bluuebunny/crossref_metadata_2025 huggingface dataset:
Demonstrating the importance of streamflow observation uncertainty when evaluating and comparing hydrological models
Authors: Aerts Jerom , Hoch Jannis , Coxon Gemma , van de Giesen Nick , Hut Rolf
Published: February 2023

Large-sample hydrology datasets provide an excellent test-bed for evaluating and comparing hydrological models. The validity of the results from studies that use large-sample hydrology datasets, however, can be undermined when observation uncertainty is not taken into account in the analyses. The differences between model simulations might well be within the observation uncertainty bounds and are, therefore, inconclusive on model performance.To this end, we highlight the importance of including streamflow observation uncertainty when conducting hydrological evaluation and model comparison experiments based on the CAMELS-GB dataset (Coxon et al., 2015) . We introduce a generic flexible workflow that accounts for streamflow observation uncertainty, but is also applicable for other sources of observation uncertainty. This workflow is implemented in the ‘FAIR by design’ eWaterCycle platform (Hut et al., 2022). Two experiments are conducted to demonstrate the effect that streamflow observation uncertainty has on large-sample dataset based conclusions. The first experiment is an inter-model comparison experiment of the distributed PCR-GLOBWB and wflow_sbm hydrological models (Hoch et al. (2022) & van Verseveld et al. (2022)). The second experiment is an inner-model evaluation of the impact of additional streamflow based calibration on the results of the distributed wflow_sbm hydrological model. For the latter we found that approximately one third of the catchment simulations resulted in model differences that fell within the bounds of streamflow observation uncertainty.
Revealing controls on groundwater level patterns by backward variable elimination in the Baltic states
Authors: Bikše Jānis , Retike Inga , Haaf Ezra , Popovs Konrāds , Kalvāns Andis
Published: February 2023

Groundwater level data are often spatially and temporary unevenly distributed, and the heterogeneity of hydrogeological systems limit simple extrapolation to data-scarce locations. Here, similarity of hydrogeological systems can be used to transfer dynamics of groundwater levels from monitored to unmonitored locations. Therefore, the major controls of hydrogeological systems need to be investigated. This study aims to uncover dominant patterns of the groundwater levels and to connect them with possible controls or driving features (such as the catchment and topography characteristics, aquifer properties, climate and land use) of hydrogeological systems in the Baltic states. Part of the spatial features were calculated for three different buffer sizes (300m, 3km and 5km). Gapless daily groundwater hydrographs (prepared by Bikše et al., 2023) were used to create groundwater level patterns by clustering approach. Then, random forest classification was performed using a backward variable elimination approach to find the most significant site-descriptive features for each cluster. The results show that the most significant tend to be geological features in the well cross-section, followed by topographic features within the vicinity of the well. We also found that anthropogenic impacts can play a significant role and should be considered when analyzing groundwater level patterns.References:Bikše, J., Retike, I., Haaf, E., Kalvāns, A., 2023. Assessing automated gap imputation of regional scale groundwater level data sets with typical gap patterns. EarthArXiv. https://doi.org/10.31223/x5n94x "The study has been funded by Iceland, Liechtenstein and Norway through the EEA and Norway Grants Fund for Regional Cooperation project No.2018-1-0137 “EU-WATERRES: EU-integrated management system of cross-border groundwater resources and anthropogenic hazards" and by the Latvian Council of Science, project “Spatial and temporal prediction of groundwater drought with mixed models for multilayer sedimentary basin under climate change”, project No. lzp-2019/1-0165.
Coastal carbonate systems: evolving paleoclimatic and paleoenvironmental proxies to relative sea-level change
Authors: Forzese Martina , Maniscalco Rosanna , Nádudvari Ádám , Nürnberg Dirk , Speranza Fabio , Todrani Alessandro , Zimmermann Udo , Butler Robert WH
Published: February 2023

Ancient coastal carbonate depositional systems provide exceptional records of past changes in relative sea level– globally and locally (tectonics) – and of paleoenvironmental variations. Here we present new work on carbonate outcrops within the UNESCO Rocca di Cerere Geopark in central Sicily (Caltanissetta and Enna districts). They show superb sub-vertical cliffs made of Pleistocene packstones with clinoforms which provide a high-resolution record of relative sea-level changes that correlate with precession cycles. Regionally these successions deposited during Plio-Quaternary forced regression caused by late-orogenic uplift. However, their deposition within local thrust top basins was modulated by local uplift and tectonic tilting. Collectively these global, regional, and local processes are recorded by offlapping of successive depositional cycles. Moreover, the high-resolution photogrammetric surveys we developed, revealed that the underlying anticlines tilted the original beds of almost 20°. The packstones are derived from fauna: micro-habitat variations have been here traced by changes in sediment provenance, fossil assemblages, and preservation. The resultant stratal architectures reflect the interplay between the efficiency of this carbonate factory, the environmental conditions, the minute siliciclastic input, and the evolution of accommodation space. Bio- and magneto-stratigraphy were fundamental to date, the parasequences, while organic and inorganic chemistry, benthic foraminifera assemblages, as well as stable isotopes analyses (δ18O and δ13C) are used as environmental and climatic proxies (where possible) to reconstruct coastal dynamics (physical and biological), in relation to the tectonic history and sea-level change.These outcrops provide analogues to interpret stratal patterns in subsurface examples where these types of strata form important aquifers – and shallow gas reservoirs.
Cropland abandonment across the Yangtze River Basin does provide only limited benefits for C sequestration
Authors: Long Yuqiao , Sun Jing , Wellens Joost , Colinet Gilles , Wu Wenbin , Meersmans Jeroen
Published: February 2023

