bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Madden Julian Oscillation and boreal summer intraseasonal oscillation on the marine heat waves of East-Asian Marginal Seas
Authors: Dasgupta Panini , Nam SungHyun , Jayanthi Sasikumar Saranya , Mathew Koll Roxy
Published: February 2023

Recent intensification of the west Pacific warmpool has altered the western boundary currents and subtropical gyres, and turned East-Asian marginal seas (EAMS) into the most rapid warming ocean bodies on Earth. Along with the long-term increasing temperature, the EAMS often experience episodic events of incredibly high sea surface temperatures (SST), known as marine heatwaves (MHWs), which significantly adversely affect the vibrant marine ecosystems in these regions. Interannual climate forcing, such as the decaying El Niño Southern Oscillation (ENSO), also creates favourable conditions for MHWs in EAMS. However, in addition to the long-term trend and interannual background conditions, dominant intraseasonal variability in the tropics, such as Madden Julian Oscillation (MJO) in boreal winter and Boreal Summer Intraseasonal Oscillation (BSISO) in boreal summer, may influence the EAMS SST remotely. This study explores the pathways and mechanisms by which MJO and BSISO influence MHWs in the EAMS region. We show that specific phases of MJO (phases 2, 3, and 4) during boreal winter and summer (BSISO phases 5, 6, and 7) create favourable conditions for the occurrence of MHWs in these regions. Using Estimating the Circulation and Climate of the Ocean (ECCOv4) reanalysis datasets, we further separate the relative contribution of heat and salt changes by MJO and BSISO to the MHWs in EAMS, suggesting key factors that are vital in triggering MHWs in different areas of EAMS.
Neoproterozoic-Paleozoic Convergent Margins in Northeast Queensland, Australia - New Ideas from the Discovery of Metamorphic Diamonds and Ophiolites.
Authors: Edgar Alexander , Sanislav Ioan , Dirks Paul , Spandler Carl
Published: February 2023

The Tasmanides of eastern Australia record a complex geological history. The central, and southern Tasmanides have been widely interpreted to reflect long-lived, accretionary-style convergent tectonics. The northernmost Tasmanides, which extend into north Queensland, are more poorly understood, but considered highly prospective for numerous styles of mineralization. The region contains several slices of mafic-ultramafic rocks, situated along major regional structures. The mafic-ultramafic complexes record strong, oceanic geochemical signatures, and are structurally interleaved within high grade, strongly deformed, Paleozoic basement metamorphic assemblages. Along the Clarke River Fault, the Running River Metamorphics, which host ophiolitic mafic-ultramafic rocks, also record evidence of diamond facies, ultra-high pressure (UHP) metamorphism. The discovery of diamond facies metamorphism, in conjunction with convergent margin ophiolites, suggests that the Clarke River Fault may represent a continental suture zone. This is the first indication of continent suturing in the Tasmanides, and challenges the idea that the Tasmanides, and greater Terra Australis Orogen, represent a simple accretionary system.
A novel coastal wave model with improved nonhydrostatic equations
Authors: Wang Hang , Wang Gang , Liang Qiuhua
Published: February 2023

Waves are one of the essential factors triggering disastrous hazards in coastal and estuary areas. Simulation and understanding of their propagation process from deep water to nearshore are important for management and protection of coastal regions. Development of nonhydrostatic models has received increased attention in recent years and depth-integrated nonhydrostatic models have been widely used in large-scale applications. However, most existing depth-integrated nonhydrostatic models neglect the vertical advection and dissipation terms in the vertical momentum equation and assume linear distribution of pressure and flow velocities. These simplified equations are therefore not able to depict the physical details of certain wave dynamics,  prohibiting the application in wave prediction in relative deep water.This paper adopts the quadratic polynomials to describe both the pressure and velocity terms to improve the linearity and nonlinearity accuracy of the formulation. As the derived nonhydrostatic wave equations involve only the first- and second-order spatial derivatives and are formulated at a similar frame to the previous depth-integrated models, they can be numerically solved using the standard numerical schemes adopted in the previous models. Specifically, a fractional step method is adopted to divide the numerical solution procedure into the hydrostatic and nonhydrostatic steps. A second-order MUSCL-Hancock Godunov-type scheme is employed in the hydrostatic step to obtain the temporary solution; then a finite difference method is used in the nonhydrostatic step to calculate the hydrodynamic pressure by solving the Poisson's equation to achieve the final numerical solution over a full time step. The proposed model is validated against a series of experiment tests. Higher solution accuracy is confirmed by comparing the simulation results with those produced by existing depth-integrated nonhydrostatic models.Keywords: Nonhydrostatic Model; Coastal Hazards; Finite-Volume Method; Finite-Difference Method; Wave Propagation
Source-to-Sink Canyon-Fan Interaction in a Closed Basin
Authors: Zhang Li , Parker Gary
Published: February 2023

