bluuebunny/crossref_metadata_2025 huggingface dataset:
Long term (1930-2018) climate and snow cover trend in Val D’Ossola valley, Western Alps.
Authors: Stucchi Leonardo , Bocchiola Daniele , Dresti Claudia
Published: March 2022

Val d’Ossola is an alpine valley in the Western Alps, nesting some of the highest peaks of Italy (4609 m a.s.l.), and several snowfield and glaciers, providing freshwater in thaw season. Since the ’30s snow and ice melting were exploited largely for hydropower production, and climate stations were installed to monitor local climate and to help the assessment of production. Here, we exploited data from such stations, pursing statistical analysis of 2 dataset, i.e. i) Set1 with daily temperature T, precipitation P, and snow depth HS for 9 stations (1930-2018), and ii) Set2 with data of snow depth HS, and density ρS measured on a fortnight basis (1° February to 1° June) for 47 stations (2007-2021).

After preliminary data quality assessment, we pursued Mann Kendall (MK, bulk, and progressive) test and Linear Regression LR (with change point detection CP), to highlight in Set1 a positive/negative trend for temperature/snow depth.

The use of progressive MK and CP provided evidence of negative trends of HS (ca. -100 mm for annual peak), and snow cover duration DS (ca. -27 days per year) since the late ’80s. Spring/summer T is significantly correlated with retirement of a nearby Swiss glacier (Muttgletcher).

For Set2, with snow depth and density available, we found Snow Water Equivalent SWE = HS • ρs peaking nearby May 15th, more than one month later than the peak in snow depth HS (April 1st), displaying that decrease of HS in April is likely due to settling, rather than to mass loss by ablation. The seasonal peak of SWE is however delayed with altitude, namely by ca. 6 days later, every 100 m upward.

Our results match those from other studies in the Alpine area, and can be used as a benchmark for snow cover assessment under climate change, and study of seasonal water delivery in the Alps of Italy, and Europe
Carbon budgets from global to regional scales: current challenges and future perspectives
Authors: Bastos Ana
Published: March 2022

To fulfill the international objective “…to reach global peaking of greenhouse gas emissions as soon as possible … and to undertake rapid reductions thereafter in accordance with best available science...to achieve a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century”, the Paris Agreement implemented the Global Stocktake Process to assess regularly the world’s collective progress towards achieving the purpose of the agreement and its long-term goals.

National greenhouse gas (GHG) inventories report only anthropogenic fluxes. However, many GHG sources are difficult to separate from the natural fluxes. Moreover, inventories cannot easily be scaled to the globe given the use of different approaches for GHG budgeting but, more importantly, because the states of the natural ocean and land sinks are not considered. Fast developments in the scientific capabilities to quantify GHG budgets and their trends consistently from the global to the national scale as well as accurate attribution of budgets to natural and anthropogenic processes are needed.

In Global Carbon Budgets top-down and bottom-up estimates still show large discrepancies at regional or country scale, due to large and multiple sources of uncertainty. Reducing these uncertainties and improving regional GHG budgets is currently the focus of the second “REgional Carbon Cycle Assessment and Processes” (RECCAP-2) initiative supported by the Global Carbon Project. This effort is fueled by an ever-expanding constellation of and in-situ and satellite-based GHG observations, and by increased process-based and data-driven modelling capabilities.

Here, I will discuss some of the elements that still challenge our ability to robustly link global to the regional and country carbon budgets, and their implications for the Global Stocktake. I will then show recent examples on how multi data-stream approaches can be used to identify and understand sources of discrepancies between top-down and bottom-up estimates and to improve attribution of regional carbon budgets to specific natural and anthropogenic processes.  
Flow and residence time in a laboratory aquifer recharged by rainfall
Authors: Lajeunesse Eric , Devauchelle Olivier , Jules Valentin , Guérin Adrien , Jaupart Claude , Lagrée Pierre-Yves
Published: March 2022

During rainfall, water infiltrates the soil, and percolates through the unsaturated zone until it reaches the water table. Groundwater then flows through the aquifer, and eventually emerges into streams to feed surface runoff. We reproduce this process in a  two-dimensional laboratory aquifer recharged by artificial rainfall (Fig. 1). As rainwater infiltrates, it forms a body of groundwater which can exit the aquifer only through one of its sides. The outlet is located high above the base of the aquifer, and drives the flow upwards. The resulting vertical flow component violates the Dupuit-Boussinesq approximation. In this configuration, the velocity potential that drives the flow obeys the Laplace equation, the solution of which crucially depends on the boundary conditions. Noting that the water table barely deviates from the horizontal, we linearize the boundary condition at the free surface, and solve the flow equations in steady state. We derive an expression for the velocity potential, which accounts for the shape of the experimental streamlines and for the propagation rate of tracers through the aquifer  (Fig. 1). This theory allows us to calculate the travel times of tracers through the experimental aquifer, which are in agreement with the observations. The travel time distribution has an exponential tail, with a characteristic time that depends on the aspect ratio of the aquifer. This distribution depends essentially on the geometry of the groundwater flow, and is weakly sensitive to the hydrodynamic dispersion that occurs at the pore scale.