Recent estimates from satellite imageries indicated that extensive cropland abandonment took place across China due to rural outmigration, agricultural policy and environment changes[1-3]. Cropland abandonment provides an opportunity for C sequestration, and therefore climate change mitigation, soil retention and food security. However, this depends on the duration of cropland abandonment, which lacks comprehensive research. In this study, we map cropland abandonment and recultivation across the Yangtze River Basin in central China using a series of annual land cover maps of the period 2000 - 2020. The InVEST model is used to study the spatial distribution of carbon storage. We found that cropland abandonment is widespread, but last on average only 5.5 years. In addition, over 50% of the abandoned croplands will be recultivated (i.e. back into cropland) or convert into impervious surfaces (i.e. urban) within 20 years, limiting its ability to provide ecosystem services, such as climate regulation, soil retention and food security, due to a relatively small capacity of C sequestration. More precisely, the combined effect of recultivation and conversion into impervious surfaces resulted in an accumulated loss of 75% of abandoned croplands and 41% of carbon as compared to a situation without recultivation or conversion into impervious surfaces. In conclusion, this study highlights the need for land policymakers to make careful reflections as regards the conversion of abandoned croplands in order to mitigate climate change and combat soil degradation. Hence, it could be interesting to set up incentives for ecological restoration in order to valorize opportunities that cropland abandonment may provide us with when aiming to achieve the UN Sustainable Development Goals (SDGs). References:1. Liang, X.; Jin, X.; Yang, X.; Xu, W.; Lin, J.; Zhou, Y. Exploring cultivated land evolution in mountainous areas of Southwest China, an empirical study of developments since the 1980s. Land Degradation & Development 2021, 32, 546-558.2. Long, Y.; Wu, W.; Wellens, J.; Colinet, G.; Meersmans, J. An In-Depth Assessment of the Drivers Changing China’s Crop Production Using an LMDI Decomposition Approach. Remote Sensing 2022, 14, 6399.3. Yan, J.; Yang, Z.; Li, Z.; Li, X.; Xin, L.; Sun, L. Drivers of cropland abandonment in mountainous areas: A household decision model on farming scale in Southwest China. Land Use Policy 2016, 57, 459-469.
The role of lignin in the saprotrophic degradation of plant biomass in boreal forest soil.
Authors: Thirunavukkarasu Aswin , Öquist Mats , Schleucher Jurgen , Sparrman Tobias , Hedenstrom Mattias , Nilsson Mats , Bertilsson Stefan
Published: February 2023

The amount of carbon stored in boreal forests soil as Soil organic matter (SOM) is significant. Carbohydrate polymers such as cellulose and hemicellulose constitute 40-50% of the SOM mass in the surface mor layer, even in SOM that has been decomposed for decades to centuries. This is in contrast to conceptual decomposition models assuming aromatic and aliphatic polymers to constitute the fraction of recalcitrant SOM. One prevailing view for support is that lignin manifest itself as a factor in the stabilization of carbohydrate polymers as SOM. However, detailed elucidation of how the complex array of molecular moieties making up SOM decompose over time is lacking. Here we investigated the effect of lignin content and composition during the progressive degradation of polymeric carbohydrates, lignin, and lipids in the lab during a year-long soil decomposition study using Aspen (Populus tremula) wood as a model substrate. To specifically address lignin decomposition we used a range of Aspen clones that varied naturally in their lignin content (high lignin 30% - low lignin 25%) with boreal coniferous forest soil obtained from the surface moor layer (O-horizon). The decomposition of the different molecular moieties of the model substrate was evaluated by Two-dimensional (2D) liquid state 1H–13C nuclear magnetic resonance (NMR) spectroscopy. In addition, the CO2 production during decomposition was monitored continuously and assays for exo-enzymatic activity was carried out at selected time points.The NMR spectroscopy revealed that for different periods of decomposition, saprotrophic microorganisms preferred different monomers of polymeric lignin, carbohydrates, and lipids. The relative degradation of resinol, spirodienone, and cinnamyl alcohol were higher among lignin interlinkages and the relative degradation of p-hydroxybenzoate and syringyl were higher among lignin subunits. For carbohydrates, the relative degradation of mannose and glucose were higher than that of e.g. xylose. The relative degradation of unsaturated fatty acids was higher among lipids. The lignin: carbohydrates ratio decreased linearly over the period of decomposition. This showed that the initial degradation of lignin compounds was greater compared to the decomposition of carbohydrate compounds. The significant difference in the relative degradation of mannose among model substrate with different lignin content showed that lignin had no effect on cellulose degradation but may have had an effect on the preferential degradation of hemicelluloses. The high-resolution decomposition patterns we observe are crucial for obtaining a detailed mechanistic understanding of plant polymer decomposition by soil microorganisms during the initial stages of SOM genesis. Keywords: Soil organic matter (SOM), Lignin, Carbohydrates, 2D NMR, Decomposition
Subsurface stormflow source area identification using depth profiles of the water-soluble organic matter
Authors: Fasching Christina , Chifflard Peter
Published: February 2023

