bluuebunny/crossref_metadata_2025 huggingface dataset:
Atmospheric and soil water stress on ecosystem carbon and water use during flash droughts
Authors: Xi Xiazhen , Yuan Xing
Published: February 2023

The combination of flash droughts and high temperature may have a significant effect on the ecosystem because of the soil and atmospheric moisture deficits. However, the stress of soil and atmospheric moisture deficits on carbon and water use of the ecosystem during flash droughts, particularly during the drought periods with hot conditions, are unclear over a large region. In this study, we decoupled the atmospheric and soil water stress over eastern China by using vegetation remote sensing products during flash droughts and their sub-periods that are accompanied by high temperature and intense radiation. The results showed that soil moisture (SM) stress on gross primary productivity (GPP) was significantly greater than the vapor pressure deficit (VPD) stress over eastern China, especially in humid area. In contrast, the atmospheric water stress in the North China Plain was more significant. By excluding the radiation effect, high VPD dominated the water stress on light use efficiency (LUE) in over 55% of the areas during flash droughts. For the hot periods of flash droughts, the GPP subject to VPD stress increased from 8% to 36% of the areas, especially in semi-arid and semi-humid regions. The concurrent hot and drought conditions also increased water use efficiency (WUE) for most areas. Moreover, the effect of water stress on LUE and WUE was similar to that during flash droughts. The reason may be that during hot periods of flash drought, the rise in VPD led to a decrease in vegetation stomatal conductance, which further reduced GPP, photosynthetically active radiation absorbed by vegetation and evapotranspiration at the similar rate.
Archimedean Spiral Distribution of Electrons in Earth Inner Magnetosphere
Authors: Sun Weiqin , Yang Jian , Wang Wenrui , Cui Jun
Published: February 2023

We present an analytic theory to demonstrate that electrons with an initially asymmetric spatial distribution would form an Archimedean spiral distribution in the inner magnetosphere. Such evolution is a result of the gradient/curvature drift, whose angular velocity decreases with radial distance. It has been known for a long time that spectrograms of energetic electrons in Earth's inner radiation belt exhibit time-varying organized peaks and valleys. Recent observations from Van Allen Probes have shown that such regular patterns are ubiquitous and are referred to as “zebra stripes”. Our theory can predict zebra stripes accurately. We also use the Rice Convection Model (RCM) to simulate zebra stripes. For the simplest situation with the dipolar magnetic field model, the analytic theory perfectly matches with the RCM simulation. In a realistic simulation, the RCM reproduces the time-dependent structures and evolution of the zebra stripes, which are in good consistency with Van Allen Probes observations.
Drought resistance enhanced by tree species diversity in global forests
Authors: Liu Dan , Wang Tao , Peñuelas Josep , Piao Shilong
Published: February 2023

Restoring species diversity is proposed as a strategy to improve ecosystem resistance to extreme droughts, but the impact of species diversity on resistance has not been evaluated across global forests. Here we compile a database that contains tree species richness from more than 0.7 million forest plots and satellite-based estimation of drought resistance. Using this database, we provide a spatially explicit map of species diversity effect on drought resistance. We found that higher species diversity could notably enhance drought resistance in about half of global forests but was spatially highly variable. Drought regimes (frequency and intensity) and climatic water deficit were important determinants of differences in the extent that species diversity could enhance forest drought resistance among regions, with such benefits being larger in dry and drought-prone forests. According to a predictive model of species diversity effect, the conversion of current monoculture to mixed-species tree plantations could improve drought resistance, with the large increase in dry forests. Our findings provide evidence that species diversity could buffer global forests against droughts. Restoration of species diversity could then be an effective way to mitigate the impact of extreme droughts on large scales, especially in dry and drought-prone regions.
Analysing Trade-Offs between Safety from Tsunamis Risk and Views of Ocean Water Using an Optimal Residential Area Model
Authors: Nakai Fuko , Uchiuzo Tatsuya , Okubo Kazuaki , Hideshima Eizo
Published: February 2023

