bluuebunny/crossref_metadata_2025 huggingface dataset:
Controls on early-stage, magma-poor rifting from top-to-bottom seismic imaging of the Malawi (Nyasa) Rift
Authors: Shillington Donna , Gaherty James , Scholz Christopher , Nyblade Andrew , Chindandali Patrick , Wambura Ferdinand Richard , Mbogoni Gabriel , Hopper Emily , Accardo Natalie , Tepp Gabrielle , Grivalja Ashley , Borrego David , Mulibo Gabriel
Published: March 2022

Few constraints are available on variations in extension with depth and along-strike in early stage continental rift systems, leaving many questions on the mechanisms of extension and the controlling factors. The Malawi (Nyasa) Rift in the southern East Africa Rift System exemplifies an active, magma-poor, weakly extended continental rift. Between 2014-2016, we collected a multi-faceted, amphibious, active- and passive-source seismic dataset across the northern Malawi Rift as a part of the SEGMeNT (Studies of Extension and maGmatism in Malawi aNd Tanzania) interdisciplinary experiment. Together, analysis and integration of these seismic imaging datasets provide a comprehensive portrait of the style and amount of stretching throughout the lithosphere and along strike.  Broadband scattered-wave imaging and wide-angle seismic reflection/refraction data reveal substantial variations in extension with depth, with much more thinning of the lithospheric mantle than the crust (stretching factors of 3.8 and 1.7, respectively). The modest observed reduction in velocity below the rift from both broadband surface- and body-wave imaging can be explained with small thermal perturbations and without melt. Lower velocities and complex patterns of anisotropy underlie the Rungwe Volcanic Province to the north of the Malawi Rift, suggesting focused lithospheric modification, melting and complex mantle flow below this localized volcanic province.  Active-source seismic refraction and multi-channel seismic (MCS) reflection data quantify cumulative extension accommodated by the border faults and intrarift faults. Border faults have throws up to ~8 km and bound half graben basins. Intrarift faults are also relatively large (throws up to 2.5 km) and active, and they are estimated to account for ~20-25% of cumulative upper crustal extension. Along-strike variations are observed in faulting and in crustal and lithospheric stretching. In this presentation, we will synthesize these seismic imaging results and compare them with complementary constraints, including from other parts of the SEGMeNT project .

 
Rise in the frequency and intensity of extreme temperature events over New Zealand in connection to synoptic circulation features
Authors: Thomas Anjali , McDonald Adrian , Renwick James , Tradowsky Jordis , Bodeker Greg
Published: March 2022

Extreme temperature events (ETEs) have evolved alongside the warming climate over most parts of the world. This study provides a statistical quantification of how human influences have increased the likelihood and frequencies of ETEs in New Zealand, depending on the synoptic weather type. We use the simulation under pre-industrial conditions (natural scenarios with no rise in greenhouse gases (GHGs)) and present-day conditions (anthropogenic scenarios) from the weather@home regional climate model. The ensembles of simulations under these two scenarios are used to identify how increases in GHG concentrations have impacted the frequency and intensity of ETEs based on their connection to different large-scale circulation patterns derived using Self Organizing Maps (SOMs). Over New Zealand, an average 2-3 fold rise in frequencies of extremes occurs irrespective of seasons due to elevated GHG concentrations with a mean temperature increase close to 1℃. For some synoptic situations, the frequency and intensity of ETEs are enhanced. In particular, for low-pressure centers to the northeast of New Zealand, the frequency of occurrence of daily temperature extremes has increased by a factor of 7 between anthropogenic and natural simulations for the winter season, though these synoptic patterns rarely occur. For low-pressure centers to the northwest of New Zealand, we observe extreme temperatures frequently in both anthropogenic and natural simulations which we attribute to warm air advection from the tropics. The frequency of occurrence of these synoptic patterns has also increased by a factor of 2 between the natural and anthropogenic simulations. For these synoptic states, the extremes are observed in the North Island and along the east coast of the country with the highest temperature along the Canterbury coast and Northland. However, the change between the natural and anthropogenic simulations is largest on the west coast along the Southern Alps.
Evaluation of satellite, gauge and reanalysis precipitation products over Aotearoa, New Zealand 
Authors: Vishwanathan Gokul , McDonald Adrian , Stone Dáithí , Rosier Suzanne , Rana Sapna , Noble Chris
Published: March 2022