Hydrological dynamics of hillslopes, particularly subsurface stormflow (SSF), are highly complex and variable in space and time. Frequently, available studies are often limited to single slopes or few storm events. As a result, the transfer of these findings to other slopes or catchments is associated with great uncertainties. Thus, for upscaling and model validation, a quantification of the hydrological dynamics of hillslopes and the factors influencing the spatial and temporal patterns of subsurface stormflow is urgently needed. Closely related to the hydrological dynamics of hillslopes is the export of organic carbon from the soils to the adjacent stream. However, the spatial sources of carbon are still largely unclear because the exact flow paths of SSF within the slope are not well known. In order to address this knowledge gap, we took a hydro-biogeochemical approach, that measures the water-soluble organic matter (WSOM; concentration, absorbance and fluorescence) along 480 locations on 100 hillslopes, in four contrasting catchments – varying from low to high mountain ranges (Sauerland, Ore Mountains, Black Forest, Alps). This enables us to derive empirical relations among different landforms (i.e., convergent, divergent and planar slope shapes, flow path lengths and valley shapes), bedrock and soil properties, and to quantify the spatial variability and stability of subsurface hydrological process patterns (e.g., flow directions, transit times, hydrochemical and biochemical composition). Distributed sampling of WSOM along the soil profile (6 WSOM samples per profile; both during wet and dry conditions) will help to assess the vertical and lateral subsurface flowpaths of water in the unsaturated and saturated zone, and the spatial discretization of source areas for SSF. We will use an array of state-of-the-art laboratory equipment and methods (TOC-Analyzer, Fluorescence Spectrometry) to analyze WSOM. First results will show depth profiles of WSOM in the four contrasting catchments from the low to high mountain ranges (Sauerland, Ore Mountains, Black Forest, Alps). By these depth profiles source areas of SSF can be detected.
Do mangroves act as a secondary source of plastic during extreme events?
Authors: Reed Bradley , Robins Peter , Demmer Jonathan , Neill Simon
Published: February 2023

Marine plastic pollution is one of the most visible environmental problems in and around the coastal regions of South East Asia. To fully address the marine plastic pollution problem, there must be a source-to-sink approach, reducing litter at each stage of its pathway to the open ocean. Mangroves are an important and widespread ecosystem in South East Asia on the interface between terrestrial and marine environments, and a key habitat and nursery for a number of species. Mangroves have also been reported to trap plastic litter, potentially acting as secondary sources to coastal marine environments. The Philippines are particularly vulnerable to compound hydrological events due to the seasonal monsoon and typhoons which regularly cross the region. South East Asia is a complex region oceanographically and hydrologically with high loads of plastic litter being exported into the regional seas. To correctly estimate local plastic pollution budgets and understand the transboundary movement of plastic from land to sea, modelling studies must account for the different environmental drivers and strong seasonality of the region. Here, we present preliminary results of a modelling study investigating the impact of Typhoon Rai on the retention and contribution of plastic litter by mangrove ecosystems of Cebu Island, the Philippines. The results of a three-dimensional, hydrodynamic model (ROMS) with wind, tidal and wave forcing will be presented. Future plans to apply a Lagrangian particle tracking model informed by in-situ measurements to investigate the behaviour of plastic litter within this typhoon weather system will also be outlined. This will help to understand how plastic litter is retained or exported during extreme events around Cebu Island and assess the likelihood of mangroves to act like a temporary sink or secondary source during extreme and mean events. Understanding the role of mangroves under different environmental conditions could clarify another step in the source-pathway-sink model of plastic litter in the region. 
Thermal profiling to quantify the spatial variability of ambient groundwater flow at a provisional groundwater abstraction site
Authors: Bense Victor , Nie Luka , Oosterwijk Jacob
Published: February 2023