Disaster risk reduction has become an increasingly prominent concern in urban planning due to recent catastrophic disasters such as the Great East Japan Earthquake in 2011. Building levees or relocating to higher ground are measures used to reduce the risk of tsunamis. However, if those measures are implemented too extensively, they may obstruct views of coastal water that benefit residents. Environments where residents can visually access the waterfront are crucial for promoting awareness of river and disaster risk reduction and repairing the way we interact with nature. However, in Japan, safety has frequently been prioritized by ignoring the views of coastal water that may be lost.This study developed an optimal residential area model for analysing the trade-offs between safety from tsunamis and views of coastal water (hereafter, ocean views), which will be able to support detailed urban planning. The model comprises weighted multicriteria, that is, the total tsunami risk and ocean views with controlling optimal allocations of population. Here we optimized “Improved Potential Achievement (IPA).” This indicated the extent to which the respective optimal value achieved has been achieved against the value (improved potential) of the two objectives being optimized alone as a baseline. We used the viewshed analysis to quantify ocean views. The analysis used the elevation value of each cell of the digital elevation model (DEM) to determine the visibility of a particular point of the ocean from a specific residential mesh. Using the visibility between specific locations, we conceptualized the index of “the ocean view presence” and “the width of the ocean view”. The ocean view presence expresses how many locations in a particular residential mesh have an ocean view. Meanwhile, the width of the ocean view expresses whether people have a panoramic view of the open ocean or whether they can only see a small area of ocean. We quantified ocean views using these indices.We applied the model to Kuroshio, a tsunami-prone area along the Nankai Trough in Japan and the optimal residential area is calculated for each 500-meter mesh. The results of the sensitivity analysis that changed the weight β (0<β<1) of the safety from tsunami criteria showed trade-offs in which the more safety from tsunami risk is weighted, the more the view of ocean water in the target area is reduced. If weight β is larger than 0.7, ocean views decreases steadily. This is a case study of a specific area and such results are not spatially consistent in all areas. However, similar trade-offs are likely to be obtained in areas with the ocean and mountains in close proximity. This analytical technique is likely to be useful in pre-disaster recovery planning that explores induction-encouraged residential areas that benefit safety from tsunamis and ocean views.
Minerals in your daily life: a game for science education
Authors: Teixeira Isabel , Lima Dulce
Published: February 2023

Quality education is one of the Sustainable Development Goals defined in the United Nations 2030 Agenda. Since traditional, purely expository, and transmissive teaching is neither attractive nor encourages students' attention, teachers must be able to meet current educational challenges, such as making teaching more attractive and motivating for developing multidisciplinary skills. Critical thinking, creativity, collaboration, and communication are highlighted as innovative and primordial skills for students of the 21st century. The curricular guidelines for the Natural Sciences discipline in middle school in Portugal emphasize the relevance of Science in everyday life and its application in technology, society, and the environment. The teaching of Geology can be based on methodological diversity and strategic pluralism, using experiences of daily living to highlight the presence of this Science. Game-based learning promotes changes in conceptions about the value of Geology in society, often undervalued and misunderstood by students due to its inherent complexity. To overcome this constraint, contextualized teaching enhances the understanding of the content, fostering interest and relevance of its knowledge. In this teaching perspective, students are faced with real situations perceived as meaningful to them, allowing these students to relate Science to their daily lives, namely to social matters and technological innovations. The game is a valuable didactic resource in the educational context, enhancing learning of Geosciences. Our poster presents the board game Minerals in your daily life, designed to explore the content Rocks and Minerals, transversal to the sub-themes External Dynamics of the Earth and Geological Science and Sustainability of Life on Earth, defined in the curriculum of the Natural Sciences discipline of middle school in Portugal (K7). The purpose of this resource is to allow the identification of minerals associated with students' everyday objects. Hence, the information described on the game cards will be used to guide them autonomously in the construction of knowledge. The students are organized into teams with the objective of winning the game by "collecting" the largest number of minerals from their identification. In sum, game-based teaching promotes meaningful learning among students, prompting their enthusiasm, motivation, and active participation throughout the activity. These positive results are illustrated by some of the students’ comments, "I like learning by playing" and "Learning this way helps me acquire knowledge". In addition to fostering autonomy and collaboration among peers, communication is stimulated by discussing and reflecting on the information displayed on the game cards.
Evaluation of total electron content derived from the spaceborne receivers of GRACE/GRACE-FO missions
Authors: Zheng Yuhao , Xiong Chao , Jiang Haicheng , Yin Fan , Stolle Claudia , Kervalishvili Guram
Published: February 2023

The Gravity Recovery and Climate Experiment (GRACE) and its follow-on mission GRACE-FO are gravity satellites jointly developed by the National Aeronautics and Space Administration (NASA) and German Aerospace Center (DLR), which are composed of two satellites. Such tandem satellite missions provide us with a good opportunity to evaluate the ionospheric total electron content (TEC) derived from their onboard global positioning system (GPS) receivers. In addition, the K-band ranging system (KBR) between two satellites provides also the in-situ electron density (Ne) at the satellite orbits, which can help further to evaluate the reliability of TEC. By combing the observations from GRACE and GRACE-FO, 20 years of data (from 2002 to 2022) have been accumulated to analyze the solar cycle dependence of TEC and Ne at the topside ionosphere. Our results show that the TEC from the tandem satellites is generally the same, but slight differences can still be found, showing solar cycle and local time dependences. In addition, we found that the TEC differences between the tandem satellites of GRACE are somehow smaller than that of GRACE-FO, and the consistency between the TEC and inter-satellite electron density results of GRACE is also better.
Morphological changes in a planted coastal dune field: measurements and modelling
Authors: Strypsteen Glenn , Rauwoens Pieter
Published: February 2023

