bluuebunny/crossref_metadata_2025 huggingface dataset:
Remote sensing of trace gases with Chinese satellite instruments
Authors: Liu Cheng , Zhang Chengxin , Su Wenjing , Hu Qihou , Zhao Fei , Li Ziwei , Xing Chengzhi , Liu Haoran , Tan Wei
Published: February 2023

Remote sensing from hyperspectral satellite instruments, such as OMI, TROPOMI and OMPS, can simultaneously obtain the spatio-temporal distribution of several species of trace gases, which has been widely used to study the emissions, regional transport and physical and chemical evolution of trace gases. Nevertheless, there were very few relevant studies using Chinese satellite instruments, because the poor spectral quality makes it extremely difficult to retrieve data from the spectra of the Environmental Trace Gases Monitoring Instrument (EMI), the first Chinese satellite-based ultraviolet–visible spectrometer monitoring air pollutants. In this study, we performed on-orbit wavelength calibration to calculate daily instrumental spectral response functions (ISRFs) and wavelength shifts to diminish the fitting residuals. For the retrieval under the low signal-to-noise ratio (SNR) of EMI, an adaptive iterative retrieval algorithm is set up to select the retrieval setting best with minimum uncertainty. Besides, we used simulated irradiance instead of measured irradiance to obtain the requisite daily solar spectrum for the following retrieval algorithm, because EMI only provides the solar spectrum once every six months. Through these algorithm updates, several trace gases, such as Ozone (O3), nitrogen dioxide (NO2), sulfur dioxide (SO2) and formaldehyde (HCHO), were retrieved from EMI with comparable accuracy of OMI and TROPOMI. The retrieval results from EMI were used to locate emission sources, evaluate regional transport and trace the change of air quality due to important events, such as COVID-19 pandemic, China International Import Expo and Beijing Winter Olympic Games.
Combining Landsat-8 and Sentinel-2 to investigate seasonal changes of suspended particulate matter off the abandoned distributary mouths of Yellow River Delta
Authors: Li Peng , Chen Shenliang
Published: February 2023

Suspended particulate matter (SPM) is the primary component of coastal waters. The spatiotemporal dynamics of SPM has an important influence on water bio-optical properties, pollutant diffusion, landform evolution, and carbon, oxygen, and nutrient cycles. This study presents the spatial distribution of monthly average SPM concentrations from 2017 to 2020 in the abandoned Diaokouhe and Shenxiangou distributary mouths of the Yellow River Delta (YRD). The SPM concentrations were derived based on 161 Landsat-8 OLI and Sentinel-2A/B MSI satellite images. Accuracy assessment using the synchronous in-situ measurements (R2= 0.91, root mean square error (RMSE) = 38.79 mg/L, and relative percentage difference (RPD) = 23.45%) and cross comparison between SPM concentrations derived from the two sensors (R2= 0.97, RPD = 8.77%) showed convincing performances. Our results show that the monthly average SPM is characterized by significant seasonality, with a higher concentration and wider range in dry seasons compared to that in wet seasons. The spatial distributions of SPM are closely associated with coastal water depths. The SPM concentration in the Shenxiangou mouth is always lower than that of the shallower Diaokouhe mouth. The long-term seabed erosion provides a continuous supply of sediment. Wind-wave forces explain the seasonal variations of SPM by inducing the resuspension of bottom sediments. The residual currents control the transportation of SPM to the offshore and to the east. The artificial groins located between the two river mouths show obvious sediment trapping effects. Moreover, the interception capability of impermeable groins is considerably better than that of permeable groins.
The long-term effects of elevated atmospheric CO2 and warming on soil microbial communities in a tidal marsh ecosystem
Authors: Yang Yerang , Lee Jaehyun , Noyce Genevieve , Megonigal Patrick , Kang Hojeong
Published: February 2023

Tidal marshes are an important transition zone connecting marine, freshwater, and terrestrial ecosystems. Tidal marshes are known to be sensitive to global climate change such as elevated CO2 and warming. In particular, it is yet to be revealed whether the such change may increase or decrease carbon stock in tidal marshes. Although soil microorganisms play an important role in carbon storage in tidal marshes by determining carbon mineralization, little is known about the interactive effects of elevated CO2 and warming on soil microbial communities in field conditions. Here, we elucidate the effects of 6-year experiment of climate manipulation on soil microbial communities in a tidal marsh. The manipulation experiment included 4 treatments of 1) elevated atmospheric CO2 concentrations (750 ppm) only, 2) warming (+5.1 °C) only, 3) both elevated CO2 and warming, and 4) ambient conditions. Elevated CO2 significantly changed the structure of the RNA-derived (active) and DNA-derived (total) soil microbial community, but warming did not affect either. The relative abundances of Acidobacteria, Actinobacteria, Chloroflexi, and Planctomycetes were higher in the DNA-derived soil microbial communities than in the RNA-derived soil microbial communities, whereas those of Campilobacterota, Desulfobacteria, Gammaproteobacteria, Myxococcota, and Spirochaetota were higher in the RNA-derived soil microbial communities. In addition, elevated CO2 changed the microbial communities from r- to K-strategists in both RNA and DNA-derived communities, suggesting that this may offset additional C input by roots in a future elevated atmospheric CO2 environment. This study provides a better understanding of microbial response to the combined effects of elevated atmospheric CO2 concentrations and global warming in the tidal marsh ecosystems.
Application of Electrical Resistivity Tomography for Assessment of Slope Creep Vulnerability
Authors: Bong Taeho , Im Sangjun , Seo Jungil , Kim Dongyeob , Heo Joon
Published: February 2023