Knowledge of the saturated hydraulic conductivities of aquitards in provisional groundwater abstraction sites is essential to assess the sustainability of future water production. The subsurface of the site in the southwest of The Netherlands has a simple layer cake stratigraphy. Temperature-depth profiles in 12 boreholes were measured and analysed to infer vertical fluxes across an aquitard at a depth (~100 m) below where the impact of recent surface warming could be detected. Hence, the analytical mathematical solution for coupled groundwater-heat flow described by Bredehoeft & Papadopulos in 1965 could be be employed for this purpose. The selection of the depth interval for the aquitard for which the solution is applied, is guided by scanning through the TDP to find depth-intervals for which both a low RMSE between observed temperature and solution is obtained as well as a high Peclet number indicative of significant vertical groundwater flow. Through comparison of the depth intervals with lithological data, temperature-depth profiling is shown to have the capacity to detect aquitards, provided that the approximate depth of the aquitard is known, as well as the flux direction and magnitude across the aquitard. In combination with observed hydraulic gradients, the spatial variability of hydraulic conductivity of the aquitard could be evaluated. These values range from 10 to 100 mm/d, where earlier estimated values using more traditional methods suggested a range of  5 to 10 mm/d.
Accounting for Seasonal Soil Moisture Retrieval Errors in the Generation of Climate Data Records
Authors: Stradiotti Pietro , Gruber Alexander , Preimesberger Wolfgang , Madelon Rémi , van der Schalie Robin , Rodriguez-Fernandez Nemesio , Hirschi Martin , Dorigo Wouter , Kidd Richard , Albergel Clément
Published: February 2023

Multi-decadal climate data records of soil moisture (SM) are generated by merging distinct satellite microwave remote sensing data sets to serve countless Earth System applications. Such products generally outperform the individual sensor records as they provide a least squares solution to the merging of SM. Within the well known European Space Agency's (ESA) Climate Change Initiative (CCI) for SM product, it was demonstrated that a performance leap is achieved by informing the averaging of multiple retrievals with Triple Collocation Analysis (TCA)-based uncertainty estimates of the input data sets. However, while the approach taken to generate the ESA CCI SM product assumes a constant random error variance for an entire sensor period, it has become evident that errors in SM remote sensing retrievals fluctuate throughout the year. This has been linked to the fact that environmental parameters---foremost vegetative growth---are characterized by a seasonality, such that their impact on the SM retrieval varies with the same cycle. Therefore, taking this seasonal component into account in the least squares formulation of the merging problem is a logical next step. This study examines whether a seasonal adaptation of TCA leads to a performance improvement in the merging, using input data from the ASCAT, AMSR2, and SMAP missions and the GLDAS2.1 model as a climatology baseline. The two key findings are that i) since seasonal uncertainty variations affect all sensors in a similar way, they cause only marginal changes in their relative weighting, which leads to the merged SM estimates not changing significantly from the static to the seasonal merging; yet ii) an evaluation against in situ data suggests that the estimated uncertainties of the new merged product are more representative of their actual seasonal behavior. Such improved uncertainty representation is potentially beneficial to various applications, for instance in the weighting of SM observations for assimilation in physical models. Based on these findings, we conclude that using a dynamic TCA approach can add value to merged products such as the ESA CCI SM by providing a more realistic characterization of data set uncertainty---in particular its temporal variation.
Global projection of potential effects of future air quality on bee visual navigation
Authors: Cho Yoori , Jeong Sujong , Chang Dong Yeong
Published: February 2023

Airborne aerosols can alter incoming solar radiation inducing different radiative responses, yet the potential ecological effects of changes in the degree of linear polarization (DoLP) by the light alteration remain largely unknown. Light polarization is an important navigational cue for honeybee for which a threshold intensity (i.e., the DoLP) for a reliable response is known as 15%. Here, we quantify the relationship between the mass concentration of airborne fine particulate matter (PM2.5) and the DoLP by ground-based observation to provide an estimate of how the quantity of PM2.5 changes the DoLP in general and how these changes will impair navigation of honeybee by limited-visibility at the global level. We find that the PM2.5 mass concentration exponentially decreases the DoLP, reducing the average and maximum DoLP, and the size of area containing perceivable polarization information by honeybee over the sky. Applying these results to global air quality prediction models, EMAC, MPI-ESM1.2-HAM, MIROC-ES2 under a BaU (for EMAC) and SSP370 (for MPI-ESM1.2-HAM, MIROC-ES2L) scenario, we find that projected areas and the number of days of limited-visibility that honeybee experience increases globally on average. Our estimates capture almost year-round risk hotspots of limited-visibility over sub-Saharan Africa, Eastern Mediterranean, Southeast Asian regions in 2050. In particular, India is projected to experience approximately a 10 folds increase in the number of days of limited visibility. Developing countries are more vulnerable to degrading air quality than developed countries in terms of limited-visibility for honey bees. Overall, our study demonstrates degrading air quality in 2050 as a result of business-as-usual emissions of air pollutants can affect bee navigation, threatening fundamental plant-pollinator interactions. Further, warming climate will exacerbate this impact.This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. RS-2022-00155875).
Numerical investigations of change in hydrodynamics of a coastal aquifer due to saline groundwater pumping
Authors: Narayanan Dhanya , t i Eldho
Published: February 2023