 

<img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gepj.6f34b8843dd166586881461/sdaolpUECMynit/22UGE&app=m&a=0&c=554c54a03c40da7640dce6840774f5d0&ct=x&pn=gepj.elif&d=1" alt="" width="373" height="264">

Figure 1 : Streamlines in a laboratory aquifer recharged by artificial rainfall. Flow is from left to right. The streamlines converge towards the aquifer outlet, in the upper right corner of the picture.
Diahaline Mixing and Exchange Flow in A Large Multi-outlet Estuary with Islands
Authors: Li Xiangyu , Lorenz Marvin , Klingbeil Knut , Chrysagi Evridiki , Gräwe Ulf , Wu Jiaxue , Burchard Hans
Published: March 2022

The relationship between the diahaline mixing, the diffusive salt transport, and the diahaline exchange flow is examined using salinity coordinates. The diahaline inflow and outflow volume transports are defined in this study as the integral of positive and negative values of the diahaline velocity. A numerical model of the Pearl River Estuary (PRE) shows that this diahaline exchange flow is analogous to the classical concept of estuarine exchange flow with inflow in the bottom layers and outflow at the surface. The inflow and outflow magnitudes increase with salinity, while the net transport equals the freshwater discharge Qr after sufficiently long temporal averaging. In summer, intensified diahaline mixing mainly occurs in the surface layers and around the islands. The patchy distribution of intensified diahaline velocity suggests that the water exchange through an isohaline surface can be highly variable in space. In winter, the zones of intensification of diahaline mixing occur mainly in deep channels. Apart from the impact of freshwater transport from rivers, the transient isohaline mixing is also controlled by an unsteadiness term due to estuarine storage of salt and water volume. In the PRE, the diahaline mixing and exchange flow show substantial spring-neap variation, while the universal law of estuarine mixing m=2SQr (with m being the sum of physical and numerical mixing per salinity class S) holds over longer averaging period (spring-neap cycle). The correlation between the patterns of surface mixing, the vorticity, and the salinity gradients indicates a substantial influence of islands on estuarine mixing in the PRE. 
A comparative study of riverine 137Cs dynamics during high-flow events at three contaminated river catchments in Fukushima
Authors: Wakiyama Yoshifumi , Niida Takuya , Takata Hyoe , Taniguchi Keisuke , Kurosawa Honoka , Fujita Kazuki , Konoplev Alexei
Published: March 2022

This study presents the temporal variations in riverine 137Cs concentrations and fluxes to the ocean during high-flow events in three coastal river catchments contaminated by the Fukushima Daiichi Nuclear Power Plant accident. River water samples were collected at points downstream in the Niida, Ukedo, and Takase Rivers during three high-flow events that occurred in 2019–2020. Variations in both the dissolved 137Cs concentration and 137Cs concentration in suspended solids appeared to reflect the spatial pattern of the 137Cs inventory in the catchments, rather than variations in physico-chemical properties. Negative relationships between the 137Cs concentration and δ15N in suspended sediment were found in all rivers during the intense rainfall events, suggesting an increased contribution of sediment from forested areas to the elevated 137Cs concentration. The 137Cs flux ranged from 0.33 to 18 GBq, depending on the rainfall erosivity. The particulate 137Cs fluxes from the Ukedo River were relatively low compared with the other two rivers and were attributed to the effect of the Ogaki Dam reservoir upstream. The ratio of 137Cs desorbed in seawater to 137Cs in suspended solids ranged from 2.8% to 6.6% and tended to be higher with a higher fraction of exchangeable 137Cs. The estimated potential release of 137Cs from suspended solids to the ocean was 0.048–0.57 GBq, or 0.8–6.2 times higher than the direct flux of dissolved 137Cs from the river. Episodic sampling during high-flow events demonstrated that the particulate 137Cs flux depends on catchment characteristics and controls 137Cs transfer to the ocean. 
Environmental evolution and Landslide hazard assessment based on UAS multi-sensors 
Authors: Chang Kuo-Jen , Tseng Chun-Wei , Hsieh Yu-Chung , Huang Mei-Jen
Published: March 2022

Taiwan, due to the high seismicity and high annual rainfall, numerous landslides triggered frequently, thus caused severe social impacts. Landslides pose long-lasting threats to humans and their property and are detrimental to the environment in general. The vigorous development of geospatial information technology has not only achieved good results in land monitoring, but has also been gradually extended to other application fields. Hazards monitoring is one of the important applications. Geospatial information can be obtained through surveying and mapping technology, and through multi-temporal geospatial data, the production, migration and migration of debris deposits can be quantitatively evaluated in a reasonable time and space in catchment scale. In recent years, the development and integration of MEMS technology has contributed to the rapid development of UAV measurement. This goal can be achieved due to the advantages of UAVs, such as efficiency, timeliness, low cost, and easy operation in severe weather conditions. The real-time, clear and comprehensive low- and middle-altitude photos of the area can be used as the most basic and important spatial information for research and analysis.