Slope creep is a mass movement characterized by the slow, downward progression of rock and soil down a low grade slope. One of the causes of slope creep is the expansion of materials such as clay. Expansive clay is a soil that is susceptible to swelling and shrinking when they are exposed to water. However, it is not easy to find out if those vulnerable zones exist in soil slopes. Recently, the electrical resistivity survey has been widely used to determine the spatial and temporal variability of soil properties. In this study, field and electrical resistivity surveys were conducted in order to assess the vulnerability of slope creep. In the field surveys, various factors known to affect slope creep, such as soil types, physical and hydraulic properties of soils, gradient, topography, geological characteristics, and forest vegetation, were investigated, and traces of slope creep, such as tension cracks or tilted trees, were also observed. From the results of the field survey, slopes were divided into two groups: a group with a high creep vulnerability and a group with a low creep vulnerability. Then, electrical resistivity tomography was applied to assess the possibility of slope creep. Various statistical properties for soil resistivity values were calculated, and the most suitable criterion to distinguish the two groups for slope creep vulnerability was identified based on the t-test (p-value). In conclusion, there was a statistically significant difference (p-value=0.003) between the two groups when classified as a ratio of soil resistivity of 400Ω·m or less, and these results indicated that it is possible to identify slope prone to creep using the electrical resistivity survey.Acknowledgments: This work was supported by Korea Association of Forest Enviro-conservation Technology (KAFET) and the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. 2022R1A2C4002583).
Spatial variations in the sea ice-mixed layer depth relationship in the West Antarctic Peninsula
Authors: Bischof Milo , Goldberg Daniel , Henley Sian , Fraser Neil
Published: February 2023

The impacts of upper-ocean mixing on primary productivity are complex and range from an entrainment of nutrients to modulating light limitations. Sea ice in turn plays an important role in determining mixing conditions through its cycles of formation and melt, and by moderating wind forcing. With sea ice conditions in the Southern Ocean projected to undergo large changes over the course of the century, understanding the relationship between sea ice and upper-ocean mixing is crucial for understanding the impacts of climate change on biological production in this region. Due to the inaccessibility of sea ice-covered waters however, mixed layer depth observations are often not available at a high temporal and spatial resolution. Here we present an analysis of sea ice-mixed layer depth relationships during a 40-year regional ocean-sea ice simulation of the  West Antarctic Peninsula (WAP) and Bellingshausen Sea, a highly biologically productive region of global importance. The relationship between winter sea ice and spring mixed layer depth shows clear differences on and off the WAP continental shelf, with decadal variations in the location of the boundary between negative and positive correlations. Potential mechanisms causing this effect are considered in detail, including the nonlinear relationship between sea ice cover and turbulent mixing, the transport of sea ice within the region, and a difference in the timing of the sea ice seasonal cycle between the two regions. The transport of warm Circumpolar Deep Water onto the shelf is also discussed. The presented findings have implications for the spatial distribution of primary producers in a more ice-free future WAP.
XAIDA4Detection: A Toolbox for the Detection and Characterization of Spatio-Temporal Extreme Events
Authors: Cortés-Andrés Jordi , Gonzalez-Calabuig Maria , Zhang Mengxue , Williams Tristan , Fernández-Torres Miguel-Ángel , Pellicer-Valero Oscar J. , Camps-Valls Gustau
Published: February 2023

The automatic anticipation and detection of extreme events constitute a major challenge in the current context of climate change, which has changed their likelihood and intensity. One of the main objectives within the EXtreme Events: Artificial Intelligence for Detection and Attribution (XAIDA) project (https://xaida.eu/) is related to developing novel approaches for the detection and localization of extreme events, such as tropical cyclones and severe convective storms, heat waves and droughts, as well as persistent winter extremes, among others. Here we introduce the XAIDA4Detection toolbox that allows for tackling generic problems of detection and characterization. The open-source toolbox integrates a set of advanced ML models, ranging in complexity, assumptions, and sophistication, and yields spatio-temporal explicit detection maps with probabilistic heatmap estimates. We included supervised and unsupervised methods, deterministic and probabilistic, neural networks based on convolutional and recurrent nets, and density-based methods. The toolbox is intended for scientists, engineers, and students with basic knowledge of extreme events, outlier detection techniques, and Deep Learning (DL), as well as Python programming with basic packages (Numpy, Scikit-learn, Matplotlib) and DL packages (PyTorch, PyTorch Lightning). This presentation will summarize the available features and their potential to be adapted to multiple extreme event problems and use cases.
Intraseasonal influence of the North Atlantic-East and North Asia pattern on TP summer land surface energy budget
Authors: Fan Weiwei , Hu Zeyong
Published: February 2023