In front of the traditional dike at Oosteroever, Belgium, a new 120x20 m² artificial dune with planted marram grass of different densities and patterns was built in January 2021. This man-made dune was constructed to reduce the local aeolian sand nuisance on the dike. The complex interaction between aeolian sand transport and vegetation will ensure future morphological development of a dune body strengthening the local coastal protection. For an optimal design of these planted dunes, a fundamental knowledge of morphological changes is required. This study is twofold: 1) Investigate dune growth by exploring a multi-monthly field dataset of wind characteristics and high-resolution topographic data, 2) Development and assessment of the AeoLiS model for simulation of this new planted coastal dune field. The performance of AeoLiS is analyzed by comparing observed and simulated results of erosion and deposition patterns and cross-shore bed level changes. The total volume of sand in the dune has increased significantly since the plantation of marram grass, resulting in 15 m³ m-1 due to aeolian sand transport from the surrounding beach. Most dune growth occurred during the first year. Dune growth during the second year was less pronounced and was attributed to the influence of supply limitations, vegetation characteristics, and sediment erosion by wind and storm events. The results of the model simulations demonstrate that AeoLiS can replicate the spatial patterns and profile development inside the artificial dune area to some extent. However, to adequately account for the interaction between vegetation and aeolian sand transport, the model's treatment of vegetation dynamics needs to be improved.
Two daily stability patterns in the atmospheric surface layer of the coast of Qatar
Authors: Sadr Reza , Li Yuan
Published: February 2023

The atmospheric stability condition in the coastal region of Qatar are analyzed using the measurements conducted on the shoreline (26.08N, 51.36E). The micrometeorological data are collected, from August 2015 to September 2016, using sonic anemometers (20 Hz) at three heights and a weather station on the top of a 9 m tower. Two different atmospheric daily stability patterns, ‘orderly’ and ‘disheveled’, are identified based on the wind conditions. A day is classified as ‘orderly’ if the amount of wind from the sea lasts less than 10% of the day. Otherwise, a day with an onshore wind of more than 10% is considered ‘disheveled’. The orderly stability pattern shows a daily descending and ascending trend during the sunrise and sunset periods, respectively, while the disheveled days follow a random pattern with no clear order. The probability distribution of the stability parameter shows a narrower distribution for the ‘orderly’ days, containing fewer unstable periods than the ‘disheveled’ days. The chaotic trend during disheveled days could be caused by the inhomogeneity of the roughness between the land and the sea (1000 times). The integral length scales are further investigated to clarify the influence of the local thermally forced flow to the disheveled patterns.
Analysis of changes in Local Climate Zone and Urban Heat Island phenomenon of new towns in South Korea according to urban planning
Authors: Lee Kyungil , Park Seonyoung
Published: February 2023

In comparison to naturally developed cities, a new town is strategically built in a short period of time according to development plans. It is considered as an appropriate study area for analyzing the urban climate issues such as Local Climate Zone (LCZ) and Urban Heat Islands (UHIs) phenomenon that are differently generated according to urban planning and development. However, there are few research on comparative investigation of new towns based on urban planning due to several external variables such as environmental considerations and economic situations. In this study, we suggest comprehensive method for determining and comparing changes in LCZ distribution and UHI phenomenon in two new towns in South Korea  with different urban planning. The LCZ distribution for each new town was analyzed using Sentinel 1&2 imagery as the main material, and Convolutional Neural Networks (CNN) method, a one of the deep learning algorithms. In addition, the UHI phenomenon was analyzed using Landsat imagery and the constructed LCZ map. These results have the potential to improve knowledge of the thermal environmental implications of urbanization and give guidance for sustainable urban development and maintenance when combined with architectural evaluation models.
Linking rifted margin crustal shapes with the timing and volume of magma emplacement
Authors: Manatschal Gianreto , Tomasi Simon , Chenin Pauline , Kusznir Nick
Published: February 2023