Understanding precipitation variability is challenging, particularly in regions such as New Zealand, where the local topography strongly controls precipitation. This study provides a comprehensive evaluation of mean and extreme precipitation features over Aotearoa, New Zealand, using six merged satellite-gauge, five reanalysis, and three in-situ products, using station data as a reference. We find that all products show similar features in depicting the mean precipitation pattern with a clear maximum over the Alpine regions and a strong west-east gradient across the South Island. However, there are differences in the magnitude of mean precipitation estimates amongst different products at various regions on a seasonal timescale. Investigating the frequency of wet days shows that GPCP has the lowest count of all the satellite-based products, likely due to its coarse grid size, while MSWEP depicts the highest frequencies over the wettest region. Similarly, for reanalysis, MERRA-TP likely overestimates the frequency of occurrence west of the Alps compared to MERRA-PCORR, although the former showed better similarity with other datasets in terms of mean precipitation pattern. Moreover, statistical tests such as the Pearson correlation coefficient of the spatiotemporal pattern revealed that amongst the satellite-based products, MSWEP and GPM-IMERGE outperform other products with values of 0.9 and 0.66 with a mean wet-bias of 0.37 and 0.89 mm/day over the entire country. At the same time, ERA-5 and BARRA-R perform better in the suite of reanalysis products with a mean correlation coefficient of 0.87 and 0.74 with a mean wet-bias of 0.43 and 0.76 mm/day, respectively. This presentation also incorporates a set of precipitation indices approved by the ETCCDI committee to facilitate an intercomparison of different products in capturing the extreme tail of the distribution. Substantial differences especially over the West Coast in the South Island were observed in the interannual variability of the indices among different products. A closer examination of the percentile-based indices such as R95P and R99P revealed a contrasting pattern between different products in geographical regions. For instance, all the satellite-based products consistently showed wet bias as compared to the reanalysis products that depicted dry bias in all seasons. The MSWEP and BARRA-R datasets had the smallest relative percentage difference compared with the station data for most of the indices, suggesting their potential use for capturing both the mean and extremes characteristics of precipitation quite well in this region. 
Effects of inclusion of adjoint sea ice rheology on estimating ocean-sea ice state
Authors: Lyu Guokun , Zhou Meng
Published: March 2022

As part of the ongoing development of a data assimilation system for reconstructing the Arctic ocean-sea ice state, we incorporated an adjoint of sea ice rheology, which was approximated by free drift assumption due to stability problem, into an adjoint model of a coupled ocean-sea ice model. The adjoint sensitivity experiments show that the internal stress effect, represented by the adjoint rheology, induced remarkable differences in the sensitivities to ice drift and wind stress in the central Arctic Ocean. In contrast, ice is mostly free drift in the marginal ice zone. The assimilation experiments reveal that including the adjoint of ice rheology helps extract observational information, especially the ice drift observations, which improves the estimation of the sea ice decline process in 2012. The results suggested great potentials for further improving the Arctic ocean-ice state estimation in the framework of the adjoint method with the adjoint sea ice rheology included. 
Fractal density and local singularity analysis method for modeling extreme geological events 
Authors: Cheng Qiuming
Published: March 2022

The systematic study of extreme geological events (e.g., plate collision and subduction, earthquakes, volcanoes, and mineralization) that occurred during the evolution of the earth is essential not only for understanding the "abrupt changes in the evolution of the earth", but also for an in-depth understanding of the co-evolution of material-life-environment of the livable earth. However, due to the temporal and spatial anomalies and complexity of extreme geological events, classical mathematical models cannot be effectively applied to quantitively describe such events. Comparative studies of many types of geological events indicate that such extreme geological events often depict "singular" characteristics (abnormal accumulation of matter or massive release of energy in a small space or time interval). On this basis, the author proposes a unified definition of extreme geological events, a new concept of "fractal density" and a "local singularity analysis” method for quantitative description and modeling of extreme geological events. Applications of these methods to several types of extreme geological events have demonstrated that the singularity theory and methods developed in the current research can be used as general approaches for the characterization, simulation, and prediction of geological events. The case studies to be introduced include anomalous heat flow over the mid-ocean ridges, and major flare up magmatism and marine sediment flux fluctuations over the past 3 Ga history of earth continental crust evolution.
Linking soil microbial biodiversity to soil carbon dynamics
Authors: Khurana Swamini , Manzoni Stefano
Published: March 2022

Carbon emissions from soil are large contributors to the global carbon cycle, but depend on processes occurring at a small scale. Carbon cycling in the soils is mediated by plant roots, soil fauna, and microorganisms including fungi and bacteria. Sophisticated molecular analytical techniques have been developed to characterize soil microbial communities, resulting in discovery of new microbial species that are not yet culturable in the laboratory. The unculturable fraction of soil microbial communities make for a large data gap since we are not able to characterize their activity, and even less so their role in the microbial community. As a result, soil carbon models cannot be readily parameterized from the bottom up—essentially, we cannot quantify functions at low taxonomic level and then scale up to the community level. In this numerical study, we aim to explore how soil carbon model predictions are affected by microbial diversity as characterized in silico by distribution of traits.