Analysis of the multi-scale variation characteristics of the land surface energy budget and its causes over the Tibetan Plateau (TP) is helpful to deepen the understanding of local land-air interaction and its climate effects. Based on daily atmospheric reanalysis data during the period of 1981-2018, the intraseasonal impacts of the North Atlantic-East and North Asia (NAENA) teleconnection pattern on TP summer land surface energy budget and the associated mechanism are studied. NAENA is the second mode of 200-hPa meridional wind anomalies over the Eurasian continent, which has significant effects on the multi-scale climatic variability in Eurasia. Composite analysis showed that the NAENA pattern can significantly affect land surface energy budget anomalies in TP by regulating the atmospheric circulation anomalies over and around the TP. On day 0 of positive-phase NAENA events, there is a cyclone to the west of TP, which can lead to anomalous vertical ascending (descend) motion and convergence (divergence) over the lower atmosphere of the northeast (southwest) of the TP. Moreover, it can result in an anomalous increase (decrease) in cloud cover, contributing to weakened (enhanced) downwelling surface shortwave radiation flux and enhanced (weakened) downwelling surface longwave radiation flux, and leading to an anomalous weakening (enhancement) in surface sensible heat flux over the northeastern (southwestern) TP.
Investigating the quality of radar composites in a mountainous region in northeastern Thailand
Authors: Mapiam Punpim Puttaraksa , Methaprayun Monton , Jotisankasa Apiniti , Bogaard Thom
Published: February 2023

Composite radar products are made by combining radar scans of multiple radar stations into a single product to improve the quality of the radar product in overlapping region and to visualize the distribution and movement of precipitation over a large area. The reliability of radar composites depends on radar data quality, as each radar measurement is influenced by, among others, atmospheric conditions, interference with other sources, and the radar specifications. The quality of rain radar composites is critical as these products will be used for near real-time forecasting of hydrometeorological hazards. This research aims to investigate the controlling factors influencing the quality of radar composites over a hazard-prone mountainous region in northeastern Thailand. In this study we evaluate and quantify the rain radar composites by looking at four quality indexes among the distance to the radar station (DTR), the height of the beam above the ground (HTG), the radar beam blockage fraction (BBF), and the radar reflectivity fraction between the composited radar stations (RRF). For our overarching research to build a near real-time forecasting system for landslide and flashflood warnings in the Khao Yai National Park, Lamtakong basin and surroundings. Hereto, local cells of high intensity precipitation should be derived with highest accuracy. Two rain radar stations were selected: Sattahip, 220 kilometer southwest and Phimai, 140 kilometer North of the Lamtakong basin. Automatic rain gauges in the overlapping area were used to evaluate the radar composite product during storm events in 2020. The results indicated that specific quality indexes could be used to identify areas with inaccurate or unreliable raw data. This was a particular advantage in areas where the radar beam was (partly) blocked by an obstacle and underestimated the intensity of the storm. The BBF was the most important quality index in the study area. Moreover, combining the BBF with the RRF could increase the accuracy and reliability of radar rainfall estimates. Overall, using radar composites with raw radar data quality control can play an essential role in improving near real-time nowcasting for further natural hazard mitigation in the mountainous area.
Apply iTilt-Euler method on the magnetic anomaly at southwest of Penghu.
Authors: Hsu Ching , Hsu Shu-Kun , Lo Chung-Liang
Published: February 2023

By checking the magnetic data measured from New Ocean Reacher 3 at 2020/9/21 to 29, we can easily find that there are two anomalies localized south-west of Penghu. In the west, it is located around 119.08°E, 23.46°N and with defect amount 620 nT. The other site is located at 119.34°E, 23.45°N but not as solid as the first one (340 nT).To understand the magnetic structure below these two sites, this study will use the iTilt-Euler method as the primary method for calculating the depth of these two magnetic anomalies. Before applying iTilt-Euler method, I’ll calculate total horizontal gradient and only use “quality of local maximum” larger than 3 to make sure the input data are around the edge of the source. Following the iTilt-Euler method, we will use the zero-order analytical signal as a constraint to select solutions that are above the structure. Finally, we will use the average of the selected solutions representing the properties of this anomalous site.After going through the whole process, we discovered that the structure of the western site could be the fault with the top 0.88 km depth and the mean structural index 0.23. And the other site could be the dike, which is 1.8 km depth and has an average structural index of 1.4.
Link between orographic gravity wave parameterizations and resolved dynamics in CMIP6 models.
Authors: Hájková Dominika , Šácha Petr , Pišoft Petr
Published: February 2023