Based on the aforementioned technologies, some specific potential landslides situated in the Laonongshi Stream southern Taiwan was been assigned. In order to evaluate potential hazards and hazard monitoring, multi-temporal high precision terrain geomorphology in different periods is essential. For these purpose, we integrate several technologies, especially by unmanned aircraft system imageries and existed airphotos, to acquire and to establish the geoinfomatic datasets. The methods, including, (1) Remote-sensing images gathered by UAS and by aerial photos taken in different periods; (2) UAV LiDAR acquired in different periods; (3) field in-situ ground control points and check points installation and geomatic measurement; (4) 3D geomorphological virtual reality model construction; (5) Geologic, morphotectonic and landslide micro-geomorphologic analysis; (6) DEM of difference from multi-temporal dataset to evaluate the topographic and environment changes. We focused on the potential large-scale deep-seated landslides, acquired high-precision and high-resolution DTMs, proving as the essential geoinformatic datasets, so as able to monitoring the slope behavior and to decipher the potential landslide hazard, sediment budgets and the consequence of social impact. The results show that there are still landslide activities in different periods and regions within the study area; different sections of the river channel also have different degrees of siltation or erosion. Therefore, regular monitoring and potential assessment are necessary. The developing methods may apply for other potential large-scale landslide monitoring and assessment in Taiwan, and in world as well.
Ground-based GNSS data processing for atmospheric water vapor retrieval at Wuhan University and some applications
Authors: Zhang Weixing , Lou Yidong , Zhou Yaozong , Li Xianjie , Bai Jingna , Zhang Zhenyi
Published: March 2022

Wuhan University has joined the E-GVAP program as one of the analysis centers (ACs) since 2019. Data at about 300 global GNSS stations are routinely processed in near-real-time at Wuhan University for tropospheric delay product. Both the single GPS solution and the recent multi-GNSS (GPS/GLONASS/Galileo/BDS) solution have been delivered to E-GVAP. Besides the near-real-time processing, we also work on the long-term historical data reprocessing for climate research and on the real-time processing for atmospheric monitoring. In the reprocessing work, by taking the recent ERA5 and homogenized radiosonde data as reference, we have made comprehensive investigations on the impacts of different models (e.g., the mapping function) and settings (e.g., the cut-off elevation angle) using global data of more than two decades. The long-term water vapor product was used for climate analysis and for inter-comparisons among different techniques (GNSS, radiosonde, reanalysis, MODIS, etc.). In the real-time processing work, we have carried out a four-month real-time water vapor retrieval campaign in three cities of China in 2021 by including the latest BeiDou-3 satellites and by using the high-accuracy satellite product transmitted by BeiDou-3 GEO satellites on the B2b signal. The data processing work in reprocessing, near-real-time and real-time modes at Wuhan University will be systematically introduced and some applications in climate research and atmospheric monitoring will be presented.
The Three-Dimensional Internal Tide Radiation andDissipation in the Mariana Arc-Trench System
Authors: Zhao Chen , Xu Zhenhua , Robertson Robin , Li Qun , Wang Yang , Yin Baoshu
Published: March 2022

  Internal tides are energetic in the Mariana arc, but their three-dimensional radiation and dissipation remain unexplored, particularly the trench-arc-basin impacts. Here, the generation, propagation and dissipation of M2 internal tides over the Mariana area are examined using a series of observation-supported high-resolution simulations. The M2 barotropic to baroclinic conversion rate amounts to 8.35 GW, of which two arc-shaped ridges contribute ~81% of the generated energy. The contributions to generation by the Mariana basin and deep trench are weak. Nevertheless, they are important in modulating the energy radiation and dissipation, since tidal beams can spread to these areas. The Mariana ridges radiate the westward-focused and eastward-spreading tidal beams. This is very consistent with the altimetric measurements. The resonance in the ridge center enhances the westward converging beam, which can travel across the Palau Ridge, 800 km away. In contrast, the eastward beams propagate over a limited lateral range, but can radiate and dissipate significant energy in the deep water column, reaching even to the abyssal Mariana trench. The direct estimation from the model results reveals the dissipation’s multilayer vertical profile in the entire water column, and is well consistent with the finescale parameterization estimate based on vertical strain. However, the estimate of an oft-used energy balance method, which typically assumes an exponentially decaying vertical structure function for the dissipation rate based on distance above the seafloor, is largely inconsistent with the measurements. Our findings highlight the complexity of three-dimensional radiation paths and dissipation map of internal tides in the Mariana area.
Impact of secondary organic aerosol on climate over East Asia for 1980–2020
Authors: Yang Seohee , Park Rokjin , Lee Seungun , Jo Duseong , Kim Minjoong
Published: March 2022