The resilience of soil microbial communities is related to distance to the surface and diversity. Diverse microbial communities that are closer to the surface, experiencing regular temporal fluctuations in environmental conditions are more resilient to disturbances than microbial communities deeper down in the subsurface. However, forest management practices and extreme climate conditions impose conditions that may be hitherto unforeseen. This makes prediction of response of soil microbial communities to new disturbances and soil carbon respiration thereof to be uncertain. In this contribution, we developed a microbial process network incorporating diverse organic matter compounds, and bacterial and fungal species characterized by distributions of trait values (including co-variations and trade-offs). With this framework, we explore if soil microbial diversity is a good predictor for soil carbon stocks and study diversity effect on community-level responses to disturbance and variations in environmental conditions. These results will assist in the development of a rate expression to capture the contribution of soil microbial community composition to carbon dynamics in soil.
Regional-scale day-ahead wind power forecasting using deep learning
Authors: Lepetit Mathilde , Kurzrock Frederik , Aillaud Pierre , Sebastien Nicolas , Schmutz Nicolas
Published: March 2022

Historically, electricity was provided by dispatchable sources that are able to adjust to demand variations. Adding an irregular source to the network is a challenge for the grid stability. Especially, wind turbine production varies depending on meteorological conditions. At a regional or country scale, Transmission System Operators (TSOs) are responsible to maintain supply demand equilibrium in their network. In this context, wind power production forecast is one of the tools needed to manage the network. Traditionally, physical models are used to predict power production based on turbine characteristics and numerical weather prediction models. Indeed, wind power production is strongly correlated to wind speed at turbine hub height and other meteorological parameters. One limit of those physical approaches is that they require precise knowledge on turbines characteristics and locations, in particular at a regional scale.

To overpass this limit, a statistical approach such as deep learning can be used but needs to be qualified in terms of performances. In this study, a supervised deep learning model is explored. This model does not require information on turbine location or characteristics but does require historical samples of weather parameters and associated production.

Our work focuses on day-ahead forecasts (horizons 24 to 48 hours) for a German TSO (region-scale). One physical model was selected as a reference and the goal was to combine deep learning and physical predictions to obtain the best possible forecast. Both the physical and the deep learning models use spatiotemporal meteorological inputs from the IFS (ECMWF) and GFS (NCEP) models. A convolutional neural network (CNN) was used to exploit the spatial information of maps of features. A LSTM was added to capture information from the time series evolution. Finally, several deep learning predictions were combined with the physical model prediction using a multi-layer perceptron. With this method, the MAE-based skill score of our final model, combining the physical one and deep learning ones, reaches more than 6% over a validation period of one year.
MPG-S-NET: A multi-purpose low-cost GNSS collocation station network 
Authors: Aichinger-Rosenberger Matthias , Moeller Gregor , Hohensinn Roland , Rothacher Markus
Published: March 2022

Global Navigation Satellite System (GNSS) receivers are very versatile sensors, which have not only revolutionized positioning and navigation applications, but also provide numerous opportunities for environmental monitoring and remote sensing. Beside the monitoring of long-term ground movements and geodynamics, typical applications include the provision of water vapor estimates for numerical weather prediction (NWP) and climate studies as well as real-time applications such as seismic and geohazard monitoring. The rising number and quality of low-cost GNSS equipment, coupled with innovative telecommunication approaches (Internet of Things), allow for an increased and more cost-effective usage of such devices for those monitoring purposes, and thus foster a fast decision-making process.

An especially beneficial approach is the collocation of GNSS sensors at already existing meteorological or seismic stations. By using available infrastructure for power supply and communication, it can provide a sustainable and energy-effective extension of existing monitoring capabilities. The different parameters collected on-site can be used for cross-validation or provision of corrections for GNSS positioning. Furthermore, through (close to) real-time availability of observations, such collocated stations can aid early-warning systems for many different types of natural hazards (from extreme weather events to landslides and earthquakes). At the Institute of Geodesy and Photogrammetry at ETH Zürich we develop GNSS instrumentation to equip meteorological stations from the SwissMetNet (SMN). The work is carried out in the course of a pilot study in cooperation with MeteoSwiss.

This contribution introduces initial results of the SMN station Zürich-Affoltern, where the first prototype GNSS payload has been installed. We highlight key capabilities of the low-cost GNSS equipment used for these high-precision geomonitoring purposes. Moreover, we discuss concrete ideas for the build-up of a dedicated collocation network within the DACH (Germany-Austria-Switzerland) border area and the opportunities arising from it. These opportunities include the sustainable enhancement of infrastructure for climate change monitoring in the Alpine region as well as the build-up of early-warning systems for multiple types of geohazards. The latter might be achieved through the combination of parameters collected on-site with complementary data (e.g. satellite observations or NWP output) using innovative, data-driven approaches. Finally, we showcase examples and the potential of recent and ongoing works using these data-driven approaches.
Data-Driven MHD Simulations on Magnetic Flux Rope Eruptions
Authors: Guo Yang , Ding Mingde , Chen Pengfei , Xia Chun , Keppens Rony , Zhong Ze , Guo Jinhan , Ni Yiwei
Published: March 2022

Solar eruptions such as flares and coronal mass ejections could cause disastrous space weather. To understand and predict these eruptive activities, we have to combine multi-wavelength observations and numerical simulations. Recently, data-driven magnetohydrodynamic (MHD) simulations have provided a series of new findings in studying the accumulation of electric current and magnetic energy in active regions, in explaining magnetic flux rope eruptions and coronal mass ejections. We briefly review the progress in this field and introduce one way to realize data-driven MHD simulation, including processing magnetic field observational data, inversion of velocity field and electric field, models as initial conditions and subsequent dynamic simulations. Finally, we will look into the future of the data-driven simulations and point out several methods to improve the simulation results. 
Calibrating sediment thickness utilizing receiver functions and borehole data
Authors: Agrawal Shubham , Eakin Caroline , O'Donnell John
Published: March 2022