Internal gravity waves (GWs) have an important influence on the atmospheric energy transport and momentum budget. Consideration of the GWs – related processes is necessary in modelling and conceptual models of the atmosphere. GWs cover a broad spectrum of wavelengths from few to thousands of kilometres. Hence, they cannot be fully resolved by the global climate models (GCMs) and have to be parameterized. Although recent efforts with satellite observations and high-resolution models have been improving tuning and constraints of the GWs parameterizations, there is still a large uncertainty concerning the effects of GWs in GCMs. This is unwanted due to large impact of GWs on the atmospheric dynamics.In our research we focus on orographic GW (OGW) parameterizations used in CMIP6 simulations. We compare the OGW induced drag from 7 different OGW parameterizations used in 9 different models, establishing the simulation-unique tuning of free parameters for majority of them. The comparison shows large, unexpected differences between simulations, which can be partly traced to the tuning or type of the parameterization. We also analyze intermodel differences in zonal mean winds and Eliassen-Palm flux divergence to trace the effects of the differences in OGW drag. Particularly, our results demonstrate a strong correlation between resolved wave drag and OGW drag in the models. Overall, our study gives an additional motivation for further improvements of the OGW parameterization schemes, with the aim of lowering the uncertainty of the future climate projections.
Trials and design iterations experienced developing a low-cost depth trawl to sample macroplastic through the water column of a tidal river.
Authors: Higgins David , Correia Renata , Kang Hooi Siang , Quen Lee Kee , Ken Tan Lit , Vollering Andre , Pinson Stijn , H. Assumpção Thaine , Mani Thomas
Published: February 2023

Understanding the transport behaviour of mismanaged plastic waste in riverine and estuarine environments is growing. However, many studies to date focus on the surface layer transport while a limited number look to measure the vertical distribution of plastic waste within these systems. Factors such as density, shape, the influence of wind and flow velocity can determine the vertical distribution of the plastic waste in a river, but many knowledge gaps remain. With this, and as technology developers move to create innovative river surface focused interception solutions to extract plastic waste, a greater understanding of the transport behaviour of sub-surface plastic debris is required. Here, we present a comprehensive overview of the development stages required to build and deploy a low-cost depth trawl tool designed to sample plastic waste at a depth of up to 5m in a heavily polluted river in Malaysia. Topics covered include tool design concepts, manufacturing methods, onsite testing, river deployment learnings and sampling results. Field data is compiled from over 60 sampling surveys conducted over 14 days in several locations along the Klang River, Malaysia. The depth trawl is mounted to a locally available fishing boat (sampan) and consists of two steel horizontal arms, a steel frame, two winches, cables, weights, five nets, and is operated manually with the assistance of a solar-powered motor. The dimensions of each net are 30cm (W) x 50cm (H) x 100cm (L) with a mesh size of 30mm x 30mm. To ensure that the nets remain aligned vertically during deployment, a weight of 15kg is tied to the bottom of the net system on both sides. Samples were collected every 1 metre to a depth of 5 metres. Each sampling was conducted for 15 minutes, six times per day with an interval of 1 hour between samples to allow for changes in the tide and river flow direction. An ADCP was deployed in parallel to the depth trawl to provide measurements of flow velocity variation at the river surface and with depth. In addition, this paper reviews the depth trawl system’s capabilities and recommendations for further studies and applications in the field.
Influence of the Wind Stress Curl on the Eddy Saturation Behavior of the ACC in a Barotropic Perspective
Authors: Dogan Sima , Muller Caroline , Nadeau Louis-Philippe , Venaille Antoine
Published: February 2023

The size of zonal transport of the Antarctic Circumpolar Current (ACC) is almost independent of the variations in westerly winds over the Southern Ocean; this phenomenon is called eddy saturation. The eddy saturation has been studied in both barotropic and baroclinic contexts in the presence of topography, yet many aspects of its dynamics remain elusive. We focus here on barotropic eddy saturation, which occurs in a narrow band of wind stresses where topographic-barotropic instability takes place. As a result, barotropic eddy saturation is highly sensitive to the specific geometry of bottom topography and to the boundary conditions. Here, we investigate whether the amplitude of the wind stress curl relative to that of a constant background wind stress can also modulate barotropic eddy saturation by modifying the global vorticity budget of a doubly periodic quasigeostrophic flow. We report that the zonal transport and the eddy saturation regime are sensitive to the wind stress curl and explore the underlying dynamics.
Strontium-Neodymium isotopic compositions of Higher Himalayan leucogranites and granitic gneisses from Sikkim Himalayas, India
Authors: Srivastava Tanya , Harris Nigel , Mottram Catherine , Wanjari Nishchal
Published: February 2023