 Secondary organic aerosol (SOA) is produced through photochemical reactions between volatile organic compounds and oxidants in the atmosphere. SOA may have a strong climatic effect because it contains not only colorless carbon, which merely scatters light, but also colored carbon, which can absorb light. However, the climatic effect of SOA is still unclear because the coupled climate−atmospheric chemistry model has limitations in SOA simulation owing to the chemical complexity and high computing power consumption. Therefore, it is necessary to examine the long-term climate effects of SOA through a sophisticated SOA scheme. In this study, we investigate the effect of SOA on climate in East Asia using a long-term simulation by coupling the SOA scheme in the climate−atmospheric chemistry model. We developed an SOA module for the climate model that minimizes chemical processes and computing power consumption through parameterization using empirical parameters. The simulated SOA suitably captured the observed SOA, indicating that the SOA scheme is successfully coupled in the climate−atmospheric chemistry model. We conducted a control and two sensitivity simulations with four ensemble simulations for 1980–2020 to investigate the effect of whole radiative and only absorptive forcing of SOA on climate in East Asia. Climate change in the control simulation for 1980–2020 is much closer to reanalysis data than sensitivity simulation, implying a large contribution of SOA on East Asian climate in recent decades. Sensitivity simulation suggests that the light absorption of SOA affects the East Asian climate, causing an increase in temperature at the surface and a decrease in atmospheric stability. Considering that the simulated SOA concentration shows a noticeable increasing trend in East Asia over recent decades, our results imply that SOA has had a significant impact on long-term climate change over East Asia. Therefore, SOA simulation should be included in climate simulations in East Asia.
State-dependent effects of natural forcing on global and local climate variability 
Authors: Ellerhoff Beatrice , Kirschner Moritz J. , Ziegler Elisa , Holloway Max D. , Sime Louise , Rehfeld Kira
Published: March 2022

Climate variability is the primary influence on climate extremes and affected by natural forcing from solar irradiance and volcanic eruptions. Global warming impacts climate variability, but there is contradictory and incomplete evidence on the spatio-temporal patterns. Strong volcanic eruptions have been suggested to reduce temperatures less in warmer climate states. However, the underlying question of state-dependent effect of natural forcing on local and global variability remains open. Moreover, there are uncertainties about the role of natural forcing in the mismatch between simulated and reconstructed local, long-term variability.  

Using a 12-member GCM ensemble with targeted boundary conditions, we present naturally-forced and equilibrium, millennium-length simulations for the Last Glacial Maximum (LGM) and the Pre-Industrial (PI). We quantify the local and global climate response to solar and volcanic forcing in the LGM and PI, and contrast variability from forced and control simulations on annual-to-multicentennial scales. We differentiate various contributions from the atmosphere, oceans, and particularly that of sea ice using a 2D energy balance model (EBM). Spectral analysis of simulated temperatures shows that global variability is predominately determined by natural forcing. Local mean spectra are more characteristic for the mean climate state and reveal a decrease in local variability with warming. The global and local response to natural forcing is robust against changes in the mean climate. Particularly, the spatial patterns of the surface climate's response to volcanic eruptions widely agree across states. Weak local differences resulted primarily from sea ice dynamics. The sea ice contribution is the strongest on interannual scales. It remains significant on decadal scales and longer, providing a key mechanism of long-term variability. We validate the simulated variability against observational and paleoclimate data. The variance obtained from proxies is increasingly larger on longer timescales compared to that from simulated time series. The inclusion of natural forcing reduces the model-data mismatch on decadal-to-multicentennial scales and, thus, provides a more accurate representation of climate variability. 

Consideration of natural forcing is therefore paramount for model-data comparison and future projections. The robust temperature response suggests that findings on the ability of models to simulate past variability should translate to future climates, and can thus help constrain variability. 
Temporal variability of Multimodal Internal Tides at the East China Sea Shelf
Authors: Wang Weidong , Robertson Robin , Wang Yang , Zhao Chen , You Jia , Xu Zhenhua , Yin Baoshu
Published: March 2022

Internal tide variations and mixing properties are important to shelf dynamics and mass exchange. In the present study, spatiotemporal variability of internal tides and their modulation factors on the southern East China Sea (ECS) shelf are examined using a three-month mooring observation. Semidiurnal and diurnal internal tides are found to exhibit distinct varying trends. Specifically, the semidiurnal internal tides are quite weak at the early stage, but greatly enhanced in the last three spring-neap cycles. In contrast, the diurnal internal tides follow quasi spring-neap variability except for the strengthening in two specific periods. The enhancement of semidiurnal internal tides in late July and August can be attributed to the strengthened stratifications shelf-slope area northeast of Taiwan Island, which is identified as the generation source. While the diurnal internal tides are modulated by background circulation through the effective critical latitude. The weak critical latitude effect corresponds to the intermittent enhancement of diurnal internal tides in two specific periods. In addition, the circulation also affects the vertical modal structures of the internal tides. The proportion of higher modes internal tides increases during robust eddy activities.  The high-frequency and high-mode internal tides are of crucial significance for turbulent mixing on the shelf region.