The binary magma-rich vs. magma-poor classification of rifted margins was introduced to distinguish between margins showing markedly different crustal architectures, in particular related to the occurrence of magmatic products: the “magma-poor” qualifier is attributed to margins that display a domain of exhumed mantle and whose crustal wedge is exclusively made of continental material, while margins whose continental crust is heavily intruded and overlain by extrusive magmatic flows (e.g., seaward dipping reflections (SDRs) in seismic sections) are regarded as “magma-rich”. Yet, distinguishing between inherited continental crust, newly created magmatic crust and serpentinized mantle in seismic data is challenging due to the comparable geophysical properties (density and seismic velocity). The only interfaces that can usually be identified with some confidence on seismic images are the top of the pre-rift basement and seismic Moho, which allow the determination of the first-order crustal shape of rifted margins. We investigate what the shape of rifted margins can tell us about the timing and volume of magma emplacement during rifting. We use a simple geometric/kinematic model to explore how the volume of magma and the timing of emplacement relative to crustal thinning impact the crustal shape and discuss how this approach may help us to better interpret and understand the tectono-magmatic processes at play during rifting.We show that crustal shape and inflection points at distal margins can be used to identify magma-poor rifted margins and the occurrence of exhumed mantle. Moreover, the crustal shape and inflection points of magma-poor rifted margins provide direct insights into the dominant processes controlling crustal thinning (e.g., pure-shear stretching, viscoplastic necking, and Coulomb controlled hyperextension) and also the delay of magma emplacement with respect to crustal thinning (e.g., inherited depleted subcontinental mantle, extension rate).In contrast, shapes of magma-rich margins are more challenging to interpret due to the difficulty to distinguish between continental and magmatic material. We show that different factors may impact the budget and/or timing of magma emplacement and control their distinctive shape, including: (1) the initial conditions from inheritance (e.g., mantle temperature, fertility, and water content); (2) the mode of lithosphere extension (e.g., pure shear vs. depth-dependent lithosphere thinning); and (3) external rift-independent factors (e.g., elevated temperature from mantle plumes).Crustal shapes allow us to define modes and conditions of crustal thinning at so-called magma-poor rifted margins. In contrast, to interpret crustal shapes of so-called magma-rich rifted margins and understand their tectono-magmatic evolution requires additional information such as timing and budget of magma-emplacement in the crustal wedge, paleo-bathymetry and subsidence history.
Aerosol–cloud interaction in the atmospheric chemistry model GRAPES_Meso5.1/CUACE and its impacts on mesoscale numerical weather prediction under haze pollution conditions in Jing–Jin–Ji in China
Authors: Zhang Wenjie , Wang Hong , Zhang Xiaoye
Published: February 2023

The representation of aerosol–cloud interaction (ACI) and its impacts in the current climate or weather model remains a challenge, especially for severely polluted regions with high aerosol concentration, which is even more important and worthy of study. Here, ACI is first implemented in the atmospheric chemistry model GRAPES_Meso5.1/CUACE by allowing for real-time aerosol activation in the Thompson cloud microphysics scheme. Two experiments are conducted focusing on a haze pollution case with coexisting high aerosol and stratus cloud over the Jing–Jin–Ji region in China to investigate the impact of ACI on the mesoscale numerical weather prediction (NWP). Study results show that ACI increases cloud droplet number concentration, water mixing ratio, liquid water path (CLWP), and optical thickness (COT), as a result improving the underestimated CLWP and COT (reducing the mean bias by 21% and 37%, respectively) over a certain subarea by the model without ACI. A cooling in temperature in the daytime below 950 hPa occurs due to ACI, which can reduce the mean bias of 2 m temperature in the daytime by up to 14% (∼ 0.6 ℃) in the subarea with the greatest change in CLWP and COT. The 24 h cumulative precipitation in this subarea corresponding to moderate-rainfall events increases, which can reduce the mean bias by 18%, depending on the enhanced melting of the snow by more cloud droplets. In other areas or periods with a slight change in CLWP and COT, the impact of ACI on NWP is not signifificant, suggesting the inhomogeneity of ACI. This study demonstrates the critical role of ACI in the current NWP model over the severely polluted region and the complexity of the ACI effect.
Analysis of wintertime ozone at two urban centres in western India.
Authors: Dhaka Shubham , Sharma Amit
Published: February 2023

Western India is a region which is exposed to pollution contributed by both natural and anthropogenic sources that may be local, regional or remote sources as reported in limited observational studies that have been conducted in the region. In the present study, temporal variation of surface ozone is studied at two urban centres (Jodhpur and Ajmer) in western India during a winter season (December 2018 – February 2019) by using ground based observation data from Central Pollution Control Board (CPCB). Jodhpur is found to have the higher seasonal average ozone (~48 µg/m3) with the daily mean values reaching to as high as 87.5 µg/m3. Ajmer closely followed with seasonal average ozone as ~44 µg/m3 and the daily mean values reaching upto 80 µg/m3. Diurnal trend (seasonally averaged) for ozone at Ajmer reveals comparatively higher afternoon values (even exceeding 100 µg/m3) but lower night time levels (close to 20 µg/m3) thus suggesting a stronger ozone production rate (~9.2 µg/m3/hr) at Ajmer during daytime (0600 – 1500 hrs local time). The ozone production rate at Jodhpur is lower (5.4 µg/m3/hr) during the same time due to lower afternoon values (~80 µg/m3) and higher nighttime levels (> 30 µg/m3). Subsequently, a detailed analysis is performed for the monthly peak ozone days in each winter month for both urban centres using ground based observation data, a back trajectory model  and a widely used reanalysis dataset. The analysis reveals contribution of both regional as well as long range transport from different directions in different months to higher levels of surface ozone, in addition to enhanced photochemistry and/or weak ozone titration on some days.  The ozone levels even breached the Indian National Ambient Air Quality Standards (NAAQS) limit of 100 µg/m3 set by CPCB for daily maximum 8 hour ozone concentration on some of the monthly peak ozone days at both urban centres. The study highlights the importance of transported ozone in enhancing ozone levels over the western India region during winter which may have severe impacts on vegetation, human health and climate change.
Usage of virtual TEC observations from empirical models for global ionospheric TEC modeling with spherical harmonic function
Authors: Wang Miaomiao
Published: February 2023