The Himalayan leucogranites are important for deciphering the role of crustal thickening and anatexis during the tectono-thermal evolution of the Himalayas. The Higher Himalayan Sequences (HHS) in Sikkim are intruded by Miocene leucogranites which comprise two-mica-bearing (2mg) and tourmaline-bearing leucogranites (Tg) both of which are peraluminous in nature, and are characterized by high 87Sr/86Sr ratios and low 143Nd/144Nd ratios, typical of crustal values. In the case of 2mg, the average (87Sr/86Sr) ratio is 0.792020, and the average (143Nd/144Nd) ratio is 0.511764 whilst for Tg, the average (87Sr/86Sr) and (143Nd/144Nd) ratios are 0.772874 and 0.511912 respectively. In comparison to 2mg, Tg has lower average ratios of (87Sr/86Sr) and slightly elevated average ratios of (143Nd/144Nd). The Sr-Nd isotope compositions for the granitic gneisses from the HHS have an average (87Sr/86Sr) ratio of 0.764026 and an average (143Nd/144Nd) ratio of 0. 511959. The present day average εNd  values for 2mg, Tg, and granite gneiss are -17.1, -14.2, and -13.2 respectively. The granite gneiss samples all lie within the field defined by the HHS across the Himalayan orogen as do the Tg samples suggesting a source from pelitic rocks within the HHS. The 2mg samples are somewhat evolved towards more radiogenic Sr isotope ratios and slightly lower neodymium ratios suggesting either a source in metagreywacke rocks of the HHC or, alternatively, reflect minor melt contributions from anatexis of the Lesser Himalayan formations.Keywords: Sr-Nd isotopes, Source magma, Sikkim Himalayas, Leucogranites
Detection and characterization of earthquake accelerated landslides (EALs) using InSAR observations
Authors: Song Chuang , Yu Chen , Li Zhenhong , Utili Stefano , Frattini Paolo , Crosta Giovanni , Peng Jianbing
Published: February 2023

Earthquake-induced landslides often pose a great threat to the safety of human life and property, especially in seismic active regions. This has motivated plentiful studies with a focus on coseismic landslides that collapsed during or shortly after an earthquake. However, long-term seismic effects that activated unstable landslides but without causing failures/collapse even after a long period since the earthquake (months to years) are typically ignored due to the minor ground changes caused compared to collapsed slopes. These landslides respond to seismic stress disturbances differently from failed coseismic/post-seismic landslides and their movements are typically accelerated with increased sliding velocity after earthquakes. The acceleration phenomenon of these earthquake accelerated landslides (EALs) could be maintained for a long time and they may generate continuous damage to the ground and develop into catastrophic failures in the future. As a new type of landslides associated with earthquakes, EALs have been largely neglected by the emerging research. In our study, we used satellite radar (Sentinel-1) observations from October 2014 to August 2020 to detect and investigate EALs in Central Italy. Distinguished from previous studies based on single or discrete landslides, we established a large EAL inventory and statistically quantified as a whole their spatial clustering features against a set of landslide conditioning factors. Results show that EALs did not rely on strong seismic shaking or hanging wall effects to occur and larger landslides were more likely to accelerate after earthquakes than smaller ones. We also discovered their accelerating-to-recovering sliding dynamics, and how they differed from the collapsed coseismic landslides. These investigations serve as an important supplement to the complete picture of the landslide inducing mechanism by earthquakes and contribute to a more comprehensive long-term assessment of landslide risk.
A comparative study of soil water retention curves by the evaporation test with other experiments for Korean residual soil
Authors: Oh Seboong , Park Gyusoon , Seo Yongwon
Published: February 2023

The soil water retention curves(SWRCs) were acquired by experiments based on the evaporation method and compared with the result of volumetric pressure plate and chilled mirror tests for five samples in Korean residual soils. Under 100kPa suction, the SWRCs by the evaporation test agreed with those of volumetric pressure plate tests in the axis of effective saturation for five samples. In two samples, initial values of water content have shown 6% of difference, which doesn’t affect the fit of SWRCs. In the higher suction, the SWRCs were measured rapidly by chilled mirror tests. The SWRCs were fit efficiently  from low to high suction by both the evaporation and the chilled mirror tests. It is found that the fit only by low suction data couldn’t the actual SWRC accurately. Using the result of the current SWRCs and other data, the DB has been constructed and the parameters of the van Genuchten fit were interpreted. It was found that Korean residual soils are classified by three soils based on the range of void ratios.Acknowledgements This research is supported by grant from Korean NRF (2019003604), which are greatly appreciated.
Detecting permafrost freeze-thaw front propagation using time-laps ERT observations in a large column experiment
Authors: de Bruin Jelte , Bense Victor , van der Ploeg Martine
Published: February 2023

