bluuebunny/crossref_metadata_2025 huggingface dataset:
Progress of reprocessed long-term data records from Fengyun satellites
Authors: Sun Ling , Zhang Peng , Wu Shengli , Qiu Hong , Chen Lin , Guo Yang , Xu Na , An Dawei , Qi Chengli
Published: February 2023

NSMC/CMA has been continuously pushing forward the reprocessing of Fengyun series dataset for better quality, especially L1 product. A comprehensive Fengyun historical data rescue and reprocessing task has been completed. At present, the early historical data of FY-1 archive was rescued and L1 data was reproduced providing full data record since 1988. The long-term L1 data reprocessing includes 7 instrument series on 13 satellites in FY-1, FY-2 and FY-3 missions. There are 3 optical imagers with 2 in polar orbit and 1 in geostationary orbit, 1 infrared sounder, 1 microwave imager, and 2 microwave sounders. After reprocessing, the sensor related instability issues caused by instrument degradation and instrument status changes are solved. The inter-platform consistency is also improved by radiometric reference transfer correction in each instrument series. The Fengyun fundamental climate data records (FCDRs) for 7 instruments have been evaluated by radiometric comparison with reference instruments or RTM simulations. The reprocessed L1 dataset has also supported long-term dataset generation for several geophysical parameters. This paper gives an overview of the data reprocessing efforts. 
Millimeter slope seasonal deformation from multitemporal InSAR with a tropospheric delay correction: a case in Hong Kong
Authors: Shi Guoqiang
Published: February 2023

Rainfall induced landslides have been the No.1 geohazards in Hong Kong (HK). In coastal subtropical monsoon regions, air temperature and humidity vary substantially and frequently. Tropospheric delays (TDs) limit the accurate detection of slow slope motion (which is the common case in HK) using interferometric synthetic aperture radar (InSAR).  In this presentation, we introduce a new TD correction method for InSAR line-of-sight (LOS) measurements at individual slope scale. The TD signal was estimated from LOS time series through a blind source separation (i.e., independent component analysis). The stratified TD was isolated according to a spatially elevation-linked and temporally periodic independent-component (IC), which was determined via a correlation test and power spectrum analysis. Therefore, the TD correction was not relying on any external weather products/meteorological data and had unprecedented spatiotemporal details equivalent to the SAR images.A case study in Tai O, HK was conducted to verify the proposed method using 63 descending CosmoSkyMed (CSK) and 143 ascending Sentinel-1 (SNT-1) images. We used meteorological data of air temperature, humidity and weather products of ECMWF (European Centre for Medium-Range Weather Forecasts) ERA-5 and GACOS (Generic Atmospheric Correction Online Service) to validate the estimated TD. We estimated up to 3-4 cm spatiotemporally relative TD in the LOS directions of CSK and SNT-1, corresponding to a slope elevation change of ~ 400 m. The estimated TD was largely affected by specific air conditions (e.g., temperature and humidity) on the SAR image-acquisition days. In addition, we found the relative TD exhibited a slower increment rate than that of the slope elevation, suggesting the TD was not linearly related to the elevation. Ground deformation measurements from prisms and records of rainfall and tide were used to validate and interpret the InSAR deformation time series. It is interesting to find different hydrological forcings regulate the seasonal deformations in the slope (~ 10mm) and the reclamation (~ 15mm) in Tai O. Downslope movement (due to increase in pore-water pressure) occurred when rainfall accumulated from a dry season to a wet season, whereas upslope rebound (due to soil shrinkage) occurred when rainfall decreased from a wet season to a dry season. However, the periodic deformation of the reclamation substrate seemed to be more related to the sea level, instead of rainfall. The TD correction has reduced the root-mean-square error (RMSE) by 42.3%, such that InSAR LOS time series with millimeter-level accuracy (potentially 1-3 mm) were obtained in the Tai O case.
Unraveling the effects of geomorphic restrictions on sediment connectivity in a debris flow small watershed
Authors: Zhao Peng , Wang Daojie , He Songtang , Pei Zengli
Published: February 2023