Coastal communities in dry and semiarid areas confront a severe scarcity of potable water. To meet the requirements of a growing population by increased inland groundwater pumping, led to saltwater intrusion, which eventually rendered the available water unfit for human use. According to studies, desalination plants using saline groundwater as feed water (subsurface intake) might alleviate the problems with coastal water supply and quality. In this context, it becomes imperative to understand the saltwater transport and the associated flow and mixing process when saline groundwater is pumped from beneath the freshwater-saltwater interface. Hence to ascertain the effect of saline groundwater pumping on the hydrodynamics, a standard test aquifer was simulated using the finite difference model SEAWAT. The hydrodynamics is quantified by the entrained saltwater which will influence width of mixing zone, length of intrusion of toe and discharge of Darcy flux back to sea. Entrained water is the amount of saltwater entrained through freshwater - saltwater transition zone, for a steady and stable (lighter freshwater above heavier saltwater) flow system in an aquifer. Performance analysis were carried out to infer the influence of pumping rates on the velocity of entrainment. The results indicate that the mixing zone changed from having a sloping shape to one that was partly vertical and partially sloping, resulting in the establishment of a mixed water interface adjacent to the saline groundwater well. It is likely that there exist modest density gradients between the two fluids, but they quickly attained equilibrium due to the localized velocity change that was observed. Pumping induced more saltwater into the aquifer, which get pumped out restricting the further inland invasion of wedge. Understanding this interaction is crucial in order to determine the method's mitigation potential prior to adopting subsurface input for desalination.   
Comparison of the Life Cycle Analysis of inert electrodes and the Hall-Heroult process in aluminum production
Authors: Bronkema Bethany , Sævarsdóttir Gudrún , Finger David C.
Published: February 2023

Comparison of the Life Cycle Analysis of inert electrodes and the Hall-Heroult process in aluminum production Bethany Bronkema bethanyb@ru.is Guðrún Arnbjörg Sævarsdóttir gudrunsa@ru.isDavid C. Finger davidf@ru.is To be presented orally at EGU2023 – April 23rd-28th.Reykjavik University, School of Science and Engineering, Department of Engineering, Reykjavik, Iceland
 The global production of pure aluminum consumes substantial amounts of energy and alone produces around 1.1 billion metric tonnes of carbon dioxide emissions (CO2, eq) each year, or around two percent of global emissions. The Hall-Heroult process is currently the only industrial process for primary aluminum production, producing up to two tonnes of CO2 per tonne of pure aluminum by electrolysis in a molten salt electrolyte using carbon anodes. However, the use of inert electrodes represents a low-carbon alternative to the Hall-Heroult process as direct emissions can be significantly reduced, lowering the CO2, eq footprint and the ecotoxicity of aluminum production. However, a transition to inert anodes implies a redesign of current electrolysis cells to optimize the energy requirement of the new process. In this study, we performed a life cycle analysis to compare the ecological footprint of the aluminum production process with inert electrodes and the Hall-Heroult process. The life cycle assessment was conducted using GaBi software linked to the ecoinvent database and complemented with primary data. We calculated the ecological footprint for five scenarios: i) using inert electrodes with a 13.5 kWh per kilogram of aluminum energy requirement, ii) using a 17 kWh per kilogram of aluminum energy requirement, iii) using Icelandic grid electricity (primarily renewable hydropower), iv) using a global energy mix (primarily based on fossil energy), and v) and “best case scenario” in which a renewable source of energy is assumed for the refinement stage preceding the smelting stage. Each of these scenarios were then compared with the ecological footprint for the Hall-Heroult process using carbon anodes. The preliminary results reveal that the energy mix always has the highest impact on the ecological footprint in the earlier refinement and electrolysis stages. However, using inert electrodes in smelters powered with renewable electricity can significantly lower the carbon footprint and ecotoxicity of aluminum production.
Ground-based Radar baseline correction based on the DEM model
Authors: Zhang Zeyu , Ding Xiaoli , Wu Songbo , Zhao Junhong
Published: February 2023