Global Navigation Satellite System (GNSS) is one of the valuable techniques used in researching ionospheric total electron content (TEC). GNSS observations above ground-based stations can be used to obtain high-precision ionospheric TEC with the so-called inverse technique. Subsequently, regional and/or global ionospheric TEC models could be established with some modeling techniques. Ionospheric TEC modeling with GNSS has become a great significance for improving the accuracy of GNSS navigation and positioning, as well as analyzing the ionospheric spatial structure, which is a great motivation to the development of ionospheric TEC modeling. There is no doubt that it is easier to get a satisfactory ionospheric TEC modeling result if the used stations are evenly distributed. However, stations are usually unevenly distributed because of some practical factors. For instance, there are few stations in ocean and Antarctic region. Due to lack of GNSS observations in ocean and Antarctic regions, ionosphere pierce points (IPPs) in these regions are also unevenly distributed or even blank. Consequently, the accuracy of ionospheric modeling is less satisfactory and some negative TEC values without physical meaning even occurred. In order to improve the accuracy of global ionospheric modeling, this work tries to solve this problem by using virtual TEC observations from empirical ionospheric models as constraints in global ionospheric TEC modeling. The spherical harmonic function was employed as the modeling technique, three empirical ionospheric models, Klobuchar, International Reference Ionosphere (IRI) and NeQuick, are used to calculate virtual TEC observations in four regions with no IPP, and GNSS observations above 279 global stations are used to calculate the ionospheric TEC values. Through experimental analysis, this work compares the accuracy improvement in global ionospheric modeling by using additional empirical constraints, and studies performance of the three used empirical ionospheric models in different IPP-blank regions. The results show that additional virtual TEC observations could effectively improve the accuracy of global ionospheric TEC modeling, especially for regions with very few IPPs. The contribution of TEC constraints from empirical models to global ionospheric modeling in different epochs is different. Taking the results in UT11 as an example, three empirical ionospheric models can improve the accuracy of global ionospheric modeling from 11.43 TECU to 3.28, 3.42 and 4.15 TECU, respectively. Generally, improvement performances of the three used empirical ionospheric models in mid-high latitude region and Antarctic are comparably, while Klobuchar model is relatively advantaged in mid-latitude region and IRI model outperforms the others in equator region.
Does soil structure affect water infiltration? Global results from a meta-data systematic review
Authors: Basset Christelle , Abou Najm Majdi , Hao Xiaoxiao , Daccache Andre
Published: February 2023

Soil structure is a crucial component of soil health and quality that significantly impacts water infiltration. Natural or anthropogenic drivers, such as soil management practices, can drastically alter soil structure, which in turn can affect water infiltration. These changes in soil structure have opposing effects on water infiltration into soils and are often difficult to quantify. Here, we present a narrative systematic review (SR) of the impacts of soil structure on water infiltration. Based on inclusion and exclusion criteria, as well as defined methods for literature search and data extraction, our systematic review led to a total of 153 papers divided into two sets: experimental (131) and theoretical (22) papers. That implied a sizable number of in-situ and field experiments that were conducted to evaluate the effects of soil structure on water infiltration under the influence of different land uses and soil practices. Significant effects of soil structure on water infiltration were inferred from analyzing the metadata extracted from the collected articles. These effects were further linked to land use and management, where we demonstrated the influence of three distinct categories: tillage, crop management, and soil amendments. Additionally, significant correlations between infiltration rate and soil structural characteristics were established, with R2 values ranging from 0.51 to 0.80, as well as between saturated hydraulic conductivity and soil structural characteristics, with R2 values varying from 0.21 to 0.78. Finally, our review emphasized the significant absence of and the need for theoretical frameworks studying the impacts of soil structure on water infiltration.
Sea level variability across the Northwest Atlantic shelf
Authors: Abele Anrijs , Royston Sam , Bamber Jonathan
Published: February 2023

Ocean dynamics plays a prominent role in the change of sea level variability on approach to the coast. While some studies have focused on decadal changes at tide gauges, a gap remains in understanding higher frequency variability, which provides a significant proportion of total variability in the coastal region. The Northwest Atlantic, an area including the U.S. East coast and Atlantic Canada, is a known hotspot of sea level rise and shows spatial differences in lower frequency variability along the shelf. However, the higher frequency variability is rarely explored, despite being at least partly captured by the observation systems.In this study, we evaluated the sea level variability across the sub-annual timescales on the shelf of the Northwest Atlantic and linked it to the local and far-field ocean dynamics. The drivers of sea level variability include both wind-driven and buoyancy-driven circulation. We used high-frequency tide gauge records, eddy-resolving high-resolution (1/12°) ocean reanalysis, and high-precision synthetic aperture radar (SAR) altimeter along-track data to obtain sea level anomalies for the analysis. We evaluated the coherence of sea level signal for all sources and with the drivers of ocean circulation.
Improving Data-Driven Flow Forecasting in Large Basins using Machine Learning to Route Flows
Authors: Lambl David , Elkurdy Mostafa , Butcher Phil , Read Laura K , Sampson Alden Keefe
Published: February 2023

