bluuebunny/crossref_metadata_2025 huggingface dataset:
Modelled-based Photosynthetically Active Radiation climatology for Cyprus: Validation with measurements and trends
Authors: Fragkos Konstantinos , Fountoulakis Ilias , Nisantzi Argyro , Papachristopoulou Kyriakoula , Hadjimitsis Diofantos , Kazadzis Stelios
Published: February 2023

The visible part of the surface downward solar radiation (400 – 700 nm) known as Photosynthetically Active Radiation (PAR) is a key parameter for many land process models and terrestrial applications. More specifically, it is a critical ecological factor affecting agriculture productivity, ecosystem-atmosphere energy, CO2 fluxes, canopy architecture in forest ecosystems, and the growth of phytoplankton, among others. Despite its high importance, PAR measurements are rather scarce and no relevant worldwide radiometric networks for this quantity, in contrast with other actinometric quantities (e.g., global horizontal irradiance), exist. For these reasons, PAR levels are mostly estimated by satellite observations and modeling techniques.   In the current study, we present a 16-year PAR climatology over Cyprus, based on the combined use of radiative transfer (RT) models and satellite imagery. Copernicus Atmospheric Monitoring Service (CAMS) AOD and PWV, aerosol climatology of SSA and AE based on the MACv3 aerosol climatology, Ozone – OMI data for the period 2005 – 2021, are used as input to the RT model LibRadtran to obtain the clear sky PAR levels. Consequently, the CAMS Cloud Modification Factor based on MSG images will be used to derive the PAR under all sky conditions. The derived climatology has a spatial resolution of 0.05x0.05 degrees and a temporal variation of 15 minutes, as constrained by the availability of Seviri/MSG images. Finally, the quality of the retrieved climatology is assessed by comparison with ground-based PAR measurements and PAR retrievals from measurements of GHI through relevant conversion algorithms, from quantum sensors and pyranometers that are installed in selected stations of the Meteorological Service of Cyprus. Acknowledgments: 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. The Department of Meteorology of the Republic of Cyprus is acknowledged for providing ground-based data for validating the modelled quantities.
Evaluating the Turbulence Representation in a Numerical Weather Prediction Model over Mountainous Terrain
Authors: Goger Brigitta , Dipankar Anurag
Published: February 2023

The horizontal resolution of numerical weather prediction models (NWP) keeps decreasing towards the hectometric range. However, although topography, land-use, and other static parameters might be better resolved, the performance of physical parameterizations also has to be evaluated and assessed.One of the most challenging environments for modern NWP models is mountainous topography - namely because, among other issues, turbulence parameterizations were developed for horizontally homogeneous and flat terrain. This assumption is clearly violated in complex terrain, leading to the underestimation of the turbulence kinetic energy and an unrealistic representation of the mountain boundary layer.In this study, we perform limited-area simulations with the state-of-the-art NWP model ICON (Icosahedral Nonhydrostatic Model) across resolutions (1km, 500m, 250m, 125m) in the Inn Valley, Austria for a day where boundary-layer processes dominate. A thermally-induced valley wind circulation forms on this day, typical for wide valleys. The model is evaluated with observations from the CROSSINN measurement campaign, providing besides the usual meteorological parameters also measurements from LIDAR systems, radiosondes, turbulence eddy-covariance towers, and scintillometers. This data pool of observations allows us to evaluate the current turbulence parameterizations of ICON, starting with the (pre-)operational NWP resolution (1km) across the turbulence grey zone towards large-eddy simulation resolutions (125m). Both the one-dimensional (1D, Mellor-Yamamda type) and the three-dimensional (3D, Smagorinsky closure) turbulence schemes of the model compared with the observations across the grid resolutions to identify the resolution at which the 3D scheme starts to add value over the 1D scheme. Finally, we can check whether further improvements in the turbulence schemes are necessary for the turbulence grey zone.
Dynamically fragmented stream networks: field observations and physical drivers
Authors: Botter Gianluca , Durighetto Nicola
Published: February 2023

The flowing portion of river networks experiences never-ending event-based and seasonal expansion/retraction cycles, which mirror the unsteady nature of the climatic forcing.  These "temporary" rivers constitute a major fraction of the global river network, and are found across a variety of settings, especially in the headwaters. A dominant feature of these channel network dynamics is represented by the fact that the active streams are dynamically fragmented, i.e. they do not simply expand upstream when the catchment wets up, to dry down in the downstream direction during the recessions. Instead, the wetting/drying processes frequently happen in complicated spatio-temporal patterns, either activating disconnected reaches first, that will only eventually get connected to the main channel, or generating disconnections by drying out segments in the middle of the river network before the flow heads start retracting. This contribution analyzes the spatial patterns of local persistency along river networks (i.e. the fraction of time for which flowing water can be observed at each location, which is related to the wetting/drying order of the different reaches) combining field data on the spatiotemporal evolution of flowing channels and theoretical analyses, with the aim of elucidating the physical drivers of stream connectivity and disconnectivity in temporary streams. The analysis reveals that river fragmentation is related to the spatial heterogeneity of subsurface properties other than the contributing area (e.g. slope, local width, permeability). The proposed framework provides a clue for analyzing the impact of the spatial and temporal heterogeneity of streamflow presence for a variety of morphologic and biogeochemical processes (sediment transport, ecological dispersion and stream metabolism).
Automatic Detection of UAV GCP Targets Using Line-Based Approach
Authors: Yeom Junho , Javed Aisha , Kim Taeheon , Han Youkyung
Published: February 2023