A blanket of sedimentary and regolith material covers approximately three-quarters of the Australian continent, obscuring the crustal geology below and potential mineral resources within. Sedimentary basins also trap seismic energy increasing seismic hazard and generating noisy seismograms that make determining deeper crustal and lithospheric structure more challenging. The most fundamental question that can first be asked in addressing these challenges is how thick are the sediments? Borehole drilling and active seismic experiments provide excellent constraints, but they are limited in geographical coverage due to their expense, especially when operating in remote areas. On the other hand, passive-seismic deployments are relatively low-cost and portable, providing a practical alternative for initial surveys. Here we utilize receiver functions obtained for both temporary and permanent seismic stations in South Australia, covering regions with a diverse sediment distribution. We present a straightforward method to determine the basement depth based on the arrival time of the P-converted-to-S phase generated at the boundary between the crustal basement and sedimentary strata above. Utilizing the available borehole data, we establish a simple predictive relationship between Ps arrival time and the basement depth, which could then be applied to other sedimentary basins with some consideration. The method is found to work best for Phanerozoic sediments and offers a way to determine the sediment-basement interface in unexplored areas requiring only temporary seismic stations deployed for < 6 months.

<img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gnp.fa7d61877ed167359691461/sdaolpUECMynit/22UGE&app=m&a=0&c=82b85d02d2969cb9185a9774fa7c48d1&ct=x&pn=gnp.elif&d=1" alt="" width="488" height="522">
Compare the Characteristics on Soil Temperature and Soil Moisture Between Two Tea Fields Managed by Different Strategies
Authors: Wang Siang-Heng , Juang Jehn-Yih
Published: March 2022

Management strategies in agricultural landscape plays a vital role to regulate soil moisture-atmosphere interaction. How farmer manage the canopy shading of their crop is a key factor to participate the interaction. The components that can be affected include soil temperature, soil water content and evapotranspiration. Soil temperature and water content sensors had been set in two neighboring tea fields in northern Taiwan that have their own management strategies by farmers, and eddy-covariance equipment also measure the evapotranspiration. Long-term ensemble average result showed that soil water content decreasing rate in organic-certified tea field is -1.23% Day-1, and conventional field is -0.76% Day-1. Among the decreasing rate has an obvious turn in four to five days after rainfall event. In addition, Diurnal difference of soil temperature between two fields in summer can reach 1.86 °C. Although organic tea field has milder diurnal soil temperature difference, but the dynamics of soil water content is higher than conventional field.
Increasing trend of Precipitable Water Vapor in Antarctica and Greenland
Authors: Ding Junsheng , Chen Junping , Tang Wenjie
Published: March 2022

Polar precipitable water vapor (PWV) is expected to increase under a warming climate. However, the conventional approach cannot provide sufficient long-term PWV records due to the high maintenance costs. Fortunately, the exponential explosion in the number of geodetic-quality Global Navigation Satellite System (GNSS) stations has broken this deadlock. Utilizing 20 radiosonde (RS) and 105 GNSS station data over two decades (1994-2020), we analyzed and evaluated the spatial and temporal variability characteristics of PWV in Antarctica and Greenland. The multi-year mean PWV values for Antarctica and Greenland were 5.63 ± 1.67 mms and 7.63 ± 1.35 mms, respectively, with annual standard deviations (STD) of PWV of 1.60 ± 0.77 mms and 3.44 ± 0.92 mms, respectively. In both Antarctica and Greenland, the PWV annual STD shows a gradual increase from the land center to the edge; while the PWV mean decreases with increasing latitude in Greenland, there is no significant latitudinal correlation in Antarctica. There is no significant regional difference in PWV trends, and from the statistical results, both Antarctica and Greenland show an increasing trend from year to year. The PWV trends in Antarctica and Greenland were 0.29 ± 0.77 mm/decade and 0.27 ± 0.64 mm/decade, respectively, with relative PWV trends of 5.98 ± 12.93%/decade and 3.87 ± 8.45%/decade, respectively.
Modeling seismic wave propagation in the earth using the distributional finite difference method
Authors: masson yder
Published: March 2022

We present the theory and applications of the Distributional Finite Difference Method (DFD). The DFD method is an efficient tool for modeling the propagation of elastic waves in heterogeneous media in the time domain. It decomposes the modeling domain into multiple elements that can have arbitrary sizes. When using large elements, the DFD algorithm resembles the finite difference method because the wavefield is updated using operations involving band diagonal matrices only. This makes the DFD method computationally efficient. When small elements are employed, the DFD method permits to mesh complicated structures as in the finite element or the spectral element methods. We present numerical examples showing that the proposed algorithm accurately accounts for free surfaces, solid-fluid interfaces and accommodates non-conformal meshes. Seismograms obtained using the proposed method are compared to those computed using analytical solutions and the spectral element method. The DFD method requires fewer points per wavelength (down to 3) than the spectral element method (5 points per wavelength) to achieve comparable accuracy. We present examples demonstrating the advantages of the DFD method for modeling wave propagation in the Earth at the global and regional scales. 
Multi-model-based evaluation of landslide susceptibility in a meizoseismal area
Authors: Wang Xiao , Wang Di , Li Shaoda
Published: March 2022

