinplinary, cross-scale experimental designs and platforms. Here, we present multiple examples on linking structural and functional ecosystem responses to threats, feedbacks between water and nutrient and/or carbon cycling with a focus on how novel interdisciplinary sensor platforms are ideal tools to improve our process understanding, by harnessing scientific and technical advances in several disciplines including in-situ stable isotope techniques, flux measurements, machine learning, or remote sensing.
 
Analysis of the Global Multi-GNSS Network Processing Raw Observation Approach using BeiDou
Authors: Dumitraschkewitz Patrick , Mayer-Guerr Torsten , Krauss Sandro , Oehlinger Felix , Suesser-Rechberger Barbara , Strasser Andreas , Tieber-Hubmann Cornelia
Published: March 2024

Global Navigation Satellite System (GNSS) products are an integral part of a wide range of scientific and commercial applications such as precise orbit determination for low Earth orbit satellites, earthquake monitoring, GNSS reflectometry, tropospheric and ionospheric research, surveying and many more. These products, consisting of GNSS orbits, clocks, phase biases and more, are generated by the International GNSS Service (IGS) analysis centres by processing observations from a global network of ground stations to one or more GNSS constellations. The processing consists of a combined station position and GNSS satellite orbit determination using a least squares approach donated as global multi-GNSS processing.Within the IGS 3rd reprocessing (repro3) campaign for the new release of the International Terrestrial Reference Frame (ITRF), Graz University of Technology (TUG), Working Group Satellite Geodesy has contributed as an Analysis Centre (AC) for global multi-GNSS processing. TUG has demonstrated high quality results on par with other ACs using its self-developed geodetic processing software Gravity Recovery Object Oriented Programming System (GROOPS). Within GROOPS the global multi-GNSS processing uses the raw observation approach. The raw observation approach uses all measurements as observed by the receivers without explicitly creating any linear combinations or differences. This allows the information contained in each individual observation to be fully exploited.GROOPS has been shown to be capable of global multi-GNSS processing using GPS, Galileo and GLONASS. With more publicly available metadata for the BeiDou system, GROOPS has been further developed to use BeiDou within global multi-GNSS processing using the raw observation approach. Therefore, in this contribution we present the improvements in GROOPS global multi-GNSS processing using BeiDou and discuss the quality of the resulting orbit, station position time series, clock and phase bias products.
Impact of Socio-Economic and Climatic Scenarios on Power Trade Vulnerability in Africa
Authors: Bonserio Teresa , Carlino Angelo , Giuliani Matteo , Castelletti Andrea Francesco
Published: March 2024

Energy security in Africa is seriously compromised by the continent's degree of political instability. Corruption, armed conflicts, and ineffective governmental institutions impede the maintenance of the existing energy infrastructure and deter new foreign investment. As a result, many African nations face unreliable power supplies, hampering economic growth. This effect, however, is usually overlooked in large-scale energy systems planning, which is often uniquely based on cost optimality considerations. This study aims to quantify the vulnerability of the cost-optimal African power systems and the potential power deficits arising from countries' political instability. To do so, we examine African countries' generation mixes and power trades over 2020-2050 using six scenarios obtained with the OSeMOSYS-TEMBA energy system model. The six scenarios harmonize assumptions regarding socio-economic development, land-use change, and climate change impact on water availability for hydropower using the SSP-RCP framework. Moreover, capacity factors for existing and planned hydropower projects are included, considering both median and very dry hydrological regimes.In each scenario, we assess the degree of power trade-related political risk at the continental and country scales. This measure expresses the vulnerability of international power trades according to the political instability of participating countries. The governance indicators, reflecting the countries' degree of political instability, are projected for each SSP until 2050. Moreover, we stochastically quantify the power deficits due to operational deviations from cost-optimal international power trades caused by countries' political instability.Our results show that countries representing hotspots of political risk are located in western, southern and central-eastern Africa. These results are aligned with those obtained from an evaluation of the ecosystem impact of hydropower projects in Africa. Moreover, scenarios with more ambitious climate policy show higher political risk, especially in southern Africa. Instead, very dry hydrology scenarios are associated with reduced risk in eastern Africa and increased risk in southern Africa. These results underscore a crucial need for stable governance frameworks and international cooperation to foster sustainable energy development in the region. Strategic interventions can indeed produce tangible impacts by reducing risks in the short term.