Sediment (dis)connectivity plays a critical role in influencing the geomorphic processes and sediment delivery in debris flow areas. Similarly, changes in geomorphic constraints have a significant impact on sediment connectivity. Therefore, understanding the potential effects of geomorphic indicators on sediment connectivity can identify geomorphic adjustment hotspots and help to inform geo-geomorphic hazard prevention and control. To explore the effects of geomorphic restrictions on sediment connectivity, we applied an index of connectivity (IC) and the digital terrain analysis (DTA) in Jiangjiagou Gully, Yunnan Province, SW China, which is famous for its high annual occurrence of debris flow events. And according to the natural topography conditions, the watershed was separated into three sections from up to down. The IC and 13 geomorphic indicators are calculated for each cell of the watershed’s 5 m resolution digital elevation model (DEM). GeoDetector was used to investigate the geomorphic indicators and their interactions affecting the spatial distribution of sediment connectivity. The results showed that the IC and geomorphic indicators have significant spatial heterogeneity in different regions. The IC value varied from -20.74 to 1.42 and the high-value areas overlap with the river network. LS factor, Topographic Characterization Index (TCI), and Terrain Roughness (TR) are the three factors with the greatest impact on IC value for all regions. In addition, the interactions significantly enhanced the explanatory power of single indicators. Particularly, Topographic Wetness Index (TWI), while single explanatory power is extremely low, its interactions display higher influences than others. Therefore, carrying out low-cost geomorphic adjustments based on the key geomorphic indicators can reduce or block sediment connectivity, further achieving the aim of water and soil conservation and geo-geomorphic hazard control. This study contributes to improving our understanding of the geomorphic processes and provides a scientific basis for nature-based solutions in typical debris flow small watersheds.
Experimental volcanic lightning under conditions relevant to the early Earth: Discharges as a possible prebiotic synthesis mechanism
Authors: Springsklee Christina , Scheu Bettina , Seifert Christoph , Cimarelli Corrado , Gaudin Damien , Dingwell Donald B. , Trapp Oliver
Published: February 2023

Far from being a recent development of the Earth System, volcanism has accompanied the Earth, terrestrial planets and countless exoplanets since their origins. Volcanism is a material mechanism whereby planets evolve to their differentiated states that are potentially capable of hosting life. Explosive volcanic eruptions are commonly accompanied by volcanic lightning, modulated by charging and discharging mechanisms within the eruption column. As discharges have been proposed as a potential prebiotic synthesis mechanism for forming first organic molecules, the behaviour of volcanic lightning at early Earth conditions could yield further insights into likely environments for the origin of life.Earth´s atmosphere has changed significantly in composition and pressure since its early beginnings. Here, we would like to investigate how volcanic lightning might have operated and was influenced by changes in those environmental conditions. For this purpose, we have developed an experimental device, which consists of a gas-tight modification of a shock-tube apparatus, to investigate experimental discharges in decompressed jets of gas and volcanic ash particles under varying atmospheric conditions. The setup acts as a Faraday cage, capable of measuring discharges close to the vent. The gas inside the particle collector tank is sampled by crimp cap bottles and analysed by gas chromatography. We modified the enveloping atmospheric composition and pressure (200 mbar – 4 bar) and the transporting gas phase (argon and nitrogen).We have tested atmospheres containing carbon dioxide, nitrogen and carbon monoxide to mimic early Earth conditions and obtained discharges with similar magnitude to those achieved in an air atmosphere. We have also varied the atmospheric pressure and observed that decreasing the atmospheric pressure results in less discharges. The results of the experiments demonstrate that it is the coupling between gas and ash particles which largely governs the occurrence and magnitude of discharges close to the jet nozzle. Nitrogen as transporting gas results in fewer discharges compared to argon, emphasizing the importance of the composition of the transporting gas phase in the jet charging and discharging mechanisms. The preliminary results point to active volcanic settings under varying atmospheric conditions as multivariate environment for the emergence of life and thus our experiments continue.  
Spatial differences in the response of Ginkgo spring leaf phenology to climate change
Authors: Wu Zhaofei , Fu Yongshuo , Zohner Constantin
Published: February 2023

Climate change-induced spring phenological shifts exert significant effects on terrestrial carbon, water and nutrient cycles as well as the climate system. Spring leaf-out of temperate trees is triggered by a combination of winter chilling, spring temperature and photoperiod. Yet, the effects of these cues along elevation and latitude remain poorly understood due to the lack of experiments. Here we test for elevational and latitudinal differences in the responses of spring leaf phenology to climate by conducting a manipulative experiment with four temperature (5, 10, 15, and 20 °C) and two photoperiod (8 and 16 h) treatments, using twigs from mature Ginkgo trees at two latitudes in China (39° 54′ N and 30°19′ N) and three elevations at the low latitude site (344, 826, 1098 m). We found that the responsiveness of leaf unfolding to temperature and photoperiod decreases with increasing elevation. Specifically, the temperature sensitivity of leaf unfolding (defined as the leaf-out advance per degree warming, ST) was higher (4.17 days °C−1) and the photoperiod effect on ST was larger (decrease of 1.15 days °C−1) at the lowest elevation than at the highest elevation (ST = 3.26 days °C−1; decrease of 0.48 days °C−1). This may be related to adaptation to local environments and self-protection mechanisms of trees at high elevations to avoid frost damage. In addition, we found that photoperiod only affected leaf unfolding at low latitudes, with long (16-h) days advancing leaf unfolding in low-latitude individuals by, on average, 8.1 days relative to short (8-h) days. Field phenological observations supported the experimental results. Our results suggest that, for a given species, populations growing under different climate conditions may exhibit different phenological responses to climate change, with individuals in warmer regions likely becoming increasingly limited by photoperiod as the climate warms further. We thus provide empirical evidence of spatial differences in the relative effects of spring temperature and photoperiod on spring leaf phenology, which is not yet accounted for in models of spring phenology.
Unravelling the origins of precipitation over the world’s water towers
Authors: Keune Jessica , Brunner Manuela
Published: February 2023