Key word: Internal Tides; Mooring Observation; Spatiotemporal variation; Shelf dynamics
Widely-spaced Double Hotspot Chains due to Forked Plumes sample Lower Mantle Geochemical Structure 
Authors: Ballmer Maxim , Finlayson Valerie
Published: March 2022

Age-progressive volcanic “hotspot” chains result from the passage of a tectonic plate over a thermochemical mantle plume, thereby sampling the otherwise-inaccessible lowermost mantle. A common feature in oceanic hotspot tracks is the occurrence of two parallel volcanic chains with an average separation of ~50 km (e.g., Loa and Kea chains in Hawaii). Some other tracks (including Tristan-Gough, Shona, the Line Islands, Wake seamounts, Tuvalu and Cook-Austral) feature a 200-400 km spacing, but the origin of such widely-spaced melting zones in the mantle remains unknown. Here, we explore 3D Cartesian geodynamic models of thermochemical plume ascent through the upper mantle. We explore various distributions of intrinsically-dense eclogitic material across the plume stem. For a wide range of eclogite distributions, the plume pools in the depth range of 300~410 km, where the excess density of eclogite is greater than above and below, as also predicted by Ballmer et al., EPSL 2013. This “Deep Eclogitic Pool” then splits up into two lobes that feed two separate shallow plumelets, particularly at high eclogite contents in the center of the underlying plume stem. The two plumelets feed two separate melting zones at the base of the lithosphere, which are elongated in the direction of plate motion due to interaction with small-scale convection. This “forked plume” morphology can account for hotspot chains with two widely-spaced (250~400 km) tracks and with long-lived (>5 My) coeval activity along each track. Forked plumes may also provide an ideal opportunity to study geochemical zonation of the lower-mantle plume stem, as each plumelet ultimately samples the opposite side of a deep plume conduit that potentially preserves spatial heterogeneity from the lowermost mantle. We compare this model to geochemical asymmetry evident along the Wake, Tuvalu and Cook-Austral double-chain segments, which make up the extensive (>100 Ma) Rurutu-Arago hotspot track. The preservation of a long-lived NE-SW geochemical asymmetry along the Rurutu-Arago double chain indicates a deep origin, likely from the southern boundary of the Pacific large low shear-velocity province. Our findings highlight the potential of the hotspot geochemical record to map lower-mantle structure over space and time, complementing the seismic-tomography snapshot.
The role of coronal shocks for accelerating solar energetic electrons
Authors: Dresing Nina , Kouloumvakos Athanasious , Vainio Rami , Rouillard Alexis
Published: March 2022

We study the role of Coronal Mass Ejection (CME)-driven shocks in the acceleration of solar energetic electrons. Using observations by the two STEREO spacecraft, we correlate electron peak intensities of solar energetic particle events measured in situ with various parameters of the associated coronal shocks. These shock parameters were derived by combining 3D shock reconstructions with global modeling of the corona. This technique provides also shock properties in the specific shock regions that are magnetically connected to the two STEREO spacecraft. We find significant correlations between the peak intensities and the Mach number of the shock with correlation coefficients of about 0.7, which are similar for electrons at ∼ 1 MeV and protons at > 60 MeV. Lower energy electrons < 100 keV show a smaller correlation coefficient of 0.47. The causal relationship between electron intensities and the shock properties is supported by the vanishing correlations, when peak intensities at STEREO-A are related with the Alfvénic Mach numbers at the magnetic footpoint of STEREO-B and vice versa, which yields correlation coefficients of 0.03 and -0.13 for ∼ 1 MeV and < 100 keV electron peak intensities, respectively. We conclude that the high-energy electrons are accelerated mainly by the shock, while the low energy electrons are likely produced by a mixture of flare and shock-related acceleration processes.
What do CMIP6 models tell us about rainfall intensification in the West African Sahel?
Authors: Chagnaud Guillaume , Panthou Geremy , Vischel Theo , Lebel Thierry
Published: March 2022

Regional projections of rainfall changes are required for adaptation planning, especially in regions where unprecedented climatic evolution are underway, such as the West African Sahel. The potential of models to draw a realistic picture of future regional changes remains to be assessed through the lens of past evolution. Here we make sense of several rainfall regime indicators, a widespread raingauge dataset and a set of the most recent climate model simulations to identify features that deserve confidence and others that require care. We show that, at the sahelian scale, the mean intensity and occurrence of rainy days are well reproduced, yielding a good depiction of the recent rainfall intensification. However, unlike wet extremes, changes in dry extremes are not captured, pointing to model deficiencies in reproducing realistic changes in intraseasonal rainfall variability. We also show that the regional rainfall evolution of the last 35 years is very unlikely due to neither internal variability nor to natural forcing factors alone; based on a qualitative attribution analysis, aerosols turn out to account for the largest share of the recent increasing signal. The greenhouse-gases (GHG) influence makes less consensus among models, especially regarding extreme rainfall trends. This is a major concern for projections of future hydro-climatic trajectories in the region since GHG is to become the predominant climate forcing factor for the coming decades.
Sea surface temperature seasonality in northern South China Sea during the middle Holocene derived from high resolution Sr/Ca ratios of Tridacna shells
Authors: Zhou Pengchao , Yan Hong , Ge Shi , Liu Chengcheng , Fan Luo , Tao Han , Wang Guozhen , Wen Hanfeng , Zhao Nanyu , Dodson John , Li Yue , Zhou Weijian
Published: March 2022