Closed basins are commonly found in desert environments. They delineate an excellent configuration with which to study source-to-sink processes. Here we use the Rainbow Canyon-Panamint Valley canyon-fan system, Death Valley, USA as an example for the development of a general numerical model. The upstream region of our study reach is incising into bedrock, with a retreating knickpoint. The downstream region of our study is alluviated, and ends with a closed boundary. In between is a normal fault. The upstream reach is in relative uplift, driving incision (e.g. Argus Range), and the downstream reach is in relative subsidence, driving deposition on an alluvial fan (e.g. Panamint Valley). The closure of the basin at the downstream end provides a simple model of a mountain range on the opposite side of the valley (Panamint Range). We use the model of Zhang et al. (2020) to study a range of conditions. At one end we study the conditions for the formation of a hanging valley, with a vertical waterfall at the fault. At another end we study the conditions for the partial or complete alluviation of the canyon reach. We place emphasis on conditions where the canyon and fan “talk” to each other, versus conditions where the fan becomes a passive recipient of sediment from the canyon. We also show the consequences of opening up the downstream end of the basin, so that sediment is removed at the base of the fan (e.g. Armagosa River). We offer a versatile tool to study source-to-sink morphodynamics in an arid environment.
Evolution of the African Mantle Domain and its enriched signal: perspective from pre-200 Ma ophiolites
Authors: Azevedo Berquo de Sampaio Piero , Li Zheng-Xiang , Doucet Luc Serge , Gamaleldien Hamed
Published: February 2023

Earth’s mantle is highly heterogeneous, with mantle-derived rocks sampling depleted and enriched domains both in intraplate settings and along spreading ridges. The most notorious isotopic anomaly is the DUPAL anomaly, where an overall strong recycled isotopic signature occurs. Studies on Tethyan and Paleo-Tethyan ophiolites have shown the persistence of “DUPAL signature” in those oceans, which paleogeographic reconstructions place on approximately the same position as the present-day Indian Ocean and thus argue for a long-lived “DUPAL signature” in the mantle. The origin of the DUPAL anomaly is controversial, with many studies pointing to it being a primordial feature. More recently, however, it has been shown that plume products in the African Mantle Domain (AMD), of which the DUPAL anomaly region is a part of, generally bear a more enriched signal than plume-related rocks in the Pacific Mantle Domain. This observation has been hypothesized to be related to the formation of the Pangea supercontinent above the present-day AMD, and therefore offering a geodynamic scenario capable of explaining the origin of the enriched isotopic signature of the AMD. However, present-day ocean crust record is limited in time, extending to 200 Ma at maximum, younger than the formation of Pangea at ca. 320 Ma. To investigate the oceanic record of mantle enrichment further back in time and test the influence of supercontinent cycle on the composition of the AMD, it is necessary to utilise preserved oceanic terranes in orogenic belts. In this study we compiled isotopic data from preserved oceanic terranes related both to the formation of the AMD, starting from the assembly of Gondwana till the duration of Pangea, including that of the Mozambique, Adamastor, Goias-Pharusian, Iapetus, Rheic, Qilian-Shangdan, Paleo-Tethys, Meso-Tethys and Neo-Tethys paleo-oceans. Neodymium isotopic data is the most widely available for these ophiolites. The Nd isotopic data indicates a progressively more depleted signal before Gondwana formation until it reaches a maximum and stays relatively stable until shortly after Pangea break-up, where noticeable decrease in depletion occurs. Lead isotopic data is less readily available, existing data nevertheless allow to observe an increase in Th/U ratio during Gondwana formation. Taken together, these observations indicate an increase in recycled continental components in the mantle source of the AMD ophiolites. We envisage this to be evidence for mantle enrichment during the formation of Gondwana and Pangea within the AMD. New isotopic analyses are still needed to paint a clearer picture of the interplay between the supercontinent cycle and mantle geochemistry.
The formation and evolution of northeastern ends of the ECSSB, South Sea of Korea, and its significance for petroleum exploration
Authors: Roh Eul , Jang Yirang , Woo Areum , Kwon Sanghoon
Published: February 2023

 The South Sea of Korea has three offshore concession blocks, including a Joint Development Zone(JDZ) that is set up by the license agreement between Korea and Japan. The geological research of the offshore South Sea of Korea is insufficient to define the evolution history and its significance for petroleum accumulation. In this study, evolution of the Xihu Sag within the JDZ area at the South Sea of Korea is tackled based on re-interpretation of the seismic and well data, and are correlated tectonically with that of the ECSSB(East China Sea Shelf Basin). The ECSSB has been initially developed as a back-arc basin over the over-riding Paleo-Pacific plate, and experienced complex tectonic history by successive subduction of the tectonic plates including the Paleo-Pacific (Izanagi) Plate, the Pacific plate, and the Philippine plate since Late Cretaceous in age. The results indicate that the study area can be subdivided into three tectonic domains: Western Slope Belt, Central Uplift Belt, and East Slope Belt. The structural similarity with those of the ECSSB, although the details of structural characteristics are different in different localities, under regional influence of successive subductions of the same tectonic plates, resulting in the conclusion that the area can be assigned into the northeastern ends of the Xihu Sag of the northeastern ECSSB. This might be a common feature of oil–gas accumulation in the eastern ECSSB, and highlights the potential for petroleum exploration at the study area, although further studies on the play concept and complex petroleum system of the area are required.
Stochastic properties and statistics of salt intrusion in estuaries in a warming climate
Authors: Lee Jiyong , Biemond Bouke , de Swart Huib , Dijkstra Henk
Published: February 2023