With the advent and development of UAV technologies, UAV images are widely used in various fields since UAV photogrammetry has many advantages in terms of cost and accessibility. In addition, UAV photogrammetry has the advantage of enabling precise 3D surveying because it acquires images of higher spatial resolution with higher overlap compared to traditional aerial photogrammetry. UAV photogrammetry requires ground control points (GCPs) that are dense and evenly distributed throughout the study area. GCP surveying is generally conducted on-site, unlike automated UAV flight and image acquisition, which is a primary factor hindering time and labor cost reduction. In addition, pre-processing, such as UAV orthophoto, point cloud data, and digital elevation model (DEM) production, is performed automatically according to designated parameters, whereas matching GCP survey information with the images involves the intervention of an analyst. Therefore, in this study, the automatic extraction of UAV GCP targets and their centroids was investigated to increase the utilization of UAV photogrammetry and reduce the cost. Sequential steps of image thresholding, boundary detection, and buffered labeling detected a candidate area where ground targets exist. Then, the Hough transform was applied to the target candidates to extract two dominant lines and their intersection point representing the target center. The proposed method extracts the GCP targets from the images with high accuracy, and it was confirmed that it could be applied to complex urban areas. In addition, the GCP targets and their centroid points were successfully extracted from various land covers.
Anthropogenic sulfate-driven secondary organic aerosol formation over the eastern Himalayas through aqueous phase photochemical reactions
Authors: Deshmukh Dhananjay Kumar , Hegde Prashant , Sujakumari Arun Babu , Gogoi Mukunda M. , Babu S. Suresh
Published: February 2023

The ubiquitous presence of organic aerosols (OA) and their dominant role in climate forcing via direct and indirect effects are increasingly recognized. Among the large spectrum of OAs, water-soluble secondary organic aerosols (SOA) have gained considerable scientific interest due to the in-cloud formation process and consequent climate effects. However, a lack of consensus on the molecular fingerprints and formation pathways of SOA limits our ability to assess their climate impact globally.In this study, a detail investigation is made on water-soluble SOA components such as dicarboxylic acids, oxocarboxylic acids and dicarbonyls in springtime (March to May 2019) PM10 samples collected from a remote high-altitude site Lachung (27.4˚N and 88.4˚E, 2700 m a.s.l.) in the eastern Himalayas. The molecular fingerprints of water-soluble SOA components showed the predominance of oxalic acid (C2) followed by phthalic (Ph) and succinic acid. The diagnostic mass ratio of Ph to azelaic (C9) acid (2.1-7.7) indicated that anthropogenic emissions are the major sources of water-soluble OA at this remote high-altitude site. Moreover, SO42- dominates total water-soluble inorganic constituents and correlates significantly (R2 = 0.66) with the ISORROPIA-II model-derived aerosol liquid water content (LWC), indicating a crucial role of anthropogenic SO42- in controlling LWC of aerosols over the eastern Himalayas. Notably, we found significant positive relationships of C2 acid with both SO42- (R2 = 0.94) and aerosol LWC (R2 = 0.76), suggesting oxalic acid formation in LWC-enriched aerosols largely controlled by anthropogenic SO42- via aqueous phase photochemical processes. The increased formation of oxalic acid and related polar compounds with increasing SO42- is indicative of the fact that the reduction in anthropogenic emissions at the regional scale or source regions could control the water-soluble SOA loading in the atmosphere of the eastern Himalayas.
Effect of particle breakage caused by mechanical compaction on pore characteristics of sandstone: A DEM numerical simulation study
Authors: Jia Tong , Zhang Liqiang , Xu Zhenping , Chen Cai , Yan Yiming
Published: February 2023

Mechanical compaction is an important diagenesis of sandstone. Particle breakage commonly occurs during mechanical compaction, and plays a significant role in controlling the physical properties of the sandstone reservoir. However, existing experimental and numerical simulation methods have limitations in simulating mechanical compaction when considering particle breakage. In this study, a discrete element method (DEM) is purposed, which takes the maximum contact stress as the criterion of particle breakage and realizes particle breakage by particle cutting. Nine sets of numerical simulations were carried out with different breakage thresholds of reference particle (diameter = 6mm) and Weibull modulus. The parameters were calibrated according to the experimental data in published literature. On this basis, the compaction simulations of coarse sand with and without particle breakage were carried out, and the simulated vertical stress was 50Mpa. The results show that particle breakage caused by mechanical compaction significantly controls the porosity and pore structure. When the vertical stress reached 50 MPa, compared to the simulation results without considering particle breakage, the porosity difference rate caused by particle breakage was 4.63%; the radius difference rates of pores and throats were 2.78% and 6.8%, and the number difference rates of pores and throats were 4.95% and 8.74%, respectively. The simulation method can be used as an important technique in the study of sandstone diagenesis and is significant for revealing the formation process and mechanism of oil and gas reservoirs.
Comparison Of a Floating and a Bottom Fixed Tidal Turbine in a Coastal Marine Environment
Authors: Lewis Jack , Neill Simon , Poovadiyil Salim
Published: February 2023