On August 8, 2017, a magnitude 7 earthquake struck Jiuzhaigou County, Aba Prefecture, Sichuan Province, inducing a large number of landslides. Evaluating the susceptibility to landslides induced by strong earthquakes can provide a scientific basis for disaster risk management and monitoring. However, different evaluation models can obtain different spatial distributions of landslide susceptibility, and thus, selecting the optimal model is the most effective way to improve the susceptibility evaluation. To select the most suitable evaluation model for a strong earthquake area (Jiuzhaigou), 12 influencing factors affecting the landslide occurrence, including slope, elevation, and aspect, were extracted, and different statistical analysis methods and machine learning models were used to calculate the susceptibility index. The results show that the deep neural network model had the highest accuracy (85.4%), followed by the random forest and support vector machine models (84.2% and 82.3%, respectively), while the logistic regression model and certainty factor models achieved accuracies of 80.8% and 76.2%, respectively. Accordingly, the deep neural network model can be considered a new tool to achieve the more accurate zonation of landslide susceptibility in meizoseismal regions.
Tropical peatland conservation in Indonesia as a nature-based solution
Authors: Deshmukh Chandra Shekhar , Susanto Ari , Asyhari Adibtya , Desai Ankur R. , Page Susan , Nardi Nardi , Nurholis Nurholis , Hendrizal Hendrizal M. , Kurnianto Sofyan , Suardiwerianto Yogi , Agus Fahmuddin , Astiani Dwi , Sabiham Supiandi , Gauci Vincent , Evans Chris
Published: March 2022

The importance of the land sector in addressing the climate and nature crises has gained worldwide attention. Nature-based solutions were a key topic at the recent United Nations Conference of the Parties (COP26) in Glasgow to limit global warming to well below 2 degrees. The conservation, restoration, and improved management of peatlands play a significant role in Indonesia's nature-based solutions.

The eddy covariance measurements of net ecosystem carbon dioxide and methane exchanges from a coastal peatland in Sumatra, Indonesia indicate that the GHG balance increased from 20.0 ± 4.5 tCO2e ha−1 yr−1 at the intact site (undrained and undisturbed forest cover) to 43.8 ± 1.5 tCO2e ha−1 yr−1 at the degraded site (drained with canal system and selectively logged). The significant carbon dioxide emissions from the intact site, during an extreme drought caused by a positive Indian Ocean Dipole phase combined with El Niño event, highlight the potential importance of climate regime in determining the GHG budget of tropical peatlands.

Although the measurements indicate that both intact and degraded peatlands in this study are warming the atmosphere, it remains clear that protection of the remaining intact tropical peatlands offers a viable way to avoid substantial GHG emissions from this globally important ecosystem, which for our study in Sumatra was 24 ± 5 tCO2e ha−1 yr−1. These results highlight that protecting all remaining intact peat swamp forests in Indonesia (6.2 Mha) from degradation will avoid GHG emissions of around 0.15 GtCO2e yr-1, this equates to ~10% of Indonesia’s GHG emissions in 2016.

Additionally, tropical peatland conservation contributes directly to the UN Sustainable Development Goals by fostering unique biodiversity and ecosystem services.
Fluid-driven earthquake sequences and aseismic slip in a poro-visco-elasto-plastic fluid-bearing fault structure
Authors: Dal Zilio Luca , Hegyi Betti , Behr Whitney , Gerya Taras
Published: March 2022

There is a growing interest in understanding how geologic faults respond to transient sources of fluid. However, the spatio-temporal evolution of sequences of seismic and aseismic slip in response to pore-fluid evolution is still poorly constrained. In this study, we present H-MEC (Hydro-Mechanical Earthquake Cycles), a newly-developed two-phase flow numerical code — which couples solid rock deformation and pervasive fluid flow — to simulate how crustal stress and fluid pressure evolve during the earthquake cycle on a fluid-bearing fault structure. This unified 2D numerical framework accounts for full inertial (wave) effects and fluid flow in a finite difference method and poro-visco-elasto-plastic compressible medium with rate-dependent strength. An adaptive time stepping allows the correct resolution of both long- and short-time scales, ranging from years to milliseconds during the dynamic propagation of dynamic rupture. We present a comprehensive plane strain strike-slip setup in which we test analytical benchmarks of pore-fluid pressure diffusion from an injection point. We then investigate how pore-fluid pressure evolution and solid–fluid compressibility control sequences of seismic and aseismic slip on a finite fault width. While the onset of fluid-driven shear cracks is controlled by localized collapse of pores and dynamic self-pressurization of fluids inside the undrained fault zone, subsequent dynamic ruptures are driven by solitary pulse-like fluid pressure wave propagating at seismic speed. Furthermore, shear strength weakening associated with rapid self-pressurization of pore-fluid can account for the slip–fracture energy scaling observed in large earthquakes. This numerical framework provides a viable tool to better understand fluid-driven dynamic ruptures — either as a natural process or induced by human activities — and highlight the importance of considering the realistic hydro-mechanical structure of faults to investigate sequences of seismic and aseismic slip.
Changes of channel bars in the wandering reach of the lower Yellow River from 2018 to 2021
Authors: Zhang Min
Published: March 2022