Producing accurate hourly streamflow forecasts in large basins is difficult without a distributed model to represent both streamflow routing through the river network and the spatial heterogeneity of land and weather conditions. HydroForecast is a theory-guided deep learning flow forecasting product that consists of short-term (hourly predictions out to 10 days), seasonal (10 day predictions out to a year), and daily reanalysis models. This work focuses primarily on the short-term model which has award winning accuracy across a wide range of basins.In this work, we discuss the implementation of a novel distributed flow forecasting capability of HydroForecast, which splits basins into smaller sub-basins and routes flows from each subbasin to the downstream forecast points of interest. The entire model is implemented as a deep neural network allowing end-to-end training of both sub-basin runoff prediction and flow routing. The model's routing component predicts a unit hydrograph of flow travel time at each river reach and timestep allowing us to inspect and interpret the learned river routing and to seamlessly incorporate any upstream gauge data. We compare the accuracy of this distributed model to our original flow forecasting model at selected sites and discuss future improvements that will be made to this model.
Contributions of atmospheric forcing and ocean preconditioning in the 2016 Antarctic sea ice extent drop
Authors: Mezzina Bianca , Goosse Hugues , Huot Pierre-Vincent , Marchi Sylvain , Van Lipzig Nicole
Published: February 2023

The observed evolution of Antarctic sea ice extent is marked by an abrupt decrease in 2016/2017. After several years of gradual increase culminated in an all-time record high in 2014/2015, a rapid decline in 2016 led to an unprecedented minimum, and unusual low extents have been observed since then. Even though this record has now been beaten, the sudden drop from extreme high values to a minimum in less than two years is unique to this event, whose dynamics are still uncertain. While it was likely triggered by anomalous atmospheric conditions in the prior months, the contribution of the ocean conditions, as a preconditioning which amplified the response of the sea ice or helped to maintain the anomalies for a longer period, still needs to be quantified. 
To evaluate the respective influences of the atmosphere and ocean on this 2016 event, we have performed sensitivity experiments using the circum-Antarctic fully coupled model (ice-sheet–ocean–sea-ice–atmosphere) PARASO. First, a control experiment with the model forced by lateral boundary conditions derived from observations (ERA5 in the atmosphere, ORAS5 in the ocean) is performed over the period 1985-2018. In such a set-up, the model correlates well with the observations and is able to capture the 2016 drop. Then, the model is integrated again between 2016 and 2018 with the same atmospheric boundary forcing, but with different initial conditions in the ocean: namely, ocean conditions from previous years in the control run are used as initial state in 2016 in the sensitivity experiments, producing an ensemble of 5 members.
Preliminary results indicate that the 2016 drop is captured by all members, suggesting the atmospheric boundary forcing as the dominant driver and confirming that the event is induced by large-scale atmospheric dynamics. However, some variability is present in the amplitude and timing of the drop, as well as in the evolution and recovery of the sea ice in the following months, which may be influenced by the different states of the ocean. Related processes are further investigated by examining different oceanic and atmospheric fields, focussing on the role of ocean preconditioning by identifying the differences between the members and their impact. 
Genesis and Origins of Natural Gas in Eastern Belt around Penyijingxi Sag in Junggar Basin, NW China
Authors: Liu Keshun , Qu Jiangxiu , Zha Ming , Ding Xiujian
Published: February 2023

Abstract: The Junggar basin is sandwiched between the Siberian plate, the Kazakhstan plate and the Tarim plate, and is an important part of the Central Asian orogenic belt. Based on the comprehensive analysis of the characteristics of the natural gas composition，carbon isotope, light hydrocarbons and source rocks in the eastern belt around Penyijingxi Sag, Junggar Basin, i.e., our studied area, the genesis and origins of natural gas in this area are discussed. The natural gases in the eastern belt around Penyijingxi Sag, are dominated by alkane gases, and have relatively low contents of heavy hydrocarbons and non-hydrocarbons. Methane is dominant in alkane gas, with volume fraction varies from 70.36% to 93.34%. In non-hydrocarbon gas, the volume fraction of nitrogen varies from 0.69% to 11.95%, and the volume fraction of carbon dioxide varies from 0 to 1.49%. The values of δ13methane(C1), δ13ethane(C2), δ13propane(C3) and δ13butane(C4) of natural gas are in the ranges from −45.57‰ to −31.19‰, −31.69‰ to −24.66‰, −28.76‰ to −23.56‰, −27.96‰ to −23.64‰, respectively. The overall carbon isotopic composition of the alkanes shows a trend as δ13C1 < δ13C2 < δ13C3 < δ13C4, and all δ13C1 values are ≤ -30‰, which are typical of gases of organic origin. The methane and ethane isotopic compositions and the characteristics of light hydrocarbons show that the natural gases in the studied area are dominated by coal-type gas and contain a small amount of oil-type gas. Specifically, the coal-type gas is from the mature to highly mature source rocks of the Lower Urho Formation, and the oil-type gas is from the mature to highly mature source rocks of the Fengcheng Formation. Analysis of gas migration parameters show that, while there was no significant lateral migration of natural gas in the studied area, natural gases once migrated vertically and resulted in the mixing of oil- and coal-type gases as well as the mixing of alkane gases of the same genetic type formed at different stages, which should be the cause of observed reversed carbon isotopic series. The diffusion and migration of carboniferous oil and gas after reservoir formation have led to differences in gas geochemical characteristics among gas wells in this area, which may provide important information for oil and gas exploration in the central Junggar Basin.Keywords: Junggar Basin; geochemistry; natural gas genesis; carbon isotopes; light hydrocarbons
Assessing the temporal origin of root water uptake and drainage water using a virtual tracer experiment in HYDRUS-1D
Authors: Nasta Paolo , Zhou Tiantian , Stumpp Christine , Simunek Jirka , Romano Nunzio
Published: February 2023