Cold regions are increasingly subjected to higher air temperatures, causing warming of permafrost and a deepening of the active layer. This activates hydrogeological groundwater flow and new groundwater pathways to emerge. Monitoring of the active layer depth occurs mainly with the use of temperature observations, but a more flexible and non-invasive method to study transient subsurface processes is with the use of Electrical Resistivity Tomography (ERT) observations. Automated time-laps ERT arrays are used to monitor the frozen ground evolution during various seasons, observing resistivity variations during freezing and thawing. Similarly, the leaching of meltwater into the ground under freezing/thawing conditions can be observed. Not only geophysical changes such as fluctuations in water content and water table, but also temperature variations affect the electrical resistivity field. In order to track the development of permafrost active-layer freeze-thaw fronts using ERT observations, it is thus essential that the effect of temperature on the resistivity is clearly defined at realistic scales representing field conditions. Our aim is to determine fluid resistivity at various stages during freezing and thawing and validate current temperature–resistivity relations for partly frozen soils.This study used a soil column (0.4 m diameter, 1 m heigh) equipped with 96 stainless steel electrodes placed at 8 horizontal rings of 12 electrodes each at various heights around the circumference of the column alongside with temperature sensors. The column was fully insulated on the sides and top except for the bottom, creating a 1D heat transfer system. The soil column was filled with quartzite sand with a D50 of 350 (μm) and organic matter content of 5 (wgt %). The experimental setup was placed within a climate chamber where the column was frozen to -4 °C and thawed to 3 °C over a 3-month period. During the freezing and thawing phase, a full 3D resistivity image was collected using the ERT at a weekly interval. Initial results show that the setup is capable of simulating permafrost freezing and thawing dynamics and ongoing work focuses on the relation between the temperature and time lapse ERT resistivity observations.
Conodont biostratigraphically constrained eruptive duration of Emeishan Large Igneous Province and implication for the end-Capitanian warming
Authors: Zhou Yinsheng , Yang Jianghai , Yuan Dongxun , Liu Ao , Cheng Liang
Published: February 2023

The emplacement and subsequent weathering of Emeishan large igneous province (LIP) have been linked to the climate change at the Guadalupian-Lopingian transition. Though lots of magneto-stratigraphic analysis and radio-isotopic dating works were conducted on the Emeishan LIP, the temporal correlation between Emeishan LIP and climate change is still in debate for the climatic records generally being archived in biostratigraphically dated marine successions. We here logged a Guadalupian-Lopingian limestone dominated succession in the Youjiang Basin located to the southeast of Emeishan LIP. A high-resolution conodont biostratigraphy was obtained for succession and constrained the studied succession in the conodont biozones of J. xuanhanensis, J. granti, and C. dukouensis. There developed multiple tuff and tuffaceous layers in this succession with stratigraphically lower ones geochemically akin to the high-Ti basalt and higher ones akin to the rhyolites of the Emeishan LIP. Analyzed zircons give average U-Pb ages at around 260 Ma and have chemical compositions like those recovered from Emeishan LIP. In coming the paleogeographic location, our petrological, geochemical, Nd-Sr isotopic and zircon U-Pb age and trace element data indicate the identified tuff materials were derived from the volcanic eruption of the Emeishan LIP. According to the established conodont biostratigraphy, the high-Ti basalt volcanism can be constrained in the conodont biozones of J. granti. Based on this biostratigraphically constrained eruption duration of Emeishan LIP, high-Ti basalt eruption can be confidently corrected with the conodont oxygen isotope indicated end-Guadalupian climate warming. Comparing with the rhyolitic tuff rocks, basaltic tuff layers contain a large population of older zircons which might indicate the addition of crustal materials into the basaltic magma enroute to the surface. There might be voluminous CO2 degassing from the crustal rocks including the carbonates and organic rich mudstones. This degassing in combination with the magmatic CO2 release and oxidation of buried organic materials in the coastal regions during the regression at that time could increase the atmospheric pCO2 and resulted in the climate warming.
Estimation of erosion rate parameters from neural network inverse modeling of river profile and thermo-geochronology data
Authors: Bernard Thomas , Glotzbach Christoph , Peifer Daniel , Neely Al , Ehlers Todd
Published: February 2023