Salt intrusion is part of natural estuary dynamics, where saline water enters inland by tides and exchange flow, and is diluted by fresh river water. These processes and feedbacks are complicated and inherently stochastic; and it is not yet well understood how they determine the statistical behavior of the salt intrusion length. More importantly, there are large uncertainties regarding future changes of the forcing of the salt intrusion in a warming climate. In this presentation, we will introduce a new stochastic model that computes temporal changes of the salt balance equation with the decompositions of river discharge and salt intrusion length into deterministic and stochastic components. The developed framework is applied to field observations in the San Francisco Bay (USA) and shown to well reproduce general statistics of salt intrusion length. Next, the model is applied to estuaries in Europe under projected river discharge distributions up to 2100 using two large ensembles of the Community Earth System Model. The key assumption in the model is that the changes in the river discharge are the main driver that induces variability and changes in salt intrusion length in the coming decades. Our results show that there will be significant increase of salt intrusion during dry periods in many European estuaries, especially those at low latitudes. The analysis stresses that, for adequate water management, great attention is needed in monitoring and predicting salt intrusion lengths in the future.
Quantifying the riverine sources of sediment and associated radiocaesium deposited off the coast of Fukushima Prefecture
Authors: Chaboche Pierre-Alexis , Yoshifumi Wakiyama , Takata Hyoe , Wada Toshihiro , Evrard Olivier , Misonou Toshiharu , Shiribiki Takehiko , Funaki Hironori
Published: February 2023

The Fukushima-Daiichi Nuclear Power Plant (FDNPP) accident trigged by the Great East Japan Earthquake and subsequent tsunami in March 2011 released large quantities of radionuclides in terrestrial and marine environments of Fukushima Prefecture. Although radiocaesium (i.e. 134Cs and 137Cs) activity in these environments has decreased since the accident, the secondary inputs via the rivers draining and eroding the main terrestrial radioactive plume were shown to sustain high levels of 137Cs in riverine and coastal sediments, which are likely deposited off the coast of the Prefecture. Accordingly, identifying the sources of sediment is required to elucidate the links between terrestrial and marine radiocaesium dynamics and to anticipate the fate of persistent radionuclides in the environment.The objective of this study is to develop an original sediment source tracing technique to quantify the riverine sources of sediment and associated radionuclides accumulated in the Pacific Ocean. Target coastal sediment cores (n=6) with a length comprised between 20 and 60cm depth were collected during cruise campaigns between July and September 2022 at the Ota (n=2), Niida (n=1) and Ukedo (n=3) river mouths. Prior to gamma spectrometry measurements, sediment cores were opened and cut into 2 cm increments, oven-dried at 50°C for at least 48 hours, ground and passed through a 2-mm sieve.Preliminary results regarding the spatial and depth distribution of radiocaesium in these samples show a strong heterogeneity, with highest radiocaesium levels (up to 134 ± 2 and 4882 ± 11 Bq kg-1 for 134Cs and 137Cs, respectively) found in coastal sediment cores located at the Ukedo river mouth. On the opposite, no trace or low levels of Fukushima-derived radiocaesium were found in the Niida and in one sediment core of the Ota River mouths. Additional measurements will be conducted to determine the physico-chemical properties of this sediment, in order to select the optimal combination of tracers, which will then be introduced into un-mixing models. This increase knowledge will undoubtedly be useful for watershed and coastal management in the FDNPP post-accidental context.
Spatial and temporal explicit and dynamic zoning of crop water consumption under past and future climate and socioeconomic changes: a case study of China
Authors: Ji Xiangxiang , Zhuo La , Wu Pute
Published: February 2023

The impacts of multiple changes in climatic and socioeconomic conditions within countries and regions are spatially heterogeneous, thus complicating stringent agricultural water management. Here we developed a framework for the dynamic identification of zone types and provided targeted agricultural water management strategies for each zone in response to global change. Considering China as an example, eight zones of typical major grain crop production prefectures were identified based on an analysis of the spatial and temporal evolution characteristics at four levels (agricultural, natural, social, and economic) according to the water footprint of major grain crop production at the prefecture level for the past 15 years (2004-2018). We then presented the response of China's future zoning landscape for 2030, 2050, and 2080 under three representative scenarios by combining shared socioeconomic paths (SSPs) and representative concentration paths (RCPs). Results show that, by 2080, the national water consumption of the major grain crop production will increase under all scenarios. Half of prefectures facing function shifts are likely to change from low to high water consuming zones. Different zonal prefectures react differently under global changes, especially those that are prone to functional transformation, should pay attention to their instability. Consideration of the water footprint in agricultural zoning is of great importance for national sustainable water resources management. This study proposes a more explicit approach to coping with global change, that is, to propose locally appropriate agricultural water management strategies and measures for China and beyond.
Relationship of aerosol optical properties and particle types from SPARTAN and AERONET data in South Korea
Authors: Eom Sujin , Kim Jhoon , Lee Seoyoung , Cho Yeseul , Park Sang Seo
Published: February 2023