The temporal origin of root water uptake and drainage provides insights into the impact of natural and anthropogenic disturbances on plant resilience and aquifer vulnerability. In-situ and virtual tracer experiments provide information on rainfall partitioning and transit times, which help to enhance the understanding of the hydrological response of a soil-plant-atmosphere continuum (SPAC) to climate variability and contaminant transport. A virtual tracer experiment was carried out in a 150-cm-thick soil lysimeter planted with winter rye in Austria. Water flow and tracer transport dynamics were simulated in the SPAC using HYDRUS-1D, previously calibrated with hydrochemical measurements. The root water uptake (τR) and drainage (τD) transit times (τ) were assessed by identifying arrival times when a prescribed percentage of the tracer mass breakthrough curves was reached. The estimates of τR and τD were compared to those derived from a particle tracking algorithm that simulates the particle trajectories subject to convective transport. The tracer-based arrival times were in close agreement with those determined using particle tracking when 50% of the tracer output flux was reached. On average, it took 19 or 234 days for water originating from rainfall in the growing season to be taken up by roots (21%) or exit as drainage (36%), respectively. In contrast, in the dormant season, 10% of rainfall water was taken up by roots after 245 days, while 79% became drainage after 241 days. The results from each daily event can be aggregated at any desired temporal resolution to investigate the effects of climate seasonality on water balance and timing. The temporal origin of water can be explored in other plots using the standard guidelines proposed in this study.
Mechanical/Hydraulic Aperture of 3D-Printed Joints in Relation to JRC and Surface Geometry
Authors: Le Tan-Minh , Nguyen Xuan-Xinh , Dong Jia-Jyun
Published: February 2023

A thorough understanding of the hydro-mechanical behavior of rock joints is essential since joints typically serve as weak planes and fluid channels within rock masses. Joint roughness, among other factors, dominates the mechanical and hydraulic behavior of rock joints directly. Since 1970s, the joint roughness coefficient (JRC) has been used extensively to quantify joint roughness. As a result of using this variable in empirical equations, we can now anticipate the fluid flow characteristics under stresses. However, the validity of utilizing a single parameter to express the complicated geometry of joint surfaces should be testified. We used three-dimensional (3D) printers to produce a large number of joint samples with similar JRC (2 - 4) but varying surface geometry, including matched and mismatched joint surfaces. The mechanical and hydraulic apertures (E and e) of the printed joint samples were determined utilizing high confining pressure, permeability/porosity measurement equipment (YOKO2). The relationship between E and e can thus be quantified. The results indicate that the stress-dependent mechanical apertures of matched and mismatched joints with similar JRC is significantly different and result in the difference in e-E relationship. However, the measured e-E relationship is quite similar for matched or mismatched smooth joints regardless of joint surface geometry. To conclude, JRC is an appropriate index of smooth joint roughness for representing the stress-dependent e and E and accompanying e-E relationship.   
Satellite remotely-sensed data for studying the impact of climate change on crop evapotranspiration in Cyprus
Authors: Michaelides Silas , Papadavid George , Hadjimitsis Diofantos , Kountios Georgios
Published: February 2023