Since Xiaolangdi Reservoir began to retained sediment in 1999, the Lower Yellow River (LYR) has deepened and widened continuously. The bankfull discharge has increased obviously, and the average depth has increased 1.3m～3.3m. The incoming water was abundant in recent four years from 2018 to 2021, and the peak discharge in the four year were all greater than 4000m3/s. The maximum discharge of Xiaolangdi station has reached 5500m3/s, which is the largest one since 1996. The evolution of channel bar in wandering reach is always the focus in sediment-laden rivers, especially in erosion period. Therefore, to appraise the changes in wandering reach of LYR in the erosion period, this study presents a detailed investigation of the channel bar changes in recent typical floods form 2018 to 2021. We described the bar pattern formation and sensitivity in wandering reach of LYR. Furthermore, we analyzed the numbers and area of channel bars based on the remote sensing images. We convert the channel bar at the same level from the relationship between the area of channel bar and water level at low water period. The results show that the channel sinuosity has decreased from 1.25 to 1.22, while the radius of curvature has increased from 2.80 to 2.96km. The number and area of channel bar have increased slightly. This phenomenon was affected mainly by the operation of Xiaolangdi Reservoir. The clear water and few bankfull discharge in 21 years since 1999, the channel erosion efficiency has decreased in the first ten years. So the erosion in recent four years floods was fewer. And the changes of channel bar slightly in recent four years. But the channel bar and channel pattern evolution dramatically from 1999 to 2021. 
Piloting novel multi-centennial palaeoclimate records from mainland southeast Australia.
Authors: O'Connor Jacinda , Henley Benjamin , Brookhouse Matthew , Allen Kathryn
Published: March 2022

High-resolution palaeoclimate proxies are fundamental to our understanding of the diverse climatic history of the Australian mainland, particularly given the deficiency in instrumental datasets spanning greater than a century. Annually resolved, tree-ring based proxies play a unique role in addressing limitations in our knowledge of interannual to multi-decadal temperature and hydroclimatic variability prior to the instrumental period. Here we present cross-dated ring-width (RW) and minimum blue-intensity (BI) chronologies spanning 70 years (1929 – 1998) for Podocarpus lawrencei Hook.f., the Australian mainland's only alpine conifer, based on nine full-disk cross-sections from Mount Loch in the Victorian Alps. Correlations with climate variables from observation stations and gridded data reveal a significant positive relationship between RW and mean monthly maximum temperatures in winter throughout central Victoria (r = 0.62, p < 0.001), and a significant negative correlation to winter precipitation (r = -0.51, p < 0.001). We also found significant negative correlations between RW and monthly snow depth data from Spencer Creek in New South Wales (r = -0.60, p < 0.001). Of the assessed BI parameters, delta blue-intensity (ΔBI; the difference between early- and late-wood BI) displayed the greatest sensitivity to climate, with robust spatial correlations with mean October to December maximum and minimum monthly temperatures (r = -0.43, p < 0.001; r = -0.51, p < 0.001) and July precipitation (r = 0.44, p < 0.001), across large areas of northern Victoria. These promising findings highlight the utility of this species for future work. With the very limited availability of suitable long-lived and cross-datable species on the Australian mainland, these results have implications for the significant advancement of palaeoclimate records in southeastern Australia and the potential for improvement in our understanding of past climate in the region.
Evapotranspiration frequently increases during droughts
Authors: Zhao Meng , Aa Geruo , Liu Yanlan , Konings Alexandra
Published: March 2022

During droughts, low water availabilities limit soil evaporation and induce stomatal closure to prevent transpiration, leading to reductions in evapotranspiration (ET). At the same time, drought-associated meteorological conditions such as high temperature elevate atmospheric evaporative demand, acting to increase ET. However, the overall effect of drought on the sign of ET anomalies remains unknown, as are the determinants of this response. Positive anomalies during drought (ET+), in particular, are of concern because they quickly deplete water resources, may cause flash droughts, and exacerbate ecosystem stress. Because remotely sensed ET datasets implicitly assume a stomatal response to drought, they cannot provide direct observational constraints of the prevalence of ET+. Eddy covariance tower records are often too short and sparse to adequately sample drought conditions. To avoid these shortcomings, we used a water balance approach to derive a new estimate of ET+ occurrence during droughts by combining total terrestrial water storage (TWS) observations from the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) with Global Precipitation Climatology Project precipitation data. The robustness of this approach is demonstrated across 104 hydrological basins. With this new water balance-based estimate, we showed that ET+ during droughts are globally widespread. On average, ET+ occurs in ~45% of drought periods, and it is more likely to occur during milder droughts (with relatively lower P reductions and ample available TWS). CMIP6 Earth system models (ESMs) underestimate the observed ET+ probability by nearly half. This underestimation is particularly large in relatively dry locations with an aridity index (P/PET) below ~1.5 and can be attributed in part to an overly strong ET response to decreases in soil moisture in these regions. Furthermore, ESM’s lack of accounting for variability in plant water stress response traits within plant functional types exacerbates their underestimation of ET+. This demonstrates for the first time that local adaptation of plant water stress response traits reduces the impact of droughts on ET. These process representations should be improved to reduce model uncertainties in predicting drought impacts on the energy-water-carbon nexus.
The invention of partitioning well pipe to observe solute transport in aquifers: Laboratory sandbox and synthetic studies 
Authors: Lee Bu-Sheng , Li Jian-Dao , Lin Hong-Ru , Wen Jet-Chau
Published: March 2022