SPARTAN (Surface Particulate Matter Network) is a network of Particulate Matter (PM) samplers that analyze aerosol samples for PM mass concentration and chemical composition. Two aerosol samplers were installed at two sites in Korea: Yonsei University at Seoul and UNIST (Ulsan Institute of Science and Technology) at Ulsan. These SPARTAN filter samplers and additional nephelometers provide the PM2.5 mass concentration and reconstructed chemical speciation data (May, 2019~ Nov, 2021). In most SPARTAN PM2.5 cases, both sites showed time series patterns similar to data from the Korean regional observation network (Airkorea). In the case of high-loading fine dust, the daily value was relatively well matched with Airkorea data. The co-location of these SPARTAN samplers with AERONET (Aerosol Robotic Network) sun photometer presents the possibility of analyzing aerosol optical depth, aerosol surface mass concentration, and aerosol speciation data together. If the fraction of a particular component is high, the optical properties may vary. When the mass concentration of sulfate was relatively high, AERONET data displayed a large distribution of non-absorbing small particles. Similar to the previous analysis, we also show a detailed analysis of the relationship between other chemical components and optical properties.
A refined chronology and spatial distribution of artificial radionuclide fallout (239,240Pu, 137Cs) in South America
Authors: Chaboche Pierre-Alexis , Evrard Olivier , Foucher Anthony , Sabatier Pierre , Tassano Marcos
Published: February 2023

Sedimentary sequences have received a growing interest as a support for conducting climatic and environmental reconstructions covering the 20th century period, which has been highly impacted by socio-environmental changes. South-America is one of the regions of the world the most impacted by these changes (e.g. agricultural expansion, extreme climatic events) which induce many deleterious consequences (e.g. increase of soil erosion, transfer of contaminants). However, quantitative information regarding soil erosion and sediment accumulation processes at the catchment scale is currently lacking to determine the magnitude of these phenomena and promote effective policies to mitigate their environmental and economic impacts.Fallout of anthropogenic radionuclides (137Cs, 239Pu and 240Pu) emitted by atmospheric nuclear weapon tests conducted between 1945 and 1980 provides an opportunity to overcome this lack of information. Indeed, artificial radionuclides bound to fine-grained sediment have been increasingly recognized as powerful tools to conduct environmental, climatic and soil redistribution rate reconstructions during the Anthropocene. Although spatial and temporal reconstructions of this fallout have been conducted worldwide, this information remains scarce in South America. In addition, scientific controversies emerged regarding the contribution of French atmospheric nuclear tests to the deposition of artificial radionuclides in this region of the world, requiring further investigation.Based on a compilation of 137Cs inventories in undisturbed soil profiles (n=96) and a digital soil mapping approach, an open-access baseline map of 137Cs fallout at the subcontinental scale of South America was created. The results showed that the 137Cs inventory technique should be appropriate to reconstruct soil erosion in intensive agricultural landscapes of Chile, Argentina, Uruguay and southern Brazil and theoretically applicable in Paraguay, Bolivia and Peru. Compared to previous estimations, higher levels of 137Cs fallout were observed between 20 and 60° South latitude. Additional measurements were therefore conducted in undisturbed soils and lake sediment cores collected at these latitudes by analyzing the 240Pu/239Pu atomic ratios, which is a powerful tool to determine the sources and their respective contributions to the deposition of anthropogenic radionuclides. Significantly lower plutonium atom ratios were found and attributed to the higher contribution (up to 60% in Uruguay) of the fallout following French atmospheric nuclear tests between 1966 and 1974.This refined chronology and spatial distribution of bomb-derived fallout will undoubtedly be useful to avoid misinterpretations of sediment core dating and reconstruct soil redistribution rates during the Anthropocene in South America.
MultiResUNet, VGG16, and U-Net applications for landslide detection
Authors: Lee Saro , Rezaie Fatemeh , Panahi Mahdi
Published: February 2023

The frequent occurrence of disastrous landslides can lead to significant infrastructure damages, loss of life, and the relocation of populations. Early detection of landslides is crucial for mitigating the consequences. Today, deep learning algorithms, particularly fully convolutional networks (FCNs) and their variants such as the ResU-Net, have been utilized to rapidly and automatically detecting landslides. In the current study, a novel method using three new deep learning models: MultiResUNet, VGG16, and U-Net was used to detect landslides in Hokkaido Island, Japan. Our dataset is comprised of Sentinel-2 images and a mask layer, which includes "landslide" or "non-landslide" labels. The suggested framework was based on the analysis of satellite images of landslide-prone locations using bands 2 (blue), 3 (green), 4 (red), and 5 (visible and near-infrared) of Sentinel 2, slope and elevation factors. We trained each model on the dataset and evaluated their performance using a variety of statistical indexes, including precision, recall, and F1 score. The results showed that the MultiResUNet model outperformed the other two models, achieving an accuracy of 82.7%. The VGG16 and U-Net models achieved accuracies of 65.5% and 67.2%, respectively. The results indicated the capability of deep learning algorithms to process satellite images for early landslide detection and provide the opportunity of implementing efficient and effective disaster management strategies.
Circulation characteristics and formation mechanism of heavy rainfall in summer over the Southeastern Tibetan Plateau
Authors: Cao Dianbin , Chen Xuelong , Du Yu , Ma Yaoming , Hu Yang
Published: February 2023