Recent studies have shown that climate change is likely to affect the agricultural sector in Cyprus. In the present study, crop water requirements in each of the 1995–2004 and 2010-2019 decades are estimated, by employing the same methodology, and subsequently compared. The aim is to investigate whether there has been any significant change regarding the crop water requirements of the most water-intensive crops in Cyprus. For the estimation of the crop evapotranspiration, the FAO Penman-Monteith methodology is used, as this has been adapted to satellite data. Remote-sensing data from Landsat TM/ETM+/OLI were employed.Five water-intensive crops are in the focus of this research: citrus, bananas, colocasi, potatoes, and avocado. For each of these crops, estimations of the crop evapotranspiration were performed, considering three agricultural areas on the island where these crops are grown:  Pafos, Polis, and Famagusta.The results have shown that there is no significant effect of climate variation on crop evapotranspiration, despite the fact that some climatic factors have exhibited a change on the island of Cyprus; the mean values for the most water-intensive trees/crops in Cyprus in the 1994–2004 decade have shown no significant difference from the mean values in the 2010–2019 decade, for all the crops and all agricultural areas. From the statistical analysis performed, it can be concluded that the climate change which has been documented in the past decades has not impacted significantly the crop evapotranspiration.The authors would like to express their thanks to the Agricultural Research Institute for providing the proper resources for applying the specific methodology. Also, the authors acknowledge the ‘EXCELSIOR’: ERATOSTHENES: EΧcellence Research Centre for Earth Surveillance and Space-Based Monitoring of the Environment H2020 Widespread Teaming project (www.excelsior2020.eu). The ‘EXCELSIOR’ project has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No 857510, from the Government of the Republic of Cyprus through the Directorate General for the European Programmes, Coordination and Development and the Cyprus University of Technology.
Inverse Absolute Height Weighting in the Highest Order Levelling Networks
Authors: Cvetkov Vasil , Gospodinov Slaveyko
Published: February 2023

The North American Vertical Datum of 1988 (NAVD88) was established by the minimum-constrain adjustment of geodetic levelling observations in Canada, USA, and Mexico. It held fixed the height of the primary tidal benchmark at Rimouski, Quebec, Canada. The NAVD88 datum was never officially adapted in Canada due its large east-west tilt of 1.5 m from the Atlantic to Pacific coast (Hayden et al., 2012). Also, a large systematic difference (ranging from -20 cm to +130 cm) was found between NAVD88 and the pure geoid gravimetric models. Using Factor Analysis it was discovered that one of the factors, which can explain the tilt of the NAVD88, is the terrain, i.e. small in the flat states but large in the mountainous areas such as in the Rockies and the Appalachians (Li, 2012). A possible reason for the tilt of the NAVD88 might be the weights used into adjustment of the network. In this study the data of two precise national levelling networks are used, e.g. the Second Levelling of Finland and the Third Levelling of Bulgaria, in order to support the above hypothesis. An iterative procedure based on the Inverse Absolute Height Weighting (IAHW) is applied. The core of this procedure is to find this value of the power parameter (p) of the weights w=Hp, where H is the absolute elevation difference of the terminals in the levelling lines, that minimize the mean of the mean squared errors (MSE) of the nodal bench marks (NBM) in both networks. It has been found that p=1 and p=4.3 for the Bulgarian and the Finnish networks, respectively. Also, a similar iterative procedure based on the Inverse Distance Weighting (IDW) is performed and the best decisions for the Finnish and the Bulgarian networks are obtained. It has been found that the weights w=L-5.9 and w=L-1.6, where L is the length of the levelling line, lead to the minimal MSE of the NBM for the Finnish and the Bulgarian networks, respectively. The results of both the IDW and the IAHW procedures are compared. It has been revealed that the IAHW based adjustments lead to significantly less MSE of the NBM than all variants of the IDW. It has also been shown that concerning the Bulgarian and the Finnish analyzed here data, the IAHD approach leads to physically lower adjusted heights than the IDW. In some cases these differences are more than 1.5-2 times greater than the MSE of the corresponding bench marks.
Landscape pattern change affect runoff and sediment yield in Nandong underground river system, Southwest China
Authors: Liu Peng , Li YanQing , Yu Yang
Published: February 2023

In fragile karst watershed, landscape pattern mainly affects evapotranspiration, interception, surface runoff, soil water infiltration and groundwater formation through spatiotemporal variation of land use, vegetation pattern, and then influences the discharge and sediment transport. A new Vegetation-Topographic factor (VTF)was constructed by NDVI and DEM data from 2000 to 2018. Based on VTF classification , Vegetation-Topographic landscape index(VTLI) was calculated by FRAGSTATS to analyze the impact of VTLI change on runoff and sediment yield in Nandong underground river system（NURS）. The results showed that :(1) PD, IJI, LSI, SHDI were significantly positively correlated with runoff and sediment, while AI, CONNECT were significantly negatively correlated with runoff and sediment yield(P<0.05). LPI and DIVISION indices were not significantly correlated with discharge, but positively correlated with sediment yield. (2) PD, IJI, LSI and SHDI were the main promoting factors for runoff, while LSI and SHDI were the main promoting factors for sediment yield. CONNECT and AI were the main restrain factors of sediment yield, Which showed a downward trend. (3) In urban areas, VTF was decreased and has persistence trend. In basin-mountain margin areas, VTF was increased and has persistence trend. In mountain area, VTF was unchanged or not significantly increased but was anti-persistence trend. The change of landscape pattern indexes varied the runoff and sediment yield of NURS. The trend and persistence of VTF vary greatly in different geomorphic positions of NURS. These results will provide theoretical basis for watershed management and soil conservation of karst fragile ecosystem in southwest China. 