Mountain regions supply around 22% of the world's population with freshwater — from precipitation over these water towers to melt water from snow packs and glaciers. However, the frozen reservoirs of water that usually act to buffer precipitation deficits are diminishing as a result of climate change. As a consequence, precipitation will become the main source of freshwater supplied by these water towers. Yet, already today, precipitation deficits over many water towers frequently cause severe droughts that further induce supply deficits in downstream regions. Here, we unravel the origins of precipitation over the most important water towers worldwide and illustrate their dependency on upwind land regions. Using a moisture tracking framework constrained by satellite observations, we disentangle the local and remote surface drivers of drought over these water towers and highlight the role of forested and irrigated regions during these events. Our results indicate that many water towers can self-sustain their precipitation during drought events through an increased self-supply of moisture for precipitation: over the water tower of the Ganges-Brahmaputra, for example, around 80% of the precipitation during drought events is supplied by the water tower itself and its dependent downstream region. Our findings highlight the vulnerability of the world's most important water towers to drought from an atmospheric perspective and outline the potential of localized forest and land management practices to secure freshwater to billions of people in the future.
Stone Dolls
Authors: Perunovski Pane
Published: February 2023

The specific landforms created by the combined weathering processes by the exogenic forces are usually challenging to explain in a way a high school student would fully understand the process of their creation. The Stone Dolls of Kuklica are an example of earth pyramids which is a popular touristic landmark in the picturesque volcanic region of Kratovo in North Macedonia. We have made a model in which we recreate the process of their creation in an amusing way. The model is made of waterproof materials: plastic, stones, sand, Styrofoam, g and glue. The whole setting is placed inside a plastic pot where the Kuklica landscape is recreated. Then the pot is filled with sand which represents the softer rocks that used to exist around the stone pyramids. The bottom of the pot is perforated but closed until the beginning of the show. So, in the original sequence the setting is very simple and unattractive, a pile of sand collected in a plastic pot, which makes the surprise effect better. The students usually expect a cat to be included in the show. But then they see a plastic bottle marked as a cloud that brings rain and another pot used for collection of the ‘eroded material’. We open the bottom of the original pot, some sand escapes in the collection pot and then it starts raining from the bottle. The muddy sand slowly washes away and goes into the collection pot. Then some stones pop up. They stay firm and don’t let the rain take them down. The rain eventually weathers all the soft rocks away, leaving behind the wonderful landscape of the Kuklica Stone Dolls. 
Tropical Instability Waves in a High-Resolution Oceanic and Coupled GCM
Authors: Tianyan Li , Yongqiang Yu
Published: February 2023

Tropical instability waves (TIWs) are the dominant mesoscale variability in the eastern equatorial Pacific Ocean. TIWs have direct impacts on the local hydrology, biochemistry and atmospheric boundary layer, and feedback on ocean circulations and climate variability. In this study, the basic characteristics of Pacific Ocean TIWs simulated by an eddy-resolving ocean model and a coupled general circulation model are evaluated. The simulated TIW biases mainly result from the mean climatology state, as TIWs extract eddy energy from the mean potential and kinetic energy. Both the oceanic and coupled models reproduce the observed westward propagating large-scale Rossby waves between approximately 2-8N, but the simulated TIWs have shorter wavelengths than the observed waves due to the shallower thermocline. Meanwhile, the weak meridional shears of background zonal currents and the less-tilted pycnocline in these two models compared to the observations causes weak barotropic and baroclinic instability, which decreases the intensity of the simulated TIWs. We then contrast the TIWs from these two models and identify the roles of atmospheric feedback in modulating TIWs. The latent heat flux feedback is similar to observation in the coupled model but absent in the ocean model, contributing to the stronger standard deviation (STD) of the TIW SST in the ocean model. The ocean model is not able to capture realistic air-sea interaction processes when forced with prescribed atmospheric forcing. However, the misrepresented atmospheric feedback in the ocean model tends to decrease the sea surface height (SSH) variability, and the current feedback damping effect is stronger in the ocean model than in the coupled model. Combined with weaker barotropic conversion rate and baroclinic conversion rate in the ocean model than in the coupled model, the STD of the TIW SSH in the ocean model is weaker.
Heat accumulation in shallow aquifers: managing a growing resource
Authors: Bayer Peter , Attard Guillaume , Blum Philipp , Hemmerle Hannes , Kurylyk Barret L. , Menberg Kathrin , Noethen Maximilian , Benz Susanne
Published: February 2023