The predictability and opportunity to provide baseload power has made tidal energy one of the most attractive marine renewable energy resources to help fight anthropogenic climate change. This has led to extensive research regarding the overall resource and methods of extraction. However, with differing designs found in today’s tidal turbine market, it is clear that there remains an ongoing debate as to where a tidal turbine should sit within the water column. In this study, a floating turbine and bottom mounted turbine, both based on current designs found in the market, were analysed over a tidal cycle in a 3D hydrodynamic model of the Morlais tidal test zone. The model was validated from ADCP measurements from the same area and recorded over the same tidal cycle. The aim was to establish the most efficient design and its effect on the surrounding water column. The results showed significant differences in the near-field effects of each turbine, but negligible effects were found further afield. Over the established tidal cycle, the floating turbine was found to be more efficient.
Course of human geography with climate change point of view
Authors: Hallanoro Laura
Published: February 2023

Climate change is an important theme which is addressed in many subjects nowadays in Finnish curriculum.  Young people are also very worried about and interested in climate change.  Understanding causes and effects of climate change is important as well is thinking about different ways to make a difference, what could be done and who should be doing it. Sustainable development is one important way of making the change towards cooler planet.I planned and held an online course of human geography with climate change point of view as part of a project Climate Change to Upper Secondary Schools. In this project three online courses were planned: 1,5 Degrees Life Skills for Young People, Human Geography (“in Climate Change Marinade”) and Climate Knowledge. The idea of online courses was to increase important future skills like critical thinking, problem solving, influencing the society, which would give strength to young people on their way to a better future.  My course Human Geography was the only one evaluated with a grade and directed only to older upper secondary school students. The other courses were evaluated only as approved or failed and they were open also to younger secondary school students.In my Human Geography course we studied the basics of human geography so that in every topic, were it population changes or natural resources, also how it is linked to climate change, was considered. Also, assignments that students did were linking together climate change and the topic studied.  During the time of corona pandemic part of students got accustomed to studying independently online, and interest in studying this way has increased. This is why, at least in Finland, online courses in schools seem to become more and more common. They are also cheap way to provide studying possibilities in a country where we have lot of small villages great distances apart one another.In my poster I’ll describe what kind of course my Human Geography was and how it was accomplished.
Methane emissions from abandoned hydrocarbon wells in Italy: inventory, measurement techniques and the role of mega-emitters
Authors: Procesi Monia , Etiope Giuseppe , Ciotoli Giancarlo , Moroni Monica
Published: February 2023

Abandoned hydrocarbon (oil and gas) wells (AOG) represent a poorly studied source of atmospheric methane, potentially contributing to total anthropogenic fossil methane emission and related climatic impact. Methane leakage from AOG was measured only in a few countries (U.S.A., Canada, the Netherlands, United Kingdom), and available inventories in other countries are incomplete or need quality checks. Methodologies for gas flux measurement are not standardized. New studies have recently started in Italy in order to inventory onshore AOG, design multiple and versatile techniques for methane flux measurement, which can be adaptable to different typologies of well-heads, and to execute first measurements. Preliminary data revealed the existence of several AOW releasing relevant amounts of methane (orders of 101 ton yr-1), which are up to two orders of magnitude above those typically observed in North America. Contextualization of such “mega-emitters” (their percentage with respect to total AOW, technical conditions, possible existence in other countries) is necessary to assess average emission factors and derive bottom-up methane emission estimates at national and global scale.
Impact from glacial rock flour on phytoplankton growth and the carbonate system
Authors: Bendtsen Jørgen , Daugbjerg Niels , Vallentin Larsen Kristina , Dyrberg Dahms Rasmus , Richardson Katherine , Rosing Minik
Published: February 2023