The Earth's surface topography reflects the long-term competition between tectonic and climate-driven surface processes. River erosion is a fundamental process that sets the base level for hillslope processes and drives landscape evolution. River profiles reflect external processes, such as tectonic uplift and climate, as well as intrinsic properties of the landscape, such as lithologic variations. River profiles respond to perturbations in these parameters through local changes in channel gradient, which are transmitted upstream of the river channel. River networks affected by these processes may eventually suffer drastic river captures and important drainage reorganization. As a result, river profiles can be used to extract the uplift histories of landscapes. Geochemical data with sensitivities to different time scales, such as thermochronological ages and cosmogenic nuclide concentrations, can be combined in numerical models with river profile analyses to identify governing relationships response for a landscape history. However, the estimation of a complete denudation record through time remains challenging, especially in landscapes where river capture and drainage reorganization have strongly perturbated the river system.            In this study, we perform inverse modeling of river profiles and thermo- and geochronology data (i.e., low-temperature thermochronology and cosmogenic nuclides) to infer erosive parameters and the topographic history of different settings. The numerical model allows the prediction of river profiles, thermochronological ages (e.g., zircon fission tracks, apatite fission tracks and apatite helium ages), cosmogenic nuclide concentrations, and simplistic river captures. Variability in both rock uplift history and erodibility of different lithologies are accounted for. The model algorithm utilizes an efficient inverse modeling scheme "Simulation-Based Inference" to resolve unknown parameters such as uplift or erodibility of the different lithology. Results are presented from the Neckar catchment located in southwest Germany, which shows evidence for major river captures and drainage reorganization over the last ~10 Ma. Model results allow to reproduce the river profile and thermo-geochronological data of the Neckar catchment for specific uplift and erodibility. Moreover, early experiments indicate a better prediction of the observed data, and therefore, the parameters controlling the erosion rate, when considering river captures.
Satellite-based soil moisture could enhance the reliability of agro-hydrological modeling in large transboundary river basins
Authors: Eini Mohammad Reza , Massari Christian , Piniewski Mikołaj
Published: February 2023

Satellite-based observations of soil moisture, leaf area index, precipitation, and evapotranspiration facilitate agro-hydrological modeling thanks to the spatially distributed information. In this study, the Climate Change Initiative Soil Moisture dataset (CCI SM, a product of the European Space Agency (ESA)) adjusted based on Soil Water Index (SWI) was used as an additional (in relation to discharge) observed dataset in agro-hydrological modeling over a large-scale transboundary river basin (Odra River Basin) in the Baltic Sea region. This basin is located in Central Europe within Poland, Czech Republic, and Germany and drains into the Baltic Sea. The Soil and Water Assessment Tool+ (SWAT+) model was selected for agro-hydrological modeling, and measured data from 26 river discharge stations and soil moisture from CCI SM (for topsoil and entire soil profile) over 1476 sub-basins were used in model calibration for the period 1997-2019. Kling–Gupta efficiency (KGE) and SPAtial EFficiency (SPAEF) indices were chosen as objective functions for runoff and soil moisture calibration, respectively. Two calibration strategies were compared: one involving only river discharge data (single-objective - SO), and the second one involving river discharge and satellite-based soil moisture (multi-objective – MO). In the SO approach, the average KGE for discharge was above 0.60, whereas in the MO approach, it increased to 0.67.The SPAEF values showed that SWAT+ has acceptable accuracy in soil moisture simulations. Moreover, crop yield assessments showed that MO calibration also increases the crop yield simulation accuracy. The results show that in this transboundary river basin, adding satellite-based soil moisture into the calibration process could improve the accuracy and consistency of agro-hydrological modeling.
Downscaling the ESA CCI Soil Moisture: a new European dataset at 1 km for the period 2008-202
Authors: Zappa Luca , Schlaffer Stefan , Dorigo Wouter
Published: February 2023

The European Space Agency (ESA) Climate Change Initiative (CCI) provides long-term surface soil moisture (SM) records with daily temporal resolution. However, the coarse spatial resolution of approximately 25 km limits their use in many hydrological applications, such as agricultural water management, drought monitoring, and rainfall-runoff response.  To address this constraint, we downscaled the CCI SM product to 0.01° (~ 1 km) using machine learning and a set of static and dynamic variables affecting the spatial organization of SM. In particular, datasets describing the vegetation status throughout time, as well as land cover class and soil and topographic attributes were fed into a Random Forest model. Here, we will first present in detail the methodological framework that allowed us to generate the high-resolution dataset. Then, we will thouroughly evaluate its accuracy against in-situ measurements from across Europe, and further compare it to other SM products (e.g., from Sentinel-1). Finally, we will highlight the strengths and limitations of the downscaled SM dataset and discuss possible improvements.
Post-collisional Geological Structures off Gongliao District in Northern Taiwan
Authors: Lin Yi-Wen , Hsu Shu-Kun , Tsai Ching-Hui , Cho Yen-Yu , Lin Lien-Kai
Published: February 2023