According to previous studies, the spatial distribution accuracy of hydrogeological parameters will directly affect the geological assessment and prediction of solute transport in aquifers. In order to describe the heterogeneity of aquifers, Hydraulic conductivity (K) and the specific storage coefficient (Ss) are among the essential hydrogeological parameters as the traditional sampling method consumes construction cost and time. Therefore, the purpose of this study is to design a multi-stage concentric well pipe, which can measure the water level at different depths in a single well pipe. To thoroughly evaluate the delicate characteristics of heterogeneous aquifers, a three-dimensional (3-D) sandbox model will be used to simulate the real underground environment for pumping experiments, and the distribution field of hydrogeological parameters will be estimated by hydraulic tomography (HT). Finally, simulation of the pollution flow direction at the heterogeneous underground field is constructed by VSAFT3. Our study highlights the importance of analyzing the characteristics of groundwater geology parameters by vertical and horizontal. And through the numerical simulation and the real field fitting of the sand box. It is proved that the partitioning well pipe can accurately estimate the 3-D field of hydrogeological parameters and can effectively predict solute transport. This research will significantly contribute to the future analysis of changes in regional flow fields, groundwater replenishment patterns, and control of the diffusion of underground pollution.
Fosferrox: A biogeochemical model extension for coupled iron, phosphorus and sulphur dynamics in response to changes in bottom water oxygen in BALTSEM
Authors: Hermans Martijn , Gustafsson Erik , Gustafsson Bo G , Slomp Caroline P , Jilbert Tom
Published: March 2022

Marginal marine systems, such as the Baltic Sea, are naturally susceptible to bottom water oxygen (O2) depletion due to strong stratification and restricted horizontal water exchange. In recent decades, bottom water hypoxia (O2 < 63 μM) and anoxia (O2 = 0 μM) have been further exacerbated in coastal areas due to excessive anthropogenic nitrogen (N) and phosphorus (P) inputs. Feedback mechanisms in the coupled biogeochemical cycling of P, iron (Fe) and sulphur (S) play a major role in controlling bottom water O2 conditions. Phosphorus release from the seafloor amplifies when bottom water O2 availability is low due to reductive dissolution of iron (Fe) oxide-bound P and preferential P regeneration from organic matter. This Fe oxide-bound P feedback mechanism has been suggested to play a key role in the rapid transitions at the onset and end of multidecadal hypoxic events in the Baltic Sea. Currently, the coupled biogeochemical cycling of Fe, P and S is not explicitly described in Baltic Sea models. For example, BALTSEM, the principal model used in decision making under the Baltic Sea Action Plan, does not include a representation of coupled Fe, P and S cycling and therefore utilises simplified parameterisations to mimic feedback mechanisms. A critical deficiency is that such parameterisations are calibrated for present-day state only, and do not take into account large-scale changes in the spatial distribution of Fe, P and S over long time-scales. Therefore, it can become difficult to predict possible future changes or to reproduce past events. Here, we introduce a new model extension for BALTSEM, so-called Fosferrox, that simulates the coupled dynamics between Fe, P and S in response to changes in bottom water oxygen for present day (1850-2100 A.D.). The implementation of such a mechanistic coupled biogeochemical cycling between Fe, P and S, and its associated feedback mechanisms in Baltic Sea models is fundamental to better understand how changes in, for example, P loading might impact water column redox conditions, as well as to improve hypoxia abatement strategies. The main impetus is to extend the functionality of Fosferrox to gain a better mechanistic understanding of how the coupled Fe, P and S feedback mechanisms drive the multidecadal oscillations in Baltic Sea hypoxia.
Flow Resistance Due to Rigid and Flexible Vegetation: A Review
Authors: Rathod Laxman V , Timbadiya Prafulkumar V , Barman Bandita
Published: March 2022