Glacial rock flour (GRF) is a felsic, silicate sediment that originates below the Greenland Ice Sheet, where the ice abrades basement rocks to a very fine powder. This is then transported by meltwater rivers or subglacial discharge into fjords and coastal waters. Thus, GRF is a naturally occurring component of the oceans around Greenland. The grain size of GRF typically ranges <1 - 100 µm with a median of 2-5 µm. The material behaves colloidally in water and distributions in fjords and coastal waters show that it has a residence time in the surface layer of up to several weeks. Glacial rock flour deposits are voluminous and common along the coast of Greenland and therefore it has the potential to be applied in geoengineering efforts on a global scale. The potential alkalinization from conservative cation release is estimated to be ~5,000 moles of alkalinity produced per ton of dissolved GRF. Additionally, GRF contains silica and phosphate that may contribute with macronutrients for phytoplankton growth together with various trace metals, e.g., iron and manganese. Hence, adding GRF to ocean surface waters has the potential to influence phytoplankton growth and, at the same time, increase alkalinity. However, the physical and chemical cycling of GRF in the water column, its implications for ecosystem services, and the chemical impact on the carbonate system are not well understood. The first results from incubation experiments with GRF in the field and from controlled laboratory experiments are presented here. Incubation experiments of GRF added to seawater collected in the Canary Current system showed a significant increase in photosynthetic activity during short term (~1 week) incubations. The positive influence from GRF on phytoplankton biomass and photosynthetic activity is also found in incubation experiments with a monoculture of a green planktonic alga and shows that trace metals mobilized within a few weeks have a significant positive effect on phytoplankton growth. Laboratory experiments of the settling rate of GRF show that the residence time is relatively long but also that flocculation of GRF particles, caused by salinity increases, may be an important process to consider in future field studies. Our results show that GRF has significant potential for increasing alkalinity, and that trace metals are mobilized from GRF in seawater, which can stimulate photosynthesis. We propose that GRF has the potential to impact ecosystem structure and increase biological productivity when applied to the ocean.
Open Source Application of Fusing Aerosol Products from GEO and LEO Satellites
Authors: Wei Jennifer , Zhao Sally , Gutkin Neil , Pan Xiaohua , Gupta Pawan , Levy Robert
Published: February 2023

Retrieving aerosol optical depths (AODs) from sun-synchronous polar orbiting (aka low earth orbit, LEO) satellites, such as MODISs, and VIIRSs, OMI, TROPOMI, etc,  has become well-established as a tool for extracting information on particulate matter (PM) and related processes in the atmosphere. However, with recently launched geostationary satellites (GEO), such as GOES-16/17/18,  and Himawari-8/9, and Meteosat Third Generation (MTG)   they provide a much higher temporal resolution (order of 10 minutes), typically an image once or more per hour during daylight compared to LEO once per day.  By combining these observations, we may be able to characterize the diurnal cycle of global AOD at the local, regional and global scale.  While the science community is still exploring the new data from GEO observations, we have been thinking about how to properly combine/merge/fuse those data considering differences in their spatial and temporal resolutions.  However, this poses a “Big Data” challenge. The big data challenge is not just about data storage,  but also about data discoverability,  and accessibility, and even more, about data migration/mirroring in the cloud-computing environment.   This paper is merely showing some of the efforts and approaches we have attempted in fusing six satellites’ Level 2 aerosol data (three are from GEO (GOES-16/17 and Himawari-8), and the other three are from LEO (TERRA/MODIS, AQUA/MODIS, SNPP-VIIRS) from Dark Target (DT) aAerosol rRetrieval aAlgorithm. Having the on-demand capability of fusing remote sensing products onto the desired temporal and spatial domain enables researchers and application practitioners to better manipulate and work with satellite and sensor data. It is our hopeWe hope that by making such an open-source package, and the accompanying functionality, the scientific community will be granted easier access to aerosol data processing resources.
Impact of organic amendments from date palm residues on water retention properties of two coarse texture soils
Authors: Le Guyader Elie , Morvan Xavier , Gommeaux Maxime , Miconnet Vincent , Marin Béatrice , Moussa Mohamed , Karbout Nissaf , Zoghlami Rahma Inès , Delgado-Iniesta María José , Intrigliolo Diego S.
Published: February 2023

The cultivated dryland soils of North Africa present low fertility and productivity due to low organic matter content (Brahim et al., 2021). Date palm residues are an abundant resource in these regions and only a minor part is recovered in oasian agroecosystems. The ISFERALDA project – Improving Soil FERtility in Arid and semi-arid lands using Local organic DAte palm residues – aims at developing the use of organic amendments based on traditional production (composting and slow pyrolysis) as a key tool to improve soil fertility and soil properties.The objective of this study was to quantify the effects of compost and biochar based on date palm residues on soil water retention. Two soils with properties similar to North Africa soils (sandy loam texture, alkaline pH, low organic matter content) were collected in a semi-arid Mediterranean area of southeast Spain. In addition, and in order to test further the influence of soil texture, soil sand content was artificially increased by supplementing the natural soils with washed quartz sand. The different types of organic amendments were tested at a dose of 60 t/ha (Edeh et al., 2020): compost alone, biochar alone and mixture of compost and biochar (50:50 in weight). Water content was measured using pressure membrane apparatus at nine different matric potential (pF), ranging from the saturation to the permanent wilting point.The results showed that water retention was higher in soil with organic amendments regardless of the pF and the soil type. For a specific soil, the addition of biochar alone or in combination with compost to the soil resulted in higher values than compost alone. The improvement in water retention properties was more pronounced for soils amended with sand. Thus, composting and/or pyrolysis of date palm residues is a viable alternative to improve the water retention properties of sandy and loamy soils. Keywords:Date palm – arid and semi-arid lands – organic amendments – soil water retentionReferences :Brahim, N., Karbout, N., Latifa, D., & Bouajila, A. (2021). Global Landscape of Organic Carbon and Total Nitrogen in the Soils of Oasis Ecosystems in Southern Tunisia. Agronomy, 11, 1‑17.Edeh, I. G., Mašek, O., & Buss, W. (2020). A meta-analysis on biochar’s effects on soil water properties—New insights and future research challenges. The Science of the Total Environment, 714, 136857. https://doi.org/10.1016/j.scitotenv.2020.136857
Simulating northern hemisphere glacier – ocean interactions using the Open Global Glacier Model and the Nucleus for European Modelling of the Ocean
Authors: Malles Jan-Hendrik , Maussion Fabien , Ultee Lizz , Kochtitzky Will , Copland Luke , Myers Paul , Marzeion Ben
Published: February 2023