In recent years, ground-based radar has been widely used as an emerging deformation monitoring technology. Compared with traditional satellite-based radar, ground-based radar has many unique advantages, such as high temporal resolution and independence from atmospheric and ionospheric influences. Scholars usually assume that the radar's position is fixed every day when making continuous observations of the target area for multiple days. However, when experimental conditions do not allow us to temporarily fix the radar on the ground, a baseline error arises between two days of measurements, which causes the attitude of the radar to change. Based on the upper and lower dual antenna design adopted by the GAMMA portable Radar, this paper proposes a DEM model generated using the upper and lower antennas to back-calculate the baseline difference between the two measurements and eliminate the baseline difference by the model to ensure the accuracy of the experimental results. The results of the measured data processing demonstrate the effectiveness of the method mentioned in this paper in eliminating baseline errors
The 3D stress field of Nordland, northern Norway - insights from numerical modelling
Authors: Gradmann Sofie , Keiding Marie , Olesen Odleiv , Maystrenko Yuriy
Published: February 2023

The Nordland area in NW Norway is one of the tectonically most active areas in Fennoscandia. It exhibits patterns of extension, which are in contradiction to the first-order regional stress pattern that reflects compression from ridge-push. The regional stress field stems from the interaction of ridge push and GIA (glacial isostatic adjustment); the local stress field mainly results from gravitational stresses, as well as the flexural effects of sediment erosion and re-deposition.We develop 3D finite element numerical models of crustal scale, using existing geometric constraints from previous geophysical studies. Internal body forces, induced by variations in density, topography or Moho depth, already yield significant deviatoric stresses, which are often omitted in stress models. We show that these can strongly influence the near-surface stress regime, in particular for the continental-margin setting we are considering. Similarly, existing weakness zones (such as faults) control the local stress field.We apply the far-field stress fields (GIA, ridge-push, sediment redistribution) as effective force boundary conditions to the sides or base of the model. This way, we can account for all stress sources at once, but can also vary them separately in order to examine their relative contributions to the observed stress and strain rate fields.We compare our models to the stress and strain observations derived from different recent seismological and geodetic data sets. These point to a correlation of seismicity with major changes in the crustal geometry.
Optimisation of the water and climate science, policy and practice nexus: Insights from the AfriAlliance knowledge brokerage events.
Authors: Kileshye Onema Jean-Marie , wehn Uta , Tlhagale Mamohloding , Sossou Seyram , Quayle Tarryn
Published: February 2023

Over a five year period, a systemic approach to water and climate solutions refer to as social innovation was developed in the framework of the AfriAlliance project. The approach recognised the need to combine five aspects for increased relevance and synergies for the water and climate science, policy and practices. The above mentioned aspects included technological solutions, governance structures, capacity development, a business roadmap and knowledge brokerage events. This manuscript documents lessons learned from the fifteen knowledge brokerage events held across the African Continent.  These events provided a platform to 1060 participants who came across 125 innovations. Policy makers, funders, utility operators, scientists, non-governmental organisations, river’s authorities and organisations, entrepreneurs and practioners were represented. The AfriAlliance knowledge brokerage events covered all the 5 African sub-regions. These events were designed and implemented in an innovative way providing participants ample opportunity to network and engage with innovators after their pitch presentations. Specialised and high-level panels provided policy makers, funders and international cooperating partners an opportunity to share their perspectives with innovators and the audience. Policy makers recurrently indicated the need to align water and climate innovations and solutions to existing priorities and frameworks. Funders and international cooperating partners highlighted the limited capacity from innovators in terms of scalability and access to funding. These events also brought up the difficulty of always getting the right audience especially when the knowledge brokerage event took place in the framework of specialized conferences. The Covid-19 pandemic introduced also an additional layer of complexity and required some adaptation to the face to face set-up that was initially designed. Hence two out of the fifteen events took place online. The virtual setup appeared to reach a broader geographical audience but the interactions were not as effective as those organised in person.  These events have shown a considerable potential to bring together scientists, policy makers and practioners in order to match topical solution providers and the users. On the other hand, these kind of knowledge brokerage events remain project dependent and adhoc in nature for one to expect some long-term impact.
On the Evapotranspiration estimates of two contrasting and Heterogenous Ecosystems in Sardinia
Authors: Corona Roberto , Sirigu Serena , Montaldo Nicola , Katul Gabriel G.
Published: February 2023