Heat loss from buildings, infrastructure and enhanced heat flow from sealed surfaces increase the temperatures of shallow groundwater often more than global warming. A worldwide analysis of thousands of wells reveals that the temperature at every second location is higher than expected, and local anthropogenic heat sources that exist for decades contribute to subsurface waste heat accumulation down to a depth of around 100 m. At some places, such as in the city centre of Cologne, heating of groundwater by several degrees of Celsius appears to have even reached a maximum. Here, long-term temperature records reveal stabilizing thermal conditions in the shallow aquifer. This also means that the geothermal potential has increased significantly, possibly to a critical level for maximum stored heat in place. Still, the natural geothermal resources together with the artificially stored resources are often overlooked. In many regions, recycling only the energy lost to the subsurface could (1) fulfil a substantial part of the heat demand of buildings, and (2) increase the efficiency of heat pumps with a more favourable thermal regime during the heating period. This resource is growing.  On the global scale, by the end of this century nearly 75% of the heat demand could be covered by recycling the heat that accumulates in the subsurface from anthropogenic heat loss and in response to climate change. Especially in densely populated areas, continued heat accumulation mitigates the risk of overexploiting the geothermal potential of shallow aquifers. Sustainable thermal management of aquifers must integrate concepts of heat recycling to avoid long-term warming of groundwater. For this, integrated spatial planning is needed. Shallow geothermal systems such as groundwater heat-pump installations have to be spatially organized in urban districts to achieve optimal use of the geothermal resource. They can maintain controlled cooling of the groundwater while benefitting from enhanced waste heat flux. As an example, we discuss the thermal interference of urban infrastructure and geothermal wells for the city of Lyon, which are spatially arranged based on hydraulic and thermal criteria to benefit from urban groundwater heating.
Impacts of the mid-15th century eruption at Kuwae caldera, Vanuatu
Authors: Stern Sönke , Cronin Shane , Bedford Stuart , Ballard Chris , Henderson Robert , Yona Salkon
Published: February 2023

In the AD 1450s, one of the three largest climate-forcing eruptions of the largest 1000 years took place, with similar impacts as the AD 1815 event of Tambora, Indonesia, that caused the ‘year without a summer’ of AD 1816. The submarine caldera of Kuwae, Vanuatu, has long been suggested to be the source of the AD 1450s eruption, but this is still highly debated.Today, the 12-by-6 km large Kuwae caldera lies between the islands of Epi and Tongoa. Here, an eruption occurred in the 15th century eruption and locally caused devastation, covering the islands surrounding it with vast amounts of pyroclastic material. We present the first full stratigraphy of the event, enabling us to reconstruct the eruptive sequence. First, a small ash plume produced fine ash deposits overlying faulted soil sequences, indicating a low-energy, precursory phase. Afterwards, the eruption built a Plinian eruption column, causing lapilli fall in excess of 3 m in proximal locations, and sending volcanic particles and gases high up into the atmosphere. This column then collapsed, producing the first pyroclastic flows that devastated the islands surrounding the caldera, incorporating many trees that became charcoalised and are still fully preserved in the deposits. Following further pyroclastic flow activity, a massive lithic lag breccia contains megaclasts (>10 m breccia), recording the collapse of a pre-existent edifice. Later pumice-rich pyroclastic flows occurred bring the total thickness of the sequence to between 30 and >80 m in proximal locations.These results are combined with initial results from a recent bathymetric study, mapping the submarine caldera floor, addressing the question of whether the entire caldera was generated during the mid-15th century event, or whether earlier eruptions have played a part in its collapse. This is essential for estimating the total collapse volume of the mid-15th century event at Kuwae, representative of the total erupted volume.We will use information on a) the eruptive sequence (based on field observations), b) eruptive volume (based on bathymetry), c) total emitted sulphur (based on eruptive volume and preliminary geochemistry data), and d) the eruptive date (based on radiocarbon analysis of collected charcoal samples) to characterise the mid-15th century eruption of the Kuwae caldera and test whether it was the source of the AD 1450s volcanic event that had a global climate impact.
Solar Potential in Saudi Arabia: Spatio-temporal and Plates-inclination Effects on the Performance of Photovoltaic Solar Panels
Authors: Farahat Ashraf , Kambezidis Harry
Published: February 2023

Inclined and flat-plate photovoltaic (PV) solar panels have been widely used in many countries and regions for generating electric power. For exploiting the available solar energy in a region, prior knowledge of this potential is necessary. This work investigates the performance of solar panels in 82 locations in Saudi Arabia by calculating the annual energy received on inclined-plate with tilt angles from 15° – 55° inclined to south and flat-plate that continuously follow the daily motion of the sun.  Calculations are performed using a fixed surface albedo of 0.2 and with a near-real value. The analysis indicates that tilt angles of 20°, 25°, and 30° towards the south are the optimum ones depending on the site. These optimum tilt angles define three distinct solar energy zones in Saudi Arabia. The variation of the total energy in each energy zone on a monthly, seasonal, and annual basis is given. Regression analysis for the total energy as a function of time is derived for each zone. Moreover, the spatial distribution of the annual global inclined solar energy in Saudi Arabia is illustrated in a solar map where the total energy is found to vary from 1612 - 2977 kWhm−2year−1 for the southward-inclined plates and 2159 – 4078 kWhm−2year−1 for the flat-plates across Saudi Arabia. The correction factor, introduced in a recent publication, is used; it is found that the linear relationship between the correction factor and the ground-albedo ratio is general enough to be graphically representable as a nomogram.
Permafrost degassing in Taylor Valley, Antarctica
Authors: Wilson Gary , Ruggiero Livio , Sciarra Alessandra , Mazzini Adriano , Florindo Fabio , Tartarello Maria , Mazzoli Claudio , Anderson Jacob , Romano Valentina , Ciotoli Giancarlo
Published: February 2023