Marine-terminating glaciers cover roughly one-third of the Northern Hemisphere's glacierized area (outside the Greenland ice sheet) and their direct freshwater export to the oceans has the potential to change not only global mean sea level (GMSL), but also local and regional ocean circulation patterns. Due to the interrelation of surface and frontal mass budgets, the dynamics of marine-terminating  glaciers are distinct from those of land-terminating glaciers forced only by the atmosphere. Here, were present recent advances in large-scale modeling of marine-terminating glaciers in the Open Global Glacier Model (OGGM). These include an enhanced representation of frontal processes and an independent calibration of surface and frontal mass balance. Further, we do a first investigation of coupling effects with an ocean general circulation model (Nucleus for European Modelling of the Ocean; NEMO). Including an explicit treatment of frontal processes (but so far ignoring future changes in ocean climate), we find that the spread between different emission scenarios at the end of the 21st century is reduced. Cumulative GMSL rise contribution projected for Northern Hemisphere glaciers is reduced by ca. 8 % in 2100, while the reduction for marine-terminating glaciers is ca. 23 %. Utilizing temperature and salinity output of NEMO, configured for the Arctic and Northern Hemisphere Atlantic (NEMO-ANHA4), to force a newly implemented submarine melt parameterization in OGGM, we estimate that 12 (6 - 22) % of the total frontal ablation was caused by submarine melt between 2010 and 2020. Finally, we explore differences in the ocean model’s output between runs that include the freshwater forcing from northern hemisphere glaciers and those that do not. The two main findings considering NEMO runs that include the freshwater forcing derived from OGGM output compared to those that do not are: i) an increased heat transport into Baffin Bay, and ii) changes in the pathways of Atlantic water to the Arctic Ocean, with less transport into the Barents Sea and more through Fram Strait.
Revisiting the volcanic forcing of high-latitude Northern Hemisphere eruptions
Authors: Fuglestvedt Herman , Zhuo Zhihong , Toohey Matthew , Krüger Kirstin
Published: February 2023

Large high-latitude explosive volcanic eruptions remain less well understood than their low-latitude counterparts, despite their potential for strong hemispheric climate impacts. Using the high-top coupled Earth system model CESM2-WACCM6 with prognostic stratospheric aerosols and chemistry, we simulate Pinatubo-magnitude Northern Hemisphere (NH) volcanic eruptions at 64° N. We show how the SO2 lifetime and growth of volcanic sulphate aerosols are strongly modulated by the initial state of the NH polar vortex for eruptions at this latitude. The resulting variability of the volcanic forcing is of comparable magnitude to its sensitivity to varying the plume composition, eruption season, and plume height. We compare the modelled volcanic sulphate deposition over the Greenland ice sheet to that assumed in current forcing reconstructions of past NH extratropical eruptions and provide a new model-based estimate of the magnitude and uncertainty of the transfer function used to reconstruct sulphur injections from such eruptions. Our results demonstrate the great potential for improvement in understanding and reconstructing the climatic impacts of NH high-latitude eruptions.
Molecular characterization of dissolved organic matter in groundwater of a coastal aquifer: microbial processing of sediment sourced organics
Authors: Zheng Yan , Zhang Peng , Wang Xuejing , Wang Yinghui , Li Hailong , Wang Junjian
Published: February 2023