Seasonal climate variability is an important component of the climate system, and has a significant impact on ecosystems and social systems. However, the temporal resolution of most proxy-based paleoclimate records is limiting to fully understand the past seasonal changes. Here we used high-precision monthly resolution Sr/Ca records of three Tridacna squamosa from northern SCS to reconstruct the SST seasonality during three-time windows of the middle Holocene. The results suggested that the SST seasonality in northern SCS during the middle Holocene (3.21 ± 0.98℃) was smaller than that for recent decades (1994-2004 AD, 4.32 ± 0.59℃). The analysis of modern instrumental data showed that the SST seasonality in northern SCS was dominated by the winter SST, which was deeply influenced by the intensity of EAWM. Strong EAWM usually resulted in cooler winter SST and a larger SST seasonality in northern SCS. The reconstructed Holocene EAWM records showed that the EAWM strengthened from the middle to late Holocene, which could be demonstrated by our reconstruction of a smaller SST seasonality during the middle Holocene in northern SCS. This study highlighted that the Sr/Ca ratios of Tridacna shells can be used as a potential high-resolution indicator of past seasonal climate changes.
Data-driven modelling of the evolution of CME properties in the low-corona: AR12473
Authors: Wagner Andreas , Kilpua Emilia , Price Daniel J. , Pomoell Jens , Kumari Anshu , Daei Farhad , Sarkar Ranadeep
Published: March 2022

To better predict the impacts of solar eruptions on Earth, understanding the low-corona evolution of CMEs is crucial because this influential early phase is highly dynamic. We therefore investigate the evolution of CME properties, such as the evolution of flux rope footpoints as well as the magnetic flux enclosed in the flux rope, during this stage of the eruption. To simulate the eruption we make use of the data-driven time-dependent magnetofrictional method (TMFM), which has been proven to accurately capture a flux rope's early evolution and lift-off. We then developed a semi-automatized method for identifying the flux rope and extracting these flux ropes from 3D data cubes and tracking their evolution in time. The extraction algorithm is based on the twist parameter Tw in a 2D plane close to the polarity inversion line as a proxy for the flux rope and its temporal evolution. It is then applied to TMFM simulations of the active region AR12473, which produced an eruption on 28th of December 2015 (see e.g., Price et al, 2020). This CME was also accompanied by an M1.9 flare, that peaked at about 12:45 UT. The extracted flux rope footpoints are then compared against observational data from SDO's AIA instrument in the 1600 Å wavelength. This comparison yields a very good match with coverage parameters (see Asvestari et al, 2019) in the range of 60-70 %. The magnetic flux is extracted from the footpoints that are rooted in one specific polarity region. 
Research progress of soil erosion in Pisha stone area of Yellow River
Authors: shen zhenzhou
Published: March 2022

The soil-covered Pisha stone area is the core source area of coarse sediment in the Yellow River and has become the focal point of ecological control of the Yellow River Basin. It is thus vital to study the spatial distribution of erosion coupling between geomorphology, vegetation, and water in the soil-covered Pisha stone area. Some valuable research results have been obtained already by using high-definition remote sensing aerial photographs and-high precision data from unmanned aerial vehicles. In particular, the image resolution obtained by unmanned remote sensing reveals small watershed topographic features and the characteristics of vegetation structure. Thus, the use of remote sensing is vital for research involving the spatial distribution of soil erosion in the slopes of the Pisha stone area and the dynamics of the geomorphic spatial structure of the slopes. In addition, the negative correlation between the spatial structure of the vegetation community and the energy dissipation impedance of erosion requires further study. Research into soil erosion in the Pisha stone area thus represents an urgent scientific need whose outcome will directly affect the theoretical foundation of a comprehensive model for treating soil erosion in this area.
SANS: Publicly available daily seismic ambient noise source maps on a regional to global scale
Authors: Igel Jonas , Bowden Daniel , Fichtner Andreas
Published: March 2022

To improve methods in full-waveform ambient noise tomography and monitoring it is important to have knowledge of the spatio-temporal variations of the noise source distribution. Without this knowledge, an uneven distribution of sources may bias observations, and a changing source distribution may be falsely interpreted as subsurface velocity changes. By combining two methods to locate noise sources and decreasing the computational cost, we are able to invert for the global noise source distribution of the secondary microseisms on a daily basis. Additionally, we present a web framework where the Seismic Ambient Noise Source (SANS) maps are made available to the public. 