Contemporary studies conducted in northern polar regions reveal that permafrost stability plays an important role in the modern carbon cycle as it potentially stores considerable quantities of greenhouse gases. Rapid and recent warming of the Arctic permafrost is resulting in significant greenhouse gas emission, both from physical and microbiological processes. The potential impact of greenhouse gas release from Antarctica is now also being investigated. In Antarctica, the McMurdo Dry Valleys comprise 10% of the ice-free soil surface areas in Antarctica and like the northern polar regions are also warming albeit from lower mean temperatures.
The work presented herein examines a comprehensive sample suite of soil gases (e.g., CO2, CH4 and He) concentrations and CO2 flux measurements conducted in the Taylor Valley during the Austral summer 2019/2020. Analytical results reveal the presence of significant concentrations of CH4, CO2 and He (up to 18,447 ppmv, 34,400 ppmv and 6.49 ppmv, respectively) at the base of the active layer. When compared with the few previously obtained measurements, we observe increasing CO2 flux rates (estimated CO2 emission in the study area of 21.6 km2 ≈ 15 tons day-1). The distribution of the gas anomaly, when compared with geophysical investigations, implies an origin from deep brines migrating from inland (potentially from beneath the Antarctic Ice Sheet) towards the coast beneath the permafrost layer. These newly obtained data provide a baseline for future investigations aimed at monitoring the changing rate of greenhouse gas emission from Antarctic permafrost, and the potential origin of gases, as the southern polar region warms.
A Random Forest approach to quality-chacking automatic snow-depth sensor measurements
Authors: Blandini Giulia , Avanzi Francesco , Gabellani Simone , Ponziani Denise , Stevenin Hervè , Ratto Sara , Ferraris Luca
Published: February 2023

Advanced environmental technologies have made available an increasing amount of data from remote sensing satellites, and more sophisticated ground data. Their assimilation into dynamic models is progressively becoming the most frequent, and conceivably the most successful, solution to estimate snow water resources. Models reliability is therefore bounded to data quality, which is often low in mountain, high-elevation, and unattended settings. To add new value to snow-depth sensor measurements, we developed a machine-learning algorithm to automatize the QA/QC procedure of near-surface snow depth observations collected through ground stations data. Starting from a consolidated manual classification, based on the expert knowledge of hydrologists in Valle D'Aosta, a Random Forest classifier was developed to discriminate snow cover from grass or bare ground data and detect random errors (e.g., spikes). The model was trained and tested on Valle d’Aosta data and then validated on 3 years of data from 30 stations on the Italian territory. The F1 score was used as scoring metric, being it most suited to describe the performances of a model in case of a multiclass imbalanced classification problem. The model proved to be robust and reliable in the classification of snow cover and grass/bare ground discrimination (F1 values above 90%), yet less reliable in random error detection, mostly due to the dataset imbalance. No clear correlation with single year meteorology was found in the training domain, and the promising results from the generalization to a larger domain corroborates the model robustness and reliability.This machine learning application of data quality assessment provides more reliable snow ground data, enhancing the quality of snow models.
The All-Hazards River Basin Governance Risk Assessment Strategy Under Covid-19 Pandemic Impact: A Social-Economic Vulnerability Case Study of Da-an River Basin Area in Central Taiwan
Authors: Hung Chi-Tung , Lin Wen-Yen , Lu Shao-Hsien
Published: February 2023

The past literatures regarding hazard risk cases and theories generally lack of risk-oriented spatial planning and dialogue, which induce so called “weakness policy” phenomena. The research contents and objectives of this study are to construct an all-hazards river basin governance index system under the impact of COVID-19 pandemic as the mean of research methodology, and applying AHP and GIS overlays as the analysis tools, to assess the disaster social-economic vulnerability and mitigation response on the case study site of Da-an river basin townships in central Taiwan. This study has found: 1) the noise and environmental pollutions caused by religion activities has decreased owing to the pandemic impact; 2) the Central Government’s "Stimulus Voucher" policy and tourists’ “retaliatory consumption” are benefiting local tourism industry under the pandemic.
Fine particulate matter (PM2.5) trends over China during 1980–2020 using MERRA-2 data
Authors: Yousefi Robabeh , Shaheen Abdallah , Wang Fang , Ge Quansheng , Wu Renguang
Published: February 2023