Interest has grown in the land-ocean continuum as an energy and material exchange hotspot between the fresh water and saline water ecosystems, including its role in global carbon cycle. Despite progress, carbon cycle especially the biogeochemistry of dissolved organic carbon (DOC) in subsurface environment across the land-ocean continuum is inadequately illustrated. Using fluorescence spectroscopy and ultra-high-resolution mass spectroscopy, this study investigated the molecular characteristics of a broad array of dissolved organic matter (DOM) molecules in shallow groundwater from a coastal aquifer of Guangdong Province. A total of 21 groundwater samples were obtained from 5 multilevel monitoring wells (W1-W5) installed to depth 1 m – 13 m along a transect located 0 m to 65 m from the coast. The infiltration rate ranged from 0.79 to 23.51 m/d, possibly reflecting a less permeable layer between ~ 9 m to ~ 12 m depth. Above this layer consisted of clay lenses, salinity (3.93‰ - 32.43‰) decreases with depth, coinciding with a linear drop of ORP value from a high of +101 mV to a low of -131.90 mV at 8 m depth. The progressively more reducing condition with depth is likely fueled by DOM released from the clay, supported by simultaneous increases of DOC (0.46–2.36 mg/L), DIC (24.62–46.71 mg/L) and DIN (0.03–2.37 mg/L) concentrations and the fluorescence index (FI) with depth. Further, except for two samples (W3-13 m and W5-8 m) with low degradation index (IDEG) of 0.47 and 0.32, of the 11190 molecular formulae of DOM identified by ultra-high-resolution mass spectroscopy molecular formulae with high relative abundance (average ~86.0%) were present in the other 19 samples (90%), indicating the existence of a core pool of DOM compounds with similar molecular compositions despite a strong redox gradient and evidence for microbial processing based on fluorescence spectroscopy data. This core pool of DOM compounds displayed high IDEG (0.82±0.06), high %lignin-like DOM (85.9±2.6), and high abundances of carboxylic-rich alicyclic molecules (%CRAM: 69.5±3.4) that are generally considered to be refractory. Therefore, consumption of labile DOM is reasoned to have taken place, resulting in the prevalence of stable DOM in saline groundwaters of coastal aquifers. Key words: Coastal aquifers; Groundwater; Dissolved organic matter; 3D-EEMs; FT-ICR MS 
Super-resolution of digital elevation models using deep learning methods based on detrending
Authors: Wang Hongen
Published: February 2023

The digital elevation model (DEM) is an important basic data tool applied in geoscience applications. Because of its high cost and long development cycle of enhancing hardware performance, designing the related models and algorithms to improve the resolution of DEM is of considerable significance. At present, Neural networks (NNs) have demonstrated the potential to recover finer textural details from lower-resolution images by super-resolution (SR). Given similar grid-based data structures, some researchers have transferred image SR methods to DEM. These efforts have yielded better results than traditional spatial interpolation methods. However, the deep learning(DL) models need a lot of training data, and the model is difficult to converge, resulting in high training costs, which can be challenging. Therefore, in order to reduce the difficulty and cost of DL method training, we detrend the DEM data to decompose the target DEM into a deterministic low frequency trend part and a high frequency residual part. In the process of DL training, focus on the high-frequency part. We use multiple DL models and DEM data of various landforms to verify, and the experimental results show that our proposed method can indeed reduce the difficulty and cost of DL training. At the same time, our method can also be extended to other DL models.
MAX-DOAS Network in China and Its Applications
Authors: Liu Haoran , Liu Cheng , Xing Chengzhi , Hu Qihou , Tan Wei , Ji Xiangguang
Published: February 2023

Entering the “14th Five-Year Plan”, the coordinated control of PM2.5 and O3 has become a major issue of air pollution prevention and control in China. In order to achieve this goal, the stereoscopic monitoring of regional PM2.5 and O3 and their precursors (NO2, HCHO etc.) is extremely necessary. Yet, current monitoring networks are inadequate to monitor the vertical profiles of all above atmospheric compositions simultaneously, and to support air quality control. We have established a nationwide ground-based hyperspectral stereoscopic remote sensing network based on MAX-DOAS since 2015. This monitoring network provides a significant opportunity for the regional coordinated control of PM2.5 and O3 in China. One-year vertical profiles of aerosol, NO2, HCHO and O3 monitored from four MAX-DOAS stations (CAMS, SH_XH, SUST and CQ) installed in four megacities (Beijing, Shanghai, Shenzhen and Chongqing) are used to characterize their vertical distribution differences in four key regions of Jing-Jin-Ji (JJJ), Yangtze River Delta (YRD), Pearl River Delta (PRD) and Sichuan Basin (SB), respectively. The normalized and yearly averaged aerosol vertical profiles in JJJ and PRD exhibit a box shape under 400 m and a Gaussian shape, respectively, and they all show exponential shapes in YRD and SB. The NO2 vertical profiles in four regions all exhibit exponential shapes due to the obvious vehicle emissions. The shape of HCHO vertical profile in JJJ and PRD shows Gaussian, and it exhibits exponential shape in YRD and SB. The averaged O3 vertical profiles in four regions all exhibit box shape and linear shape in pollution and non-pollution periods, respectively. Moreover, a regional transport event occurred at an altitude of 600-1000 m was monitored in the southwest-northeast pathway of North China Plain (NCP) by five MAX-DOAS stations (SJZ, WD, NC, CAMS and UCAS) belonging to above network. The aerosol optical depths (AOD) in these five stations varied in the order of SJZ > WD > NC > CAMS > UCAS. The short-distance regional transport of NO2 in 800 m layer was monitored between WD and NC. As an important precursor of secondary aerosol, NO2 air mass in WD and NC all occurred 1 hr earlier than aerosol. Similarly, the short-distance regional transport of HCHO in 800 m layer between NC and CAMS, and it potentially affected the O3 concentration in Beijing. Finally, CAMS was selected as a typical site to learn O3-NOx-VOCs sensitivities in vertical space. We found the production of O3 changed from predominantly VOC-limited condition to mainly mixed VOC-NOx-limited condition from 0-100 m layer to 200-300 m layer. In addition, the downward transport of O3 could make a contribute to the increase of ground surface O3 concentration. ground-based hyperspectral stereoscopic remote sensing network provide a promising strategy to support PM2.5 and O3 and their precursors management and attribution of sources.
Climate influences of Asian anthropogenic aerosols decomposed using a Reduced Complexity Model
Authors: Stjern Camilla Weum , Samset Bjørn Halvard , Wilcox Laura , Joshi Manoj
Published: February 2023