Riverbank and floodplain vegetation substantially affects the fluvial processes and play a key role in river hydraulics and river management. Presence of vegetation influences the water levels, flow velocity profiles and resistance to flow. Therefore, better understanding of behavior of flow over vegetation is required in design of vegetative channels, construction of stage-discharge curves, determining horizontal flow structure around hydraulic structures, and to develop numerical models. A detailed review of flow resistance due to rigid and flexible vegetation has been done under both emergent and submerged conditions. Based on the flow conditions and vegetation features, the investigators made a transition between rigid, flexible, emergent, and submerged vegetation. The variation of the flow field in the vegetative open channel follows a two-layer approach, it is almost constant inside the vegetation layer and logarithmic one above the vegetation layer. Firstly, several theoretical approaches for determining the resistance due to rigid vegetation in emergent and submerged condition are discussed. For simplicity many investigators have considered a rigid cylinder without side branches and foliage, the vegetation having constant height, stem diameter, and uniform flow condition was considered as rigid. The resistance due to vegetation also depends on the uniform and staggered pattern arrangements, the latter has more impact on flow in comparison to the former. The analysis for flexible vegetation is complex due to the complex nature of vegetation, and it is difficult to take the heterogenous nature of field vegetation into the account. The resistance due to flexible vegetation is a function of the height of vegetation, vegetation density, foliage, plant form alignment of vegetation, submergence ratio, and type of vegetation. The flexible vegetation also assumes different configurations depending on the hydrodynamics of flow and bending stiffness. Furthermore, more recent approaches for describing the resistance due to flexible vegetation are presented.

Keywords: Rigid vegetation, Flexible vegetation, Resistance to flow, Rivers, Floodplains, Flow field
Aseismic slip and cascade triggering process of foreshocks leading to the 2021 Mw 6.1 Yangbi Earthquake
Authors: Liu Xiao Ge , Xu Wen Bin , He Zi Long , Fang Li Hua , Chen Zhi Dan
Published: March 2022

Understanding the nature of foreshock evolution is important for earthquake nucleation and hazard evaluation. Aseismic slip and cascade triggering processes are considered to be two end-member precursors in earthquake nucleation processes. However, to perceive the physical mechanisms of these precursors leading to the occurrence of large events is challenging. In this study, the relocated 2021 Yangbi earthquake sequences are observed to be aligned along the NW-SE direction and exhibit several evident spatial migration fronts towards the hypocenters of large events including the mainshock. An apparent static Coulomb stress increase on the mainshock hypocenter was detected, owing to the precursors. This suggests that the foreshocks are manifestations of aseismic transients that promote the cascade triggering of both the foreshocks and the eventual mainshock. The temporal depth of the brittle-ductile transition exhibit deepening, followed by shallowing during the foreshock-mainshock-aftershock sequence. By jointly inverting both InSAR and GNSS data, we observe that the mainshock ruptured on a blind vertical fault with a peak slip of 0.8 m. Our results demonstrate that the lateral crustal extrusion and lower crustal flow are probably the major driving  mechanisms of mainshock. Additionally, the potential seismic hazards on the Weixi-Weishan and Red River faults deserve further attention
Influence of Dust on Climate during the late Palaeozoic ice age
Authors: Lin Qifan , Liu Yonggang
Published: March 2022

Dust in the atmosphere affects climate by directly absorbing and scattering solar radiation. In present days, most of dust is emitted from dry regions over North Africa and Arabian Peninsula. It has been shown that it impact on global mean surface temperature, African monsoon, the number of tropical cyclones over the Atlantic Ocean, ENSO variability and the strength of Atlantic meridional ocean circulation (AMOC). The climate of late Paleozoic ice age bears some similarity to late Cenozoic climate. However, late Paleozoic ice age was a period of continental convergence and supercontinents formation. On different continental configurations, the area of dry regions may vary considerably, so that dust emissions and atmospheric dust loading changed accordingly. As  expected, the impact of dust on climate during this period was also very different from that of present days. In this work, we use the fully coupled global climate model CESM1.2.2 to examine the influence of dust on climate during late Palaeozoic ice age. Dust aerosols simulated by bulk aerosol model alter atmospheric radiation through scattering and absorbing both shortwave and longwave radiation. Results show that during late Palaeozoic ice age, sources of dust were mainly distributed on the western continent in the subtropics. The total amount of the atmospheric dust loading was less than that of present days due to the smaller subtropical continental area. Such dust induced a significant cooling of surface temperature at low latitudes by altering radiation. Dust falling on southern hemisphere continents covered by ice and snow caused a rising of surface temperature.
Exploiting multi-point in situ measurements during the Comet Interceptor comet flyby
Authors: De Keyser Johan , Henri Pierre , Simon-Wedlund Cyril
Published: March 2022

The ability to conduct multi-point measurements is a hallmark of the ESA-JAXA/Comet Interceptor mission currently in development. The mission consists of one spacecraft (A) and two probes (B1 and B2) which are expected to fly by a medium- to high-activity comet at a high relative speed (up to 70 km/s). The payload on spacecraft A and on probes B1/B2 provides different opportunities to perform multi-point in-situ data exploitation. We discuss how information about radial, solar zenith angle and latitudinal variations can be extracted from the measurements, for instance using multi-point data analysis techniques inherited from the ESA/Cluster mission. We consider different spacecraft configurations and different geometries for the spacecraft trajectory relative to the comet, as well as target comets with gas production rates between those of 67P/Churyumov-Gerasimenko and 1P/Halley. We highlight the various opportunities and limitations of the proposed algorithms. Particular attention is given to the need for data that are well intercalibrated and discuss what can be done if the intercalibration is not perfect.