High levels of fine particulate matter (PM2.5) pose a severe air pollution challenge in China. In this talk, we present results of a comprehensive analysis of PM2.5 trends over China during 1980–2020 using the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2). The monthly mean PM2.5 concentrations of MERRA-2 show a good agreement with independent surface measurements across mainland China from 2013 to 2020. For the trend analysis, China was subdivided into six regions based on land use and ambient aerosols types. PM2.5 levels significantly increased over all regions during 1980-2020. Over the forest regions of China, significant increasing trends were observed in the northern (0.073 µg.m-3 per year) and northeastern (0.34 µg.m-3 per year) regions. In northwest China, PM2.5 experienced a significant increasing trend during 1980-2020 with a rate of 0.2 µg.m-3 per year. The Tibet region in southwest China also experienced a significant increase in PM2.5. Comparatively, the upward trends of PM2.5 were most pronounced in the eastern and southern regions with significant rates of 0.6 and 0.25 µg.m-3 per year, respectively. However, PM2.5 concentration trends changed from upward to downward around 2007 over the eastern and southern regions. The trend reversal around 2007 is mainly attributed to Chinese air pollution control measures.
Monitoring of agricultural drought using Crop Moisture Stress index and the estimation of resulting maize yield reduction
Authors: Živaljević Bransilav , Mimić Gordan , Blagojević Dragana , Marko Oskar , Brdar Sanja
Published: February 2023

The drought in south-eastern Europe in the summer of 2017 heavily affected agricultural production, subsequently decreasing yields of maize. The European Drought Observatory provides Combined Drought Indicator for a 10-day period with coarse spatial resolution of 5 km, which is not localized on field level. It is derived from the combination of Standardized Precipitation Index (SPI), the Soil Moisture Index Anomaly (SMA), and the anomaly of the fraction of absorbed photosynthetically active radiation (FAPAR). Monitoring moisture levels in crops can provide timely information about the presence of abiotic stress in plants and improper development within a growing season. Heat stress and low levels of moisture in maize during summer can thereafter have detrimental consequences on yield. For that reason, in this study, the crop moisture level was estimated at specific parcels by calculating the normalized difference moisture index (NDMI) from Sentinel-2 multispectral imagery during summer months (June–July–August) and the time-series of NDMI were analyzed. Based on the average NDMI value in July, the crop moisture stress (CMS) index was calculated and divided into six classes. Maize yield data on parcel level were provided by an agricultural company for the period 2017 – 2021 in the Backa region of Vojvodina province, Serbia. Yield data for the period 2017-2020 were used to calculate average yield for each class of CMS, whereas yield data from 2021 were used for validation. Mean absolute error (MAE) and root-mean-square error (RMSE) were calculated and were around 1 t/ha. The results showed that the CMS values at a specific parcel could be used for within-season estimation of maize yield and the assessment of drought effects. Also, the CMS index was tested for the 2022 growing season which had drought hazard conditions in south-eastern Europe according to the European Drought Observatory. Expected maize yield reduction estimated for specific scouted fields showed substantial and below average yield values.
Classifier-assisted level-based learning evolutionary search for heat extraction optimization of enhanced geothermal systems
Authors: Chen Guodong , Jiao Jiu Jimmy , Luo Xin
Published: February 2023

Enhanced geothermal systems are essential to provide sustainable and long-term geothermal energy supplies and reduce carbon emissions. Optimal well-control scheme for effective heat extraction and improved heat sweep efficiency plays a significant role in geothermal development. However, the optimization performance of most existing optimization algorithms deteriorates as dimension increases. To solve this issue, a novel surrogate-assisted level-based learning evolutionary search algorithm (SLLES) is proposed for heat extraction optimization of enhanced geothermal systems. SLLES consists of classifier-assisted level-based learning pre-screen part and local evolutionary search part. Specifically, the classifier-assisted level-based learning strategy employs probabilistic neural network as the classifier to classify the offspring into pre-set number of levels. The offspring in different levels uses level-based learning strategy to generate more promising and informative candidates pre-screened by classifier to conduct real simulation evaluations. In the local evolutionary search part, a surrogate model is constructed at the local promising area. The optimum of the surrogate model obtained by the optimizer is selected to conduct real simulation evaluations. The cooperation of the two parts is able to achieve balance between the exploration and exploitation during the optimization process. After iteratively sampling from the design space, the robustness and effectiveness of the algorithm are proven to be improved significantly. To the best of our knowledge, the proposed algorithm holds state-of-the-art simulation-involved optimization framework. Comparative experiments have been conducted on benchmark functions, a two-dimensional fractured reservoir and a three-dimensional enhanced geothermal system. The proposed algorithm outperforms other five state-of-the-art surrogate-assisted algorithms on all selected benchmark functions. The results on the two heat extraction cases also demonstrate that SLLES can achieve superior optimization performance compared with traditional evolutionary algorithm and other surrogate-assisted algorithms. This work lays a solid basis for efficient geothermal extraction of enhanced geothermal system and sheds light on the model management strategies of data-driven optimization in the areas of energy exploitation.
Soil moisture dynamic and desiccation effect of Robinia pseudoacacia plantation sequences in the loess hilly area
Authors: Han Fengpeng , Peng Weiping , Fei Hongyan , Li Yonghong
Published: February 2023