Many different methods to locate ambient noise sources have been developed. Bowden et al. (2021) show how a more data-driven Matched-Field Processing (MFP) approach and a more rigorous finite-frequency sensitivity kernel method can be derived from one another.  Igel at al. (2021) implement spatially variable grids and pre-computed wavefields to make the finite-frequency inversion more efficient. This has made daily inversions on a regional to global scale feasible for secondary microseismic noise sources in a frequency range from 0.1 to 0.2 Hz. Since the inversion approach allows for prior information to be implemented, we use the more efficient MFP method to create an initial model and steer the inversion in the right direction. 

In collaboration with the Swiss National Supercomputing Centre (CSCS) we are able to run this workflow on a daily basis. The resulting noise source maps are subsequently made available to the public through our web framework SANS. A user can look through all iterations of the inversions, download all model and inversion files, and implement them in their own methods. Additionally, code is provided to help the user create plots and simplify the implementation in other studies. We are looking for collaboration with ambient noise tomography studies to investigate how the implementation of noise source maps could potentially improve the resulting structure models.
Volatile carbon emissions from a degrading permafrost peatland
Authors: Jiao Yi , Davie-Martin Cleo , Kramshøj Magnus , Christiansen Casper , Lee Hanna , Althuizen Inge , Rinnan Riikka
Published: March 2022

Permafrost in the north Polar Regions stores more than 1,500 Pg of organic carbon, which is nearly twice as much as the atmospheric carbon pool. As the Arctic region is experiencing unprecedented warming, accelerated decomposition in permafrost is potentially switching it to a hotspot of carbon emissions. In addition to the widely studies carbon dioxide and methane, permafrost may also be a source of biogenic volatile organic compounds (BVOCs), a reactive group of trace gases which have so far received much less attention. BVOCs can prolong the lifetime of methane through the depletion of hydroxyl radicals, contribute to ozone formation, and lead to the formation of secondary organic aerosol, and thus exert significant impact on climate forcing, especially in unpolluted Arctic region.

Here, we conducted in situ measurements of soil BVOC emissions on an actively degrading permafrost peatland during a growing season. We compared emissions along a gradient of landscape units from soil palsa and vegetated palsa to thaw slump, thaw pond and vegetated thaw pond. BVOC samples were collected onto absorbent cartridges using dynamic enclosure chamber method, and then analyzed with a gas chromatograph coupled with a mass spectrometer (GC/MS), based upon which the emission rates were calculated.

Results suggested that all landscapes units across the peatland showed net emissions of BVOCs during the summertime. Major BVOC groups included monoterpenes, sesquiterpenes, isoprene, hydrocarbons, methanol, acetone, other oxygenated VOCs and other compounds, and these groups were present in all landscape units. All VOC groups also exhibited seasonal and spatial variations across the different sampling months and landscape units. For example, the actively degrading thaw slump showed higher monoterpene emissions that other landscape units, while sesquiterpene emissions were highest from the vegetated thaw ponds. Principal component analysis further revealed temporal and spatial patterns in the relative compositions of the BVOC profiles. Our results show that soil BVOC emissions change in response to active permafrost thaw.
The neglected role of karst features in rock mass characterization and stability assessment
Authors: Loiotine Lidia , Andriani Gioacchino  Francesco , Derron Marc-Henri , Jaboyedoff Michel , Lollino Piernicola , Parise Mario
Published: March 2022

Stability analyses in karst settings, whether to assess the equilibrium conditions of natural slopes or to design engineering interventions, coexist with a significant uncertainty related to difficulties in modelling karst features. As a matter of fact, most of the rock mass classification systems do not directly take into account the presence of karst structures such as voids, conduits or caves, which can strongly influence the mechanical behaviour and the water flow in rock masses.

In the last decades, the identification and characterization of discontinuity systems for rock mass characterization, aimed at stability analyses, have been intensively investigated by means of remote sensing techniques. However, semi-automatic or automatic methods for the extraction of discontinuities from point clouds are not easily applicable in karst because surface and subsurface features produce irregular surfaces, which are difficult to classify even using the most-advanced algorithms. This occurs even more heavily in the case of soft rocks, such as calcarenites.

In this study, a demonstration of the influence of karst features in rock mass characterization and slope stability assessment is presented. First, the results of the Discontinuity Set Extractor (DSE) software used on an appropriate case study show that the irregular surfaces produced by carbonate dissolution, further enhanced by weathering, caused an incorrect classification of the discontinuity sets. Second, a high-resolution Digital Outcrop Model (DOM) was used to generate a very fine mesh (average element size = 35 cm, to take into account the large-scale karst structures) and to carry out 3-D numerical stability analyses by means of Finite Element Method, using a continuum-based approach. Although in the current conditions the examined slope is stable, the results illustrate that the maximum shear strain is localized in correspondence of the karst features (e.g. caves and voids) and at the sea level. By applying the Shear Strength Reduction method, it was found out that weathering processes can cause the same structures to be under yield and lead to localized failures.