The southeastern Tibetan Plateau (SETP) is the most predominant summer rainfall region in the Tibetan Plateau. However, the atmospheric circulation characteristics associated with regional heavy precipitation over the SETP are still unclear. Based on 35 years of daily precipitation observations in 1980-2014, the types of weather systems causing regional heavy precipitation events over the SETP are objectively classified into two representative patterns, named the Tibetan Plateau vortex type (TPVT) and mid-latitude trough type (MLTT), through hierarchical clustering technique. The classification results show a clear connection between the heavy precipitation and the positive vorticity anomaly, moisture convergence, and southeastward shift of the westerly jet core contributing to anomalous rising motion. It was found that TPVT and MLTT resulting in heavy precipitation events were derived from the eastward development of the Tibetan Plateau vortex related to dry-wet potential vorticity processes and the penetration of deep extratropical trough-ridge circulations, respectively.
Laccadive Ridge as a Continental Fragment: Pre-rift Geometry, Rifting style and Volcanism based on Multi-channel Seismic and Gravity Interpretation
Authors: George Gilbert M , Radhakrishna Munukutla , Pande Kanchan
Published: February 2023

Laccadive Ridge located off the southwest continental margin of India, is identified as part of highly extended continental crust that is heavily intruded by volcanics or as an aseismic ridge formed by the Reunion hotspot trace. Although there is a growing body of evidence suggesting it as a continental fragment, there has not been a clear identification of rift related structures at the margin. In this study, we use multichannel seismic and gravity data to decipher the nature of the Laccadive Ridge. The multichannel seismic reflection data reveal fault structures in the Laccadive Basin which separates the Laccadive Ridge from the western continental margin of India indicating that the basin is underlain by extended continental crust. Two rifting directions are evident from the seismic data that are aligned with the Precambrian NW-SE to NNW-SSE Dharwar trend and the ENE-WSE Satpura trend of the Indian shield. These trends are conformable with the trends in the gravity anomaly map which matches very well with the identified graben structures on the Ridge. We suggest that the magma travelled through the faults in the highly extended crust and gave rise to the numerous intrusions which are present all along the ridge. To restore the pre- India Madagascar geometry of the Laccadive Ridge, the gravity anomalies have been inverted to estimate the depth to Moho beneath the ridge. The volcanic addition to the crust due to magmatism and possible underplating was calculated using the adiabatic decompression melt generation models, and used to estimate the final crustal thickness. Stretching factors were calculated from these crustal thickness values and used to understand the pre-rift extent of the continental fragment. The results altogether give important information about the rift-related structures along the ridge and insights into the importance of this continental fragment in the evolution of India and Madagascar. 
Detection and attribution of extreme precipitation events over the Asian monsoon region
Authors: Dong Tianyun , Dong Wenjie , Zhu Xian
Published: February 2023

Extreme precipitation events have enormous impacts on the natural and human aspects of most regions. This study presents a detection and attribution analysis of extreme precipitation in the Asian monsoon region (AM) from 1950 to 2014 using the Coupled Model Intercomparison Project Phase 6 (CMIP6) models. The observed positive PI (probability-based index) trends for annual maxima of 5-day (Rx5day) and 1-day (Rx1day) precipitation accumulations are 6.04%/100yr and 10.96%/100yr. The simulated PI trends for Rx5day and Rx1day under greenhouse-gas (GHG) forcing are 9.70% /100yr and 10.86% /100yr, respectively, while the trends are −8.99% /100yr and −7.01%/100yr under the aerosol (AER) forcing. Greenhouse-gas concentrations alone cause extreme precipitation increases, while the offsetting effects of anthropogenic aerosols may result in weaker increasing trends in ALL forcing simulations. The anthropogenic (ANT) signals are detectable, while the natural (NAT) signals could not be distinguished from the noise (internal climate variability) based on the optimal fingerprinting method. GHG forcing is detected for AM’s extreme precipitation when GHG, AER, and NAT forcing are all considered. A three-signal analysis confirms that CO2 forcing had a detectable influence on observations, whereas the influence of volcanic and solar-irradiance forcings could not be distinguished. Our results provide evidence that anthropogenic greenhouse gases (mainly CO2) are the prime external factors influencing the increase of AM’s extreme precipitation.
An evaluation of global atmospheric CO2 simulation by the GEOS-Chem using multiple observations in the period 2010-202
Authors: Kang Yeri , Song Chang-Keun
Published: February 2023