Aerosol emissions have a wide range of impacts on the climate both near to and far from emission sources. Impacts span from local changes in surface solar warming to large-scale modifications of atmospheric circulation patterns and monsoonal precipitation. They have also been found to have an outsized near-term influence on extreme events in recent climate model studies. Consequently, future aerosol emission changes are likely to contribute to climate related risk in many highly populated regions, some of which are particularly vulnerable, for instance, to shifts in precipitation patterns or timing with respect to growing seasons. However, aerosol climate impacts generally follow patterns and time evolutions that are markedly different to those from greenhouse gas driven global surface warming, and our understanding of them is still plagued by high scientific uncertainty.Given the urgent need for improved knowledge about the near-term influences of changes in aerosol emissions, we here introduce SyRAP-FORTE – a tool for understanding and decomposing the local and remote climate effects of regional aerosol emissions. SyRAP – a set of Systematic Regional Aerosol Perturbations – is developed using FORTE2.0, a Reduced Complexity (RC) climate model developed in the UK. Current and expected future aerosol emission changes are particularly strong in East and South Asia, where high population densities imply high potential climate risk. In the initial version of SyRAP, presented here, we therefore perturb absorbing and scattering aerosols, separately, over India and East China, to assess their separate influence on local responses in a range of climate parameters.We document and validate the climate responses in FORTE to the regional aerosol perturbations, showing for instance that removing emissions of absorbing aerosols over both East China and will cause a local drying, but a range of more widespread effects. We find that SyRAP is able to reproduce the overall aerosol responses documented in the literature, and also that it allows us to decompose the influences of different aerosol species from the two regions on the climate near to, and far from, the emission sources.Finally, we show how SyRAP can be used as input to emulators and tunable simple climate models, and as a ready-made tool for projecting the effects of near-term changes in Asian aerosol emissions.
A new modeling method to quantify aerosol-induced vegetation-climate biophysical feedbacks
Authors: Zhang Yuan , Ciais Philippe , Li Laurent , Boucher Olivier
Published: February 2023

Atmospheric aerosols can strongly affect vegetation through their cooling effect and changing diffuse radiation. The changes of vegetation further alter the climate through biophysical and biochemical feedbacks. Previous studies either investigate aerosol impacts in offline simulations to understand the vegetation response, or in fully coupled simulations to quantify the full impacts on the climate, including through atmospheric physics. So far there has been no experiment designed to separate the aerosol-induced vegetation-climate feedback from the aerosol impact itself. Existing studies on vegetation-climate feedbacks (not necessarily due to aerosol) often prescribe vegetation properties, so that the climate altered by vegetation can no longer affect the vegetation, leading to an incomplete feedback estimation. To quantify the full vegetation-climate feedback due to aerosols, we propose a new modeling framework in coupled Earth system models (ESM). In this new framework, the atmosphere module simulates the climate under both preindustrial and historical aerosol scenarios at each time step. The climates simulated under the two scenarios are both passed to the land surface module. All processes in the land surface module are separated into an organic (vegetation, part of soil) and an inorganic (energy budget, hydrology) part. The organic part is driven by the preindustrial aerosol climate, while the inorganic part is driven by the historical aerosol climate and affected by the organic part. The land surface processes provide the feedback variables for atmosphere to simulate the next time step. The feedback can be evaluated by comparing this experiment to fully coupled simulations under preindustrial and historical aerosol scenarios. Here we first introduce this framework and apply it to IPSL-CM6A-LR ESM. This new framework can have more general usages and provide opportunities to understand the land surface feedbacks in the Earth system.
Groundwater flow changes in response to extensional earthquakes: a case study from the 2016-17 seismic sequence in Central Italy
Authors: Cambi Costanza , Mirabella Francesco , Petitta Marco , Banzato Francesca , Beddini Giulio , Cardellini Carlo , Fronzi Davide , Mastrorillo Lucia , Tazioli Alberto , Valigi Daniela
Published: February 2023