The offshore area of northern Taiwan is subject to post-collisional collapse and under an extensional regime. Because of the change from a compressional environment to an extensional environment, a series of normal fault structures has occurred. The reverse faults in the Gongliao area of Taiwan, include the Longdong Fault, Wentzukeng Fault, Aodi Fault, and Fangjiao Faul, are distributed from inland to the coastline. However, their prolongations to the offshore area are unknown. In order to understand the possible fault extension to the offshore area and the possible fault activity, we conducted Sparker reflection seismic surveys in the offshore area of Gongliao. The Sparker seismic system is suitable for shallow water surveys and can provide high-resolution shallow structures. To understand the geological structures in our study area, sequence stratigraphy, seismic facies and faults identification are used to analyze our seismic profiles. According to the sequence stratigraphy, the transgressive surface, the last glacial maximum (LGM) unconformity, and last maximum flooding surface can be identified. In addition, the sand wave base surface, syn-rift unconformity and the acoustic basement are defined. We have identified 5 normal faults (i.e. Fa, Fb, Fc, Fd and Fe) in the prolongation of the onshore faults. All the identified faults cut through the basement and caused large offsets, forming half-graben basins. For the activity of these faults, the strata in the half-graben basin A formed by Fault a, is tilted, which was probably caused by the continuous growth of the fault. The strata in the half-graben basin B formed by Faults b and c, are inclined below the LGM unconformity, but the strata above the LGM unconformity are relatively flat. In contrast, only the sediments in the upper part of the half-graben basin B show the characteristics of sequence stratigraphy, which means the sediments deposit controlled by sea level change. In summary, we infer that the faults b and c were active before the LGM and relatively stable recently. Faults d and are covered by thick sediment layers, indicating early structures not active at all.
The microstructure of heavy rainfall in the Netherlands
Authors: Schleiss Marc
Published: February 2023

Raindrop size distributions (DSDs) are the main tool for describing and discussing rain microphysics. They play a crucial role in remote sensing of precipitation and extensive efforts have been devoted to measuring and modeling them. However, when it comes to DSDs in extreme rain, very few, reliable, results are available. Using numerical simulations, Srivastava (1978, 1982) and List (1988) theorized that for high enough rainfall intensities (>40 mm/h), DSDs should converge toward a stationary state where drop coalescence and breakup are in dynamical equilibrium with each other. In such conditions, the shape of the DSDs should be constant and the particle number concentration should be proportional to the rain rate. However, reliable evidence of such transitions toward a “number-controlled” remains scarce and many researchers have contested its existence.In this study, high-quality DSD observations from a network of 7 optical disdrometers belonging to the Ruisdael observatory for Dutch atmospheric science are used to take a new, fresh look at the issue. The main research questions are:Is there empirical evidence for a transition from size to number-controlled regimes at high rainfall intensities in the Netherlands?
What parametric model best fits DSDs at high rainfall rates?
Can the super-CC scaling of sub-hourly rainfall extremes with temperature highlighted by Lenderink et al. (2008) be explained by changes in DSDs?
To address the questions above, we analyze characteristic drop sizes (Dm, D0), number concentrations (NT, Nw) and state variables (LWC, Z, Zdr) for different classes of rainfall intensities and temperatures and study the shape of DSDs by comparing the goodness of fit of various parametric DSD models. We look at non-parametric descriptors such as the relative number of small versus large drops and study the scaling laws linking different moments of the DSD in heavy rain using single and double-normalization frameworks to assess possible convergence toward number-controlled regime at higher intensities.
Numerical experiences on using the RTM method in quasi-geoid modeling
Authors: Lin Miao , Li Xiaopeng , Yang Meng
Published: February 2023

In local and regional quasi-geoid modeling, the residual terrain modeling (RTM) method is often used to remove the short-wavelength gravity field signals from the measured gravity both on the ground and up in the air, in order to obtain the regularized and smooth gravity field which is suited for field interpolation and modeling. Accurate computation of RTM corrections requires a set of fine-tuned parameters in terms of the gravity forward modeling technique, digital elevation model (DEM), reference topography, and integration radius for the inner zone and outer zone. To our limited knowledge, this has not been systematically documented, albeit its importance is obvious. This work aims to clearly investigate the impact of these factors on the RTM correction computation and their effects on the quasi-geoid modeling so to provide practical guidelines for real applications. Two gravity forward modeling techniques, i.e., the prismatic approach and the tesseroidal approach, are employed to investigate the following issues existing in the practical use of the RTM method: ① can a combination of a high-resolution DEM and a DEM with a lower resolution replace the use of a single high-resolution DEM for the RTM correction computation without loss of accuracy? ② how to properly choose the integration radius for the inner zone and outer zone while costing less time and keeping the accuracy? ③ what are the performances of using the reference topographies obtained by the direct averaging, the moving averaging, and the spherical harmonic analysis and synthesis on the RTM correction computation and quasi-geoid determination? For obtaining objective findings, two research regions are selected for this investigation. One is the Colorado area (USA) having quite rugged terrains and the other is the Auvergne area (France) with moderate terrains. The numerical results show that, in the computation of RTM corrections to gravity anomaly and height anomaly, the combination of a dense DEM and a coarse DEM can replace the use of a single dense DEM without loss of accuracy. The increasing and decreasing of the integration radius for the inner zone and outer zone do not influence the RTM correction computation much. The recommended values are 10 km for the inner zone and 111 km for the outer zone. The use of different reference topographies changes RTM corrections, however, the final quasi-geoid models are at the similar accuracy level.