Sardinia island is a reference for ecohydrological studies on past and future climate change effects, representing typical conditions of the western Mediterranean Sea basin. Ecosystems are heterogenous, and trees optimize the use of water through the root systems, uptaking water from the deep layers.
Two micrometeorological towers have been installed in two different sites under different precipitation conditions. The first is installed in Orroli (annual precipitation of about 600 mm), in a patchy mixture of wild olive trees and C3 herbaceous that grow in a shallow under a rocky layer of basalt, partially fractured (soil depth 15 40 cm), with a tree cover percentage of 33% in the footprint. Instead, the second is in a mountainous forest site of Quercus ilex characterized by steeper slopes and rocky outcrops (mean annual precipitation of about 800 mm), and tree cover percentage of 68% in the footprint. In both sites land surface fluxes and CO2 fluxes are estimated using the eddy correlation technique while soil moisture was estimated with water content reflectometers, and periodically leaf area index (LAI) were estimated.
The following objectives are addressed:1) pointing out the dynamics of land surface fluxes, soil moisture and CO2 for two contrasting sites; 2) assess the impact of vegetation dynamics and type on the CO2 and water balance dynamics; 3) evaluate the soil effect on water and energy budgets.
The Orroli site is more controlled by rainfall seasonality, and vegetation species use the source of water stored in the deep rocky layer to sustain their physiological activity. In the Orroli site we found seasonal dynamics in the CO2 flux and in the evapotranspiration (ET) terms, which are higher when grass and woody vegetation species are present and lower when the grass component dies. Instead, we found a constant flux of ET in the Marganai highlighting the high efficiency of tree species in extract the deep sources of water. ET is higher in the Orroli site if the grass species are present in live form, and then LE is higher in the Marganai forest. The ET of Quercus ilex in the Marganai forest seems being not controlled by surface soil moisture, because the annual precipitation is enough for sustain the transpiration needs of that fraction of tree cover. The results confirm a threshold of 700 mm/year of rain, below which rain can restrict tree cover growth.
More realistic CO2 fertilisation in a revised big-leaf model
Authors: Jones Simon , Cox Peter
Published: February 2023

The observed increase in forest productivity over the industrial period is largely attributed to a stimulation of photosynthesis by increasing atmospheric CO2 concentrations. The extent to which this fertilisation effect will persist in the future, however, is uncertain as competing limitations such as the availability of nutrients and soil moisture may prevent plants from making use of the carbon they assimilate, which may dominate the future photosynthesis response.Many early studies of the CO2 fertilisation effect use simulations that make use of the classical ‘big-leaf’ approach for scaling leaf photosynthesis to the canopy described by Sellers et al., (1992), which has been shown to produce unrealistically low sensitivities to light. Light limitation has the potential to significantly weaken the CO2 fertilisation effect relative to these early predictions. More realistic multi-layer canopy schemes have since been developed that produce more accurate light responses, however, the impact that this has on predicted CO2 fertilisation seems to have gone unstudied.In this presentation we present a modified version of the big-leaf canopy scheme. This new version produces more realistic sensitivities to light while remaining more computationally efficient than modern multi-layer canopy schemes. We examine the effect that the new big-leaf scheme has on predictions of future CO2 fertilisation and demonstrate the importance of correctly simulating the dominant limitations of photosynthesis.
Global impact on aerosol characteristics during COVID-19 using ground- and satellite-based observations
Authors: Ansari Kamran , Srikanthan Ramachandran
Published: February 2023

Corona Virus Disease 2019 (COVID-19) caused global reductions in transportation and industrial activities, which provided an unprecedented opportunity to examine the effects of reductions in anthropogenic activities on aerosol characteristics on a global scale. The observational study of the impact on columnar aerosol characteristics and radiative effects during the COVID-19 pandemic outbreak period, when anthropogenic emissions are significantly suppressed globally, can be helpful in quantifying the anthropogenic influence on aerosol properties for the accurate assessment of radiative and climatic impacts of aerosols. This study utilizes the high-quality aerosol datasets from Aerosol Robotic Network (AERONET) over 224 sites covering the entire globe, and satellite-based Moderate Resolution Imaging Spectroradiometer (MODIS) retrieved aerosol optical depth (AOD) to analyze the difference in columnar aerosol properties between the year 2020 (COVID) and 2017-2019 (normal) on a seasonal scale over 10 different regions of the world. The most significant reduction in AOD by AERONET and MODIS observations is observed over most of the regions during the summer season, followed by the spring season of 2020 compared to the respective seasons of 2017-2019, when many countries imposed lockdowns. During summer, the highest reduction in AOD is observed over South Asia by MODIS (−0.09, 20% reduction) and AERONET (−0.07, 15% reduction), where aerosol loading is relatively higher during normal scenario. Over East North America and Europe, AERONET AOD reduced by −0.02 and −0.04, respectively. A significant reduction in Angstrom exponent (AE) and fine mode fraction (FMF) in most regions confirms the reduction in fine mode anthropogenic aerosols. However, a significant increase in AE and FMF (~20%) in South Asia is observed due to significant reduction in dust AOD (natural), which decreased the amount of coarse mode aerosols during the COVID period. Furthermore, the difference in aerosol radiative forcing at the surface (ARFSFC) by Clouds and Earth’s Radiant Energy Budget Scanner (CERES) data shows a significant reduction in ARFSFC in most regions during COVID period, whereas the highest reduction in ARFSFC of ~20% is observed over South Asia consistent with the reduction in aerosol emissions. This observational study over a global scale during the unprecedented COVID-19 period can be helpful for undertaking future mitigation strategies related to anthropogenic aerosol emissions and their precursors to reduce their impact on the climate.
Current status and future perspectives of VLBI global solutions
Authors: Kern Lisa , Krasna Hana , Böhm Johannes , Madzak Matthias
Published: February 2023