Changes in groundwater flow in response to strong earthquakes are widely described in many tectonic environments. For example, a post-seismic discharge variation is often attributed to an increase of bulk permeability due to co-seismic fracturing and/or to a change in the role of faults in acting as conduits/barrier to groundwater flow.We take as an example the fractured aquifer of the Mts. Sibillini carbonate massif, in Central Italy, which were affected by a strong and prolonged extensional seismic sequence in 2016-17. The sequence was characterized by an M=6.5 event (mainshock), an M=6 event, an M=5.9 event, up to 60 M>4 events and several M>5 earthquakes. The strongest events caused rupturing of the topographic surface for a cumulative length in the order of 30 km and an important portion of aftershocks occurred at depths where groundwater is stored.As a response to the seismic sequence, the main NNW-directed groundwater flow was diverted to the west and a discharge deficit was observed at the foot-wall of the activated fault system with a relevant discharge increase, accompanied by geochemical variations, at the fault system hanging-wall.By integrating geo-structural reconstructions, seismological and ground deformation data, artificial tracer tests results and a 4-years discharge and geochemical monitoring campaign data, we show that the observed groundwater variations are due to a combination of permeability increase along the activated fault systems and hydraulic conductivity increase of the hanging-wall block due to fracturing, extension and subsidence, which determined a fast aquifers emptying. Seismicity temporarily triggered a change of the pre-existing predominant along-faults-strike NNW-SSE oriented regional flow to a west-directed flow, perpendicular to faults strike. We discuss the position of the aquifer with respect to the activated faults and how this affected the observed phenomena. REFERENCECambi, C., Mirabella, F., Petitta, M., Banzato, F., Beddini, G., Cardellini, C., ... & Valigi, D. (2022). Reaction of the carbonate Sibillini Mountains Basal aquifer (Central Italy) to the extensional 2016–2017 seismic sequence. Scientific Reports, 12(1), 1-13. DOI: 10.1038/s41598-022-26681-2
The impact of fault surface 3D geometry on risking fault reactivation
Authors: Aleksans Janis , Childs Conrad , Schöpfer Martin
Published: February 2023

The reactivation of faults can occur when the effective stresses acting on them are perturbed. In some cases man-made changes in effective stress can result in fault reactivation that can have enormous impacts including loss of integrity of underground storage facilities. Current practical methods for making this assessment are generally based on shear stresses calculated over fault surfaces. Depending on the absolute or relative magnitudes of these resolved shear stresses, which depend primarily on the local orientation of the fault surface relative to the regional stress field, different faults or parts of faults are said to be closer or further from the Coulomb failure envelope and are therefore more likely to slip due to changes in effective stress. This proximity to failure/slip is referred to as the slip tendency or reactivation tendency.Although the slip/reactivation tendency approach is firmly grounded in Coulomb theory and laboratory experiments, there may be issues applying it to the reactivation of irregular fault surfaces. A key assumption of the approach is that an area of a fault surface can be treated in isolation so that the slip tendency can be evaluated once its orientation and frictional properties are known. However, it is well established that fault surfaces are not planar but often have highly irregular geometries and fault rock distributions so that the likelihood that a particular part of a fault will reactivate must also depend, not only on the properties at that point but also on adjacent areas of the fault surface.To investigate the significance of fault surface irregularity for the evaluation of fault slip/reactivation tendency, we conduct numerical modelling of fault reactivation resulting from an increase in pore pressure within a normal faulting stress regime. The modelling employs a form of the Discrete Element method that uses rigid blocks. This approach provides for both accurate representation of the geometry and frictional properties of the irregular slip surfaces and also failure in the surrounding wall-rock and is capable of modelling the variety of ways in which slip may initiate on, or adjacent to an irregular fault.
Thermodynamic and Topology path equations, Multiphase flow in porous media with Steiner’s Formula & Lagrangian Mechanics
Authors: Liu Che You , Hsu Shao Yiu
Published: February 2023

In recent years, scientists & physicists faced a question about the macroscope boundary condition interacting with the capillary pressure related to fluid topology. How to integrate the relationship of mechanics between thermal physical quantities (e.g free energy, entropy, & pressure) and fluid topology variables (e.g surface area, mean curvature, & Euler-Characteristic) play a main role in Continuum Mechanics research on low Reynold number flow in porous media in the future. As well, developing the theory approach is our research purpose. The perspective of Newton's Mechanics can not fit the demand of dealing with multiphase porous media flow with a lot of complex and unknown constraints and cross-scoping variables. To build up the dynamic model containing the topology states for multiphase flow in porous media, we introduced two concepts to cross the barricade of Newton mechanics applying to multiphase porous media flow, the generalized coordination and Lagrangian mechanics based on Hamilton’s Principle (The Least Action Principle). The principle shows that any physical quantity changing path making the “Action” as a function(Lagrangian integration) of generalized coordination is holding the minimum. Lagrangian mechanics is widely used in many other frontal research regions depending on the Lagrangian quantity design and generalized coordination setting, including dynamical Structure Analysis, Automatic control theory, electrodynamic and Standard Models in Particle Physics.

We provide the approach from Lagrangian mechanics to describe the thermodynamic and topology changing path during the multiphase flow process. This study recognized the topology state variable as generalized coordination. Furthermore, the Lagrangian quantity and dissipation terms were designed in this research with the kinetic energy, Landau potential, and Rayleigh dissipation function. We combined Steiner’s formula as fluid geometric constraint, dissipation system, and Lagrangian Mechanics to develop the evolution dynamic equations for fluid topology properties. Then we derive the geometrical conservation equations for the topology state variables during the whole dynamics process. Also, the derivation of Darcy’s law finished from Lagrangian mechanics under saturated and steady conditions.

 