In addition, the key role that the discontinuities (extracted using an ad-hoc procedure) play on the rock mass mechanical behaviour was investigated using a 2-D FEM, based on a discontinuum approach. The results, which are in agreement with field observations, point out that karst processes, which features are characterized by the highest values in pervasiveness and aperture of the discontinuity systems and tend to reduce the rock bridges over time, need to be implemented in the rock mass classification systems and in numerical modelling techniques to avoid incorrect results. 
20 Years of Cluster Observations: The Magnetopause
Authors: Haaland Stein , Hasegawa Hiroshi , Paschmann Goetz , Sonnerup Bengt , Dunlop Malcolm
Published: March 2022

The terrestrial magnetopause forms the boundary between the solar wind plasma with its embedded interplanetary magnetic field on one side, and the terrestrial magnetosphere, dominated by Earth's dipole field, on the other side. It is therefore a key region for the transfer of mass, momentum, and energy from the solar wind to the magnetosphere. The Cluster mission, comprising a constellation of four spacecraft flying in formation was launched more than 20 years ago to study boundaries in space. During its lifetime, Cluster has provided a wealth of new knowledge about the magnetopause. In this presentation, we give an overview of Cluster-based studies of this boundary, and highlight a selection of interesting results. 
Modeling water trading to support integrated green infrastructure and water resources management in an arid watershed
Authors: Zhang Mengxiang , Chui Ting Fong May
Published: March 2022

Developing green infrastructures (GIs) for rainwater harvesting has prevailed in many arid regions, which requires a new water management framework. This paper focuses on a water policy - water trading scheme – design and analysis for integrated green infrastructures and water resource management in a watershed that consists of multiple urban areas. A multiagent model bringing together urban water management and GIs planning models for multiple water managers with hydrological models is proposed to show 1) what the optimized water trading scheme is, 2) how the scheme would affect watershed socio-hydrologic environments, and 3) what the role of GIs in the scheme is. In the model, the water trading scheme design depends not only on the hydrologic dynamics of watershed caused by GIs and but on the social interactions between watershed and multiple urban managers. The proposed model is applied to the Colorado River Lower Basin, which is one of the USA's aridest regions and is planning water trading. Results indicated that a water-trading scheme effectively allocates limited water resources with a minimized system cost in the study area. Results also show that developing GIs to use rainwater resources might further reduce the cost induced by the water trading scheme. However, it might also exacerbate water resource allocation inequity among water users. These findings can help decision-makers design the associated water policy to support sustainable watershed development in arid regions.
Transport and deposition of plastic particles in porous media during seawater intrusion and groundwater-seawater displacement processes
Authors: li meng , tong meiping
Published: March 2022

Visible flow chamber systems packed with porous media (at both macroscale and pore scale) and packed column systems for the first time were used to systematically investigated the impacts of seawater intrusion and groundwater-seawater displacement on the transport behaviors of marine plastic particles with different sizes in porous media. We found that seawater intrusion could transfer all three sized plastics into coastal porous media and their transport would be affected by seawater flow velocity. For example, 8.5%, 24.8%, 39.8% of 1 mm plastic particles could pass through the columns during the 10, 50 and 250 m/d seawater intrusion processes, respectively. The groundwater-seawater displacement process could re-mobilize plastic particles pre-attached onto sand. The percentages of released plastic particles were negatively correlated with the sizes of plastic particles and the ionic strength of displacement groundwater. Groundwater velocity did not obviously affect the release of plastic particles from sand. The percentage of released plastic particles were affected by seawater intrusion cycles. XDLVO was employed to theoretically explain the transport behaviors of plastic particles under different conditions. Our study showed that seawater intrusion would transfer marine plastic particles into coastal aquifer and groundwater-seawater displacement could affect the release of plastic particles from porous media.
Motianling peatland, a typical ombrotrophic bog in China documents the anthropogenic impact history during the past centuries
Authors: Bao Kunshan
Published: March 2022

Ombrotrophic peat bogs are hydrologically isolated from the inﬂuence of local ground and surface waters and are fed exclusively by atmospheric deposition consisting of both solid particles and mineral substances dissolved in rain water. They have the advantage of widespread distribution and the physical and chemical properties of peat contribute to effective trapping and immobilization of atmospherically deposited solutes and particles. As a result, ombrotrophic peat can offer valuable opportunities to explore past atmospheric environmental conditions. Peatlands are widely distributed in China, including the Qingzang Plateau in the southwest and the mountains and plains in the northeast. However, the typical ombrotrophic peatlands with low ash content and rainfed characters are not common. The Motianling peatland in Aershan of Great Hinggan Mountains is in the most northern part of China that belongs to a moderate, cold climate with the domination of westerlies. This peatland has a well-established trophy status and its ombrotrophic character has been verified by multi-proxies. It has previously been studied to assess the levels of Pb and Hg pollution and dust deposition. To the best of our knowledge, Motianling peatland is one of the most typical ombrotrophic bog in China and its geochemical signatures document the anthropogenic impact history during the past centuries.