The realization of a terrestrial and celestial reference frame is a fundamental requirement for all ground- and space-based observations, making the interpretation of key global processes on Earth possible and therefore contributing to a better understanding of the Earth system. In this matter, the space-geodetic technique called Very Long Baseline Interferometry (VLBI) provides the perfect link between stations on the Earth's surface and extragalactic sources with a quasi-fixed position. In the process of an intra-technique combination, it is possible to estimate parameters that are common to all VLBI sessions in a common least squares adjustment, resulting in, e.g., catalogs of station and source positions (and station velocities) at a certain reference epoch. We present the current status of our new state-of-the-art and stand-alone Python software for the combination of VLBI sessions developed at the VLBI Analysis Center in Vienna. The combination process is based on homogenized, datum-free normal equations from SINEX (solution independent exchange format) files. In the future, we are planning on implementing filter solutions to ensure an optimal state estimation of the dynamical system Earth and further expanding the capabilities of our software by, e.g., allowing a combined analysis of different space-geodetic techniques (inter-technique combination) to further improve the consistency and accuracy of the resulting reference frames and Earth Rotation Parameters (ERPs). 
The Relationship Between Isolated Deep Convection Initiation and Topography in the North China Area
Authors: Lu Guilin , Ren Yangze , Fu Shizuo , Xue Huiwen
Published: February 2023

The characteristics of isolated deep convection initiation (DCI) and its relation to topography in the North China area are studies statistically and numerically. The infrared brightness temperature data from satellite Himawari-8 are utilized to identify DCI events in three summers. A total of 2534 DCI events are obtained and their locations show clustering over mountains and hills, suggesting the significance of local topography. Topography is described with elevation and relief amplitude. DCI events and grid boxes are counted. DCI events per grid box increases with elevation and relief amplitude. Among different types of topography, DCI is favored in mountains and hilly areas. Moreover, the morning cloud cover condition also shows notable impact on the relation of DCI and topography. For the regime characterized with less morning clouds (regime one), DCI strongly depends on elevation and relief amplitude, while for the regime with more morning clouds (regime two), topography shows a moderate impact on DCI. The time of DCI events are also recorded, and regime one shows a stronger diurnal variation and a peak occurring 2 hours earlier than that of regime two. The synoptic patterns show the difference of large-scale environment between the two regimes, which can explain their differences in DCI to some extent. To clarify the mechanism of topographic effect in DCI process, quasi-idealized numerical simulation in North China is conducted with WRF. The averaged 6-hourly ERA-Interim reanalysis data, which can maintain the major patterns of large-scale circulations, are inputted into the model as initial and boundary conditions. The elevation and relief amplitude of the study domain is varied in the model. The preliminary result shows that the speed of upscale convection growth changes with elevation and relief amplitude, which indicates that mechanisms involving topography-induced variation of solar heating may exist and need further numerical study. We suggest that special attention should be paid to elevation and relief amplitude (or topography type), as well as morning cloud cover condition when forecasting DCI in the North China area and mountainous areas around the world.
Turbulent Mixing in the Slupsk Furrow (Southern Baltic): Microstructure observations in 2019-2022.
Authors: Bulczak Anna , Rak Daniel , Walczowski Waldemar
Published: February 2023

The Slupsk Furrow, located on the main pathway of the inflow waters from the North Sea, is of key importance for the Baltic circulation and ecosystem. The dynamics of the Slupsk Furrow make it one of the principal areas of intensive mixing and transformation of deep waters on their way futher east. Internal waves and mesoscale eddies are dominant features of the water transport through the channel. We present a summary of the measurements collected in the Slupsk Furrow in 2019-2022 focusing on the microstructure measurements collected every 5-10 nm during three cruises of rv Oceania through the central channel and at two stations located on the southern topographic slope. Microstructure observations were collected using a free falling Vertical Microstructure Profiler (VMP) 250 of Rockland Scientific equipped with two shear, one micro-conductivity, one micro-temperature and a standard CTD (64 Hz) sensors. In total, 170 microstructure profiles (34hr) were collected in November 2020, 109 profiles (18 hr) in May 2021 at the station to the east of the Slupsk Sill and 354 profiles were collected in December 2021 (14 hr) and March 2012 (156 hr) at the southern topographic slope of the channel. The spatial and temporal variability of mixing intensity is presented and discussed. This research was financed by the National Science Centre (NCN) Poland, grant no. 2019/33/B/ST10/02189: “Turbulent mixing in the Slupsk Furrow (Southern Baltic)” project.