Soil moisture is the main factor limiting the revegetation and ecological restoration in the Loess Plateau region. Studying the change patterns of soil moisture across plantations is beneficial to the effective utilization of local soil moisture, meanwhile providing insights for scientific vegetation restoration. In this study, Robinia pseudoacacia (RP) plantations including 10, 15, 25, and 40 years (abbreviated as RP10, RP15, RP25, and RP40, respectively) were selected as the study objects, with the farmland (FL) and native grassland (NG) as controls. The variations of soil moisture and the intensity of soil desiccation at each site from 0–200 cm were analyzed in spring, summer and fall from 2015 to 2021. The results showed that the seasonal variation of precipitation had a strong influence on soil moisture, showing different degrees of lagging effect. The order of average soil moisture in seasons was fall > spring > summer and soil moisture in summer was significantly lower than that in fall and spring (p < 0.05). At depth, the vertical distribution characteristics of soil moisture were similar for RP plantations at the same season but varied within different seasons. The average soil moisture of RP plantations was significantly lower than that of FL and NG (p < 0.05) and showed a decreasing trend with the increase of stand age, which indicates that afforestation seriously increases soil moisture depletion. Furthermore, there were obvious soil drying layers in all RP plantations in different seasons, with the most severe intensity of soil drying in the 150–200 cm soil layer. This study highlights the long-term dynamics in soil moisture of RP plantations, providing insights for sustainable soil moisture use and rational land use management in the loess hilly areas of China.
Near surface muography studies at the Gallo-Roman archaeological site of Vienne, France.
Authors: Avgitas Theodore , Marteau Jacques
Published: February 2023

Archémuons is a collaborative project between the Institute of Physics of the 2 Infinities of Lyon (IP2I Lyon), the Laboratory of Geology of Lyon (LGL) and the ArchéOrient Laboratory. The three laboratories will perform surveys at the Palais du Miroir of the Gallo Roman Museum of Vienne in France. The goal of the project is to evaluate how geology surveys (electric resistivity, gravimetry, seismometry) synergize with muon tomography for near surface underground studies. The foundation of the Palais du Miroir building and the surrounding extensive network of galleries provide a rich yet challenging set of targets to investigate. The controlled/confined environment provides opportunities to test different analysis and imaging techniques as well as new detector geometries, scintillation materials and a new portable prototype compact detector that combines Cherenkov detection with a scintillator based trajectograph which will be deployed and tested on site. In November 2022 the project kickstarted with an electric resistivity survey of the surface above the gallery where the muon detector will be hosted. In parallel a first set of measurements was acquired with a small scintillation detector as a proof of concept and for a first evaluation of the ground overburden. We will present the current status of this project as well as a preliminary result acquired by the time of the EGU2023 General Assembly.
Global Water Resources and the Limits to Groundwater Use
Authors: Bierkens Marc
Published: February 2023

Humans have impacted the hydrological cycle since the invention of agriculture, but these impacts have grown to global proportions over the last 60 years. The indirect effects of anthropogenic climate change may be the largest, but the direct impacts by dam building, water withdrawals and the emission of pollutants is still formidable, even by comparison. In the first part of this lecture, I will briefly go over the impacts of human water use on global hydrology and water resources and how these impacts have been assessed by observational evidence and global hydrological models. This will also provide the opportunity to highlight some recent advancements in global hydrological modelling. The second part of the lecture will focus on the impacts of human water use on groundwater resources. After reviewing past assessments of global groundwater depletion rates, I will show results of ongoing research in our group on the limits to global groundwater use. These include: physical limits, related to groundwater-surface water interaction, permeability constraints and salinity; economic limits, related to the costs of groundwater extraction when wells become deeper; and ecological limits, related to the impacts of groundwater extraction on groundwater dependent ecosystems.
Interactive optimisation of 3-D subsurface models using potential fields
Authors: Anikiev Denis , Götze Hans-Jürgen , Plonka Christian , Schmidt Sabine , Bott Judith , Scheck-Wenderoth Magdalena
Published: February 2023

Modern workflows for construction of 3-D data-constrained Earth’s subsurface models in complex geological environments require sophisticated research software tools capable of handling interdisciplinary data and analysis in both visual and quantitative context. Integration of potential field data – gravity and magnetics – into the model building process is a key component that helps to bridge the gaps in the sparse input data by fitting the modelled response to the measurements. On the basis of IGMAS+ – a free cross-platform potential field modelling software – we show how 3-D model building can be complemented by interactive optimisation (inversion) of the triangulated subsurface model geometry. The optimisation is done by means of Covariance-Matrix-Adaptation Evolution Strategy (CMAES) which proved to be efficient for strongly non-linear problems with high-dimensional parameter space. In order to avoid topology distortions of the triangulated model domain, we use a concept of warping the space containing a model, rather than operating on the model vertices. The space warping implies an elegant solution using a system of virtual elastic springs connecting the lattice nodes. The optimisation workflow is demonstrated on synthetic and real case studies. We also show how an interpreter can interact with the process: visually control and influence the quality of the optimisation on a timeline. The proposed workflow is an efficient tool for automated quick model construction, validation and rebuilding, as well as for testing of multiple modelling hypotheses.
A parameter space for evaluating oceanic convection regimes
Authors: Legay Alexandre , Deremble Bruno , Penduff Thierry , Brasseur Pierre
Published: February 2023

