bluuebunny/crossref_metadata_2025 huggingface dataset:
Amazonas Rainfall Modifying Gas Concentration and Forming Nucleation Particles Near the Surface
Authors: Machado Luiz A. T. , Pöhlker Christopher , Harder Hartwig , Andreae Meinrat O. , Artaxo Paulo , Botia Santiago , Cheng Yafang , Franco Marco A. , Kremper Leslie , Komiya Shujiro , Lavric Jost , Leliveld Jos , Hang Su , Quesada C. Alberto , Pöhlker Mira , Trumbore Susan , Walter David , Williams Jonathan , Wolff Stefan , Pöschl Ulrich
Published: March 2022

This study combines ground-based gas phase, particle, and rainfall measurements at the ATTO site to study the impact of rainfall events on greenhouse and reactive gas concentrations and discuss how this process is relevant for producing new particles. Measurements of CO2, CH4, CO, O3, NO, and NO2 concentrations were collected from the surface to 79m using a tower at the ATTO site in the central Amazon forest northeast of Manaus, Brazil. Particle size distribution was measured by an SMPS and rainfall by a rain gauge at the top of the tower. Data collection started in 2012, and this analysis covered the period up to 2020. The 30-minute interval dataset was used to study how convective events modify the concentration of these gases. During the rainfall events, CO2, CO, and CH4 concentrations decrease, though CH4 varies less with height than CO and CO2. The daily cycle of NO2 presents an interesting characteristic showing distinct daily evolution for the concentration in the upper and lower levels. The decrease in NO2 concentration in the upper level and the increase near the surface in the afternoon, which is the typical time of rainfall events, indicate that a specific process occurs near the surface. With the joint analysis of gas-phase observations with ultrafine particles and rainfall data, it was possible to evaluate the interesting physical-chemical processes occurring during the rainfall events that might be important for particles nucleation. The time of rainfall events was defined as the first-time rain rate reaching 3 mm/hours, a typical value of the beginning of convective rainfall events. Interestingly, during rainfall events, there is a significant injection of O3 above and inside the canopy, and at this moment, its concentrations can increase by 300%. At the same time, NO decreases, and NO2 increases its concentration, suggesting a reaction between NO and O3 forming NO2. The concentration of NO2 follows the increase in particle concentration smaller than 20nm. This result opens new perspectives on the role of new particle formation related to rain and vertical mixing in the Amazon.
The use of low-cost sensors for monitoring coastal climate hazards and developing early warning support against extreme events. 
Authors: Ahmed Tasneem , Creedon Leo , Anton Iulia , Gharbia Salem
Published: March 2022

Coastal areas are socially, economically, and environmentally intensive zones. Their risk to various natural coastal hazards like coastal flooding, erosion, and storm surges has increased due to climate-induced changes in their forcing agents or hazard drivers (e.g. sea-level rise). The increased exposure (e.g. dense population living near the coast) and vulnerability (e.g. insufficient adaptation) to these hazards in the coastal areas have complicated the adaptation challenges.

Thus, monitoring coastal hazards is essential to inform suitable adaptation to increase the climate resilience of the coastal areas. In monitoring coastal climate hazards to develop coastal climate resilience, both the forcing agents and the coastal responses should be observed.

As coastal monitoring is often expensive and challenging, creating a database through a systematic analysis of low-cost sensing technologies, like UAV photogrammetry for monitoring the hazards and their drivers would be beneficial to the stakeholders. Real-time information from these low-cost sensors in complement to the existing institutional sensors will facilitate better adaptation policies including the development of early warning support for building coastal resilience. In addition, it would also provide a valuable dataset for validating coastal numerical models and providing insights into the relationship between these hazards and forcing agents. Additionally, such low-cost sensors would also create opportunities for engaging citizens in the data collection process, for efficient data collection, and increasing scientific literacy amongst the general public. For instance, in the Sensing Storm Surge Project (SSSP), citizen science was used to collect technical data to characterise estuarine storm surges, generating data useable in peer-reviewed Oceanography journals. Coastal areas show complex morphological changes in response to the forcing agents over a wide range of temporal and spatial scales. Thus, monitoring the hazards with a sufficient temporal and spatial resolution is imperative to distinguish the changes in these hazards/drivers due to climate change from natural variability. This will not only help address the response strategies to these hazards but also adjust these response strategies according to the changing vulnerability of a particular region.

The database of the low-lost sensors thus created is in no way exhaustive since those have been retrieved through a certain combination of keywords in databases like Sciencedirect, Web of Science, and Scopus, nonetheless it is useful as these are the latest low-cost sensors available to monitor the major coastal hazards in the vulnerable coastal regions.
The Geoheritage value of the iconic buildings of Iaşi City, Romania
Authors: Anastasiei Ana-Maria , Niacşu Lilian , Enea Andrei
Published: March 2022

Iconic buildings in Iași City are an expression of the local geologic and geomorphologic settings, because building materials are locally procured. We analyse and highlight the reasons why this particular city – characterised by many emblematic buildings and a high potential in terms of building materials, may successfully develop its geotourism sector. A case study of the geotourism enhancement of the Repedea site as a source of construction and ornamental stone for some iconic buildings in Iasi City is presented. We want to argument that geotourism in Iasi city can be integrated as part of urban tourism. Its traditional sense, namely as the kind of tourism specific to such landscapes, should be understood as a catalyst of urban architecture and building materials. These explicitly reflects the local geomorphological and geological environment, thus being an important element of the trips that aim to offer the experience of a special place in the city.
Geochemistry of modern weathering and bole beds of the Deccan Traps, India
Authors: Patel Anuradha , Tripathi Jayant , Raj Rachna
Published: March 2022

Basalt is the most weatherable rock with its importance in sequestering atmospheric CO2. The Deccan basalts cover almost 15% of the geographical area of India. This study investigates the processes of chemical weathering operating in the modern basalt weathering profile and intertrappean beds in and around the district of Indore, Madhya Pradesh, India. There have been reports that the bole beds may have originated by aeolian deposition. The geochemical data was used to calculate the chemical index of alteration (CIA) and geochemical mass balance values (Ʈ). Weathered profiles have been studied for REE behaviour. The bole beds show a very high chemical index of weathering. The elemental mobility does not show any regular pattern. However, the REE patterns show slight depletion