Atmospheric carbon dioxide (CO2) in the atmosphere has increased mainly due to anthropogenic fossil fuel emissions, resulting in accelerating global warming and increasing climate variability. Atmospheric chemical transport models are powerful tools for understanding mechanisms between emission/sink and the spatiotemporal distribution of atmospheric CO2.We aim to provide information on GEOS-Chem CO2 simulation to assess the mitigation strategies over East Asia under future emission scenarios. To achieve this, we first need to evaluate the model performance of the global simulation. We investigated trends and characteristics of atmospheric CO2 from the model with ground-based in-situ observations from the World Data Centre for Greenhouse Gases; (WDCGG), Total Carbon Column Observing Network (TCCON), and satellite observations (e.g., the Greenhouse Gases Observing Satellite; GOSAT, the Orbiting Carbon Observatory 2; OCO-2).Overall, modeled CO2 concentrations showed reasonable seasonal, annual amplitudes, and spatiotemporal distributions. They also agreed well with ground-based observations and satellite observations. Our global simulation was highly correlated with in-situ observations (Index of agreement (IOA) ≈ 0.9), and also showed excellent performance (Correlation coefficient (R) > 0.9) compared with satellite observations. Our study provides broad information on global simulation to identify features of monitoring measurements and modeling. We anticipate that our model configuration is capable of studying future emission scenarios in East Asia.
Heavy Water Isotope Precipitation in Inland East Antarctica Accompanied by Strong Southern Westerly Winds during the Last Glacial Maximum
Authors: Kino Kanon , Cauquoin Alexandre , Okazaki Atsushi , Oki Taikan , Yoshimura Kei
Published: February 2023

Stable water isotope signals in inland Antarctic ice cores have provided wealth of information about past climates. This study investigated atmospheric circulation processes that influence precipitation isotopes in inland Antarctica associated with atmospheric circulations in the southern mid-latitudes during the Last Glacial Maximum (LGM, ~21 000 year ago). A couple of probable climates during this climate period were simulated using the isotope-enabled atmospheric general circulation model MIROC5-iso. Our results showed a steepened meridional sea surface temperature gradient in the southern mid-latitudes associated with a strengthening of the southern westerlies. This change in the atmospheric circulation enhanced the intrusion of warm and humid air from low latitudes that contributes to precipitation events, inducing heavy water isotope precipitation inland East Antarctica. Our results suggest that past southern westerlies can be constrained using water isotopic signals in Antarctic ice cores.
Nitrogen accumulation in a big lake along wetland evolution affected by groundwater and surface water interaction in central Yangtze River Basin
Authors: Tang Liansong
Published: February 2023

Nitrogen pollution is an important cause of lake eutrophication, and the deterioration of lake water quality caused by nitrogen pollution has attracted wide attention worldwide. Honghu Lake is a large lake located in the middle and lower reaches of the Yangtze River in China, which has been threatened by nitrogen pollution for a long time. We studied the evolution of Hong Lake from 1990 to 2020. From 1990 to 2005, the natural water area of Hong Lake decreased by 72%, and most of the natural water was converted into aquaculture water, resulting in the rapid deterioration of lake water quality. Farming was gradually banned after 2005 and the area of natural water has been restored, but the lake's water quality has not improved, indicating that the lake is also threatened by other sources of pollution. According to the results of two groundwater surveys in 2011-2012 and 2019-2020, we found that the nitrate nitrogen content in groundwater in the study area increased from 1.29mg/L to 3.58mg/L. We also collected sediment samples from the lakeshore zone, and the test results showed that a large amount of exchangeable nitrogen was adsorbed on the sediment. Groundwater is one of the important factors causing nitrogen pollution in lake.
Effects of roof greening and surface heating on street-canyon flows
Authors: Rho Ju-Hwan , Mun Da-Som , Wang Jang-Woon , Kim Jae-Jin
Published: February 2023

Extreme high-temperature phenomena in urban areas are recognized as natural disasters. Asphalt roads and high-rise buildings are concentrated in megacities, and buildings and roads may contribute to extremely high air temperatures, especially in the summer season. For the improvement of the thermal environment in urban areas, green spaces are being created on building roofs. In this study, we investigated the effects of roof greening on street-canyon flows in the presence of roof and ground heating using a computational fluid dynamics (CFD) model. For validation, we compared the simulated street-canyon flows to the measured ones in a wind tunnel experiment. The CFD model used in this study reproduced the wind speeds, turbulent kinetic energies, and air temperatures in a street canyon in the presence of building roof and ground heating.
Daily Streamflow Forecasting in the Mahanadi River Basin using a Novel Deep Learning-based Model
Authors: Khatun Amina , Chatterjee Chandranath , Sahoo Bhabagrahi
Published: February 2023