Oceanic convection, parameterized through vertical mixing schemes, is still not well captured by ocean general circulation models. A preliminary step necessary to improve these schemes is to evaluate and compare how the models behave for different forcing regimes. Literature often proposes single-case comparison (either on a specific location or a specific time or with a specific metrics). The goal of our work is to propose a more systematic framework allowing evaluations and comparisons over a larger range of forcing regimes. For doing so, we define a parameter space which has been derived thanks to a theoretical 1D model of the mixed-layer depth (MLD) evolution. This parameter space is formed by two dimensionless numbers : λs which describes the relative contribution of the buoyancy flux and the wind in the surface layer, and the Richardson number Rh which characterizes the stability of the water column at the mixed layer base. In this presentation, I will highlight the key features of this parameter space and I will illustrate its physical robustness with an ensemble of 1D simulations. These simulations were conducted by applying a 10 years JRA55-do 1.4.0 atmospheric forcing within a 1D standalone code making use of the NEMO Turbulent Kinetic Energy + Enhanced Vertical Diffusivity (TKE + EVD) scheme. Then, I will present a test case to study the impact of the horizontal resolution on the convection regimes for a TKE + EVD scheme in 1D, 1°, 1/12° and 1/60° realistic NEMO simulations. I will define convective regimes by sorting the values according to the normalized evolution of the mixed layer depth dt MLD / MLD and I will show that these regimes are almost kept in the parameter space between 1D and 1° but become generally less convective / more restratifiying when increasing the resolution, highlighting the restratification processes by lateral fluxes. Moreover, I will show that the dynamics in the Mediterranean is much more affected by the increase of resolution than the Labrador sea, suggesting that it involves more intense lateral restratification processes.
Long-term changes in Carbon accumulation in mountain peatbogs in the South-West of Norway
Authors: Quintana Christian , Bjune Anne , Seddon Alistair , Lee Hanna
Published: February 2023

There is relevant research on temporal carbon accumulation changes, mostly in arctic permafrost peatlands in Norway, but little is known about the differences and comparisons with more oceanic and lower latitude peatlands in the region, where rainfall is one of the main climatic drivers. Climate projections in Norway for 2031-2060 and 2071-2100 show a rise in mean temperature and an increase of annual rainfall with more intense seasonal events in western, eastern, and northern parts. Under this rationale, this study hypothesizes that temporal variability of temperature and precipitation during the Holocene led to weaker and stronger evapotranspiration and moisture signals affecting local and regional vegetation in peatland ecosystems, water-table changes, and carbon accumulation capacity. This study will contribute to the generation of evidence of the roles and interactions of hydrology, temperature, vegetation, and land use changes on peatbogs carbon accumulation capacity during the Holocene. It will help to disentangle the responses of the carbon budget at different time scales. Methods involve the use of a set of proxies such as pollen, testate amoeba, LOI and bulk density to reconstruct the peat composition rate, organic matter, water table, and local (and regional) vegetation. A generation of an age-depth model and further multivariate analysis will allow to investigate the relationship between the proxies and carbon accumulation rate over the Holocene to further understand the temperature/precipitation correlation and the effects of a changing climate on the carbon budget.
Estimating soil water storage recovery under former planted forest on steep slopes in the semiarid area of the Loess Plateau
Authors: Wang Zhiqiang
Published: February 2023

Deep-rooted vegetation systems in the semiarid area of the Loess Plateau in China may result in deeper soil layers becoming depleted to unsustainable soil moisture levels. The main purpose of this study was to estimate water recovery in the 2-10 m soil layer once the initial deep-rooted vegetation was converted from forest to annual cropland and natural grassland under current climate conditions. Soil moisture at the 0-10 m depth of continuous crop and natural grass lands, crop and natural grass lands of former forest, and planted mature growing forest was measured repeatedly. The soil water storage of mature growing forest was set as the water recovery initial baseline, and that of continuous crop and grass lands were set as the upper limits for water storage recovery of crop and grass lands of former forest. The water recovery rate of annual crop land of former forest was 14.9 mm.yr-1, the total time needed for water to recover to present continuous cropland was 41.2 years. Results showed very little water recovery under natural grasses of former forest with the estimated water recovery rate being 0-2 mm yr-1. At such a minimal rate, the time necessary for the soil water levels to recover to present continuous natural grassland conditions would be 719.3 years. The results of this study indicate that a considerable period of time is necessary for soil water levels to recover in the Loess Plateau region once the soil has been depleted to a certain level. These types of condition may have long term environmental impacts which require further investigation to efficiently manage the water resources of this area.