Flood is one of the most devastating natural disasters accounting for the loss of life and property of millions of people every year. Since 2000s, floods have become more frequent in some parts of the world, especially in the tropical region. In India, many frequent extreme floods are found to occur recently. While the structural measures of flood management are not always feasible, the non-structural measures, such as flood forecasting plays a vital role in developing early flood warning systems. In the present study, a novel deep learning model, namely Smoothing-based Long Short-Term Memory (Smooth-LSTM) model is developed for daily streamflow forecasting at the head of the delta region in the Mahanadi River basin, eastern India. This modelling framework integrates smoothing filters and the traditional LSTM networks to predict the daily streamflow foreacasts up to 5-days lead-time. This model follows a sequence-to-single output approach, with the time-lagged streamflows as the only input variable. The Smooth-LSTM model is able to predict the streamflows reasonably well with a Nash-Sutcliffe Efficiency of 0.87–0.82 up to a lead-time of 5-days. The overall model performance is found to be satisfactory with the ability to capture the observed streamflows within the 90% uncertainty bands.
In-situ C and Mg isotopes of dolomite from the giant Bayan Obo REE deposit: Implications for recrystallization and recycled carbonate in the source
Authors: Chen Wei , Yang Fan , Lu Jue
Published: February 2023

Carbonatites are known to host over 95% of light rare earth element (REE) resource, and the REEs are commonly hosted in minerals with well-established extraction methods. Most REE mineralized carbonatites are associated with hydrothermal alteration/recrystallization. Identifying the source composition and role of recrystallization is crucial for understanding the formation of the giant carbonatite-associated REE deposit. Here we report the first in-situ carbon and magnesium isotopic compositions for the hosting dolomite in the Bayan Obo deposit.In-situ carbon isotope analyses of dolomite from the coarse-grained (CM), fine-grained (FM) and heterogeneous-grained (HM) samples show a wide range of δ13C values (-5.19‰ to 2.08‰), which is distinct from the common mantle-derived carbonatite and slightly overlaps the range of sedimentary carbonate. CM dolomite displays almost homogeneous carbon isotope compositions (δ13C=-1.29‰ to 0.16‰) with the average δ13C of -0.82‰. Recrystallized dolomites from both FM and HM samples vary greatly, and FM dolomite generally displays a heavier δ13C range (-3.94‰ to 2.08‰) compared to that for HM dolomite (-5.19‰ to 0.64‰). CM dolomite also shows relative consistent Mg isotope compositions in the range of -0.27‰ to 0.05‰ with an average of -0.10‰, which is similar to the mantle value. δ26Mg values of FM and HM dolomites vary greatly from -1.18‰ to 0.06% with averages of -0.40‰ and -0.32‰, which are lighter compared to that of CM dolomite. The recrystallized dolomites (FM and HM) are characterized by depleted light REE (LREE) and increased Pb/CeN features compared to the pristine dolomite (CM). Moreover, the LREE depletion and Pb/CeN increase correlate with the lighter Mg isotope compositions. The highly variable C isotopes recorded by FM and HM dolomites (lighter or heavier compared to the pristine dolomite) involve both recrystallization and degassing. The combined in-situ Mg and C isotope compositions of the pristine dolomite suggest the Bayan Obo carbonatite sourced from the mantle previously fertilized by fluids derived from the carbonate-bearing subduction slab.
The application of the SBAS-PSInSAR method in monitoring surface deformation in Choushui River Fluvial Plain, Taiwan
Authors: Nguyen Thai Vinh Truong , Ni Chuen Fa , Nugraha Gumilar Utamas
Published: February 2023

Natural processes like tectonic activities and soil consolidation can induce land subsidence, as can human activities such as groundwater or oil extraction, mining, and construction. Among the issues stated, groundwater extraction substantially contributes to global subsidence. In the long term, land subsidence can cause unanticipated building and infrastructure damage, resulting in significant financial consequences for governments. Therefore, it is critical to monitor subsidence regularly to inform policy decisions and control the factors contributing to land subsidence.The research area for this study is the Choushui River Fluvial Plain (CRFP), located in Taiwan's central region. The CRFP is a major agricultural zone and includes a Taiwan High-speed Rail system (THSR) segment. Monitoring and analyzing land subsidence patterns in the CRFP is critical for local governments to reduce the impact of subsidence on civilian life and public transportation.This study utilized the SBAS-PSInSAR technique to process multiple Sentinel-1’s SAR images and assess the surface deformation in the CRFP. The results indicated three sinking locations in the northern half that could not be previously recorded by point-wise measurement interpolation, indicating the possibility of identifying local deformation of this InSAR-based method. Furthermore, it also detected a massive subsidence funnel with a sinking rate of up to -60 mm/year in the vicinity of the THSR railway in the south, which might potentially threaten railway safety. Last but not least, the obtained results demonstrated the compatibility of the SBAS-PSInSAR and conventional geodetic approaches in monitoring large-scale surface deformation. 
DOCU-CLIM: A global documentary climate dataset for climate reconstructions
Authors: Bronnimann Stefan , Burgdorf Angela-Maria
Published: February 2023

Documentary climate data describe evidence of past climate arising from predominantly written historical documents such as diaries, chronicles, newspapers, or logbooks. Over the past decades, historians and climatologists have generated numerous document-based time series of local and regional climate. However, a global dataset of documentary climate time series has never been compiled, and documentary data are rarely used in large-scale climate reconstructions. Here, we present the first global multi-variable collection of documentary climate records. The dataset DOCU-CLIM comprises 621 time series (both published and hitherto unpublished) providing information on historical variations in temperature, precipitation, and wind regime. The series are evaluated by formulating proxy forward models (i.e., predicting the documentary observations from climate fields) in an overlapping period. Results show strong correlations particularly for the temperature sensitive series. Correlations are somewhat lower for precipitation sensitive series. Overall, we ascribe considerable potential to documentary records as climate data, especially in regions and seasons not well represented by early instrumental data and palaeoclimate proxies.
Quality control of stream water-stage using Hilbert-Huang Transform
Authors: Chen Yen- Chang , Hsiao Wu-Hsien
Published: February 2023

Hydrological data, especially water stage and discharge, is very important for water resources planning and development, hydraulic structure design, and water resources management. Thus the hydrological data has to be observed and collected regularly and continuously. The hydrological data can be affected by many factors such as people, instruments, and climate. Therefore, the collected hydrological data still need to be subject to quality control and inspection to eliminate unreasonable data to ensure the accuracy and reliability. Traditionally, the quality control and inspection of stream water-stage is mainly manual. The verification of water stage data needs experienced hydrologists to judge the correctness of the data, and cannot be processed automatically. It is time consumed, costly, and labor intensive to process the quality control of stream water stage. Therefore, it is necessary to develop a feasible model to automatically check stream water-stage for providing reliable and accurate hydrological data.This study applies Hilbert-Huang Transform (HHT) to process stream water-stage. The HHT is composed of Empirical Mode Decomposition (EEMD) and Hilbert transform (HT). The EEMD decomposes stream water-stage into many intrinsic mode functions (IMFs) and a residual. The first IMF component is used for Hilbert transform conversion to obtain the time amplitude energy relationship diagram. The amplitude fluctuation of the corresponding component of the stream water-stage, the amplitude value of the outliers can be revealed. When the amplitude value is larger than usual, there may be outliers, and vice versa. It depends on the threshold that is established in this study as the basis for filtering the incorrect water-stage. Therefore automatically inspecting the water-stage data can be achieved. The model for automatic inspecting procedure developed by this study will greatly reduce the manual quality control, not only shorten the checking time, save manpower, but also provide reliable and correct river water stage data.
Differential enrichment mechanism of organic matter under reduction conditions in freshwater and saline lakes
Authors: Liang Xinping
Published: February 2023

There are different mechanisms of reduction water column for the formation and preservation of organic matter during the depositional period of the continental lake basin. Therefore, determining the nature of the water column and its influencing factors is the key factor for differential enrichment of organic matter. In this study, by analyzing the TOC, mineral types, iron speciation, elements and isotopes characteristics of typical freshwater and saline lake organic-rich shales, the water column of synsedimentary environment of different lake shale deposits was compared. Our results show that the organic-rich shale of the Chang 7 Member (Ch7) of Yanchang Formation in the Ordos Basin and the Lucaogou Formation (P2l) in the Jimsar Sag of Junggar Basin in freshwater-saline environments have an intensity of sulfate reduction (BSR) (SRI < 1.375), the shales of Fengcheng Formation (P2f) in saline lake of the Mahu Sag in Junggar Basin have strong BSR (SRI > 1.375). This indicates that in ferruginous conditions the organic matter consumed by BSR is lower than the preserved organic matter, resulting a higher TOC content; in euxinic conditions caused by excessive volcanic activity or the input of hydrothermal fluids, a large amount of organic matter was degraded and consumed, causing more iron oxides (and other iron-containing minerals) dissolve gradually to form pyrite, reducing the TOC content. This study not only enabled to understand the shale oil enrichment, but also proposed a better theoretical and practical model for hydrocarbon accumulation in shale formations, to guide future shale oil exploration efforts.
Resolution of data, type of inventory and data splitting in machine learning-based landslide susceptibility mapping
Authors: Satyam Neelima , Abraham Minu Treesa , Gupta Kunal
Published: February 2023

The use of machine learning (ML) approaches for developing landslide susceptibility maps (LSM) has gained wide popularity in the recent past. The choice of ML algorithms, spatial resolution, the ratio of train-to-test data, and the landslide conditioning factors are some of the crucial factors that decide the performance of the developed LSM. However, there are no formal guidelines on the selection of any of these factors, as the choice highly depends upon the study area. In most cases, site-specific comparative analysis are required to find the best-suited combination. Two case studies were conducted for parts of the Western Ghats in India to develop pixel-based LSM for Idukki and Wayanad districts. Five different ML algorithms, two different spatial resolutions, multiple train-to-test ratios and two different types of landslide inventory data were used for developing the best-suited LSM. After detailed analysis, it was observed that the random forest (RF) algorithm has resulted in the best-performing LSM for both regions. The effects of spatial resolution and data splitting were found to be different for different algorithms, and among all the factors considered, data splitting is found to be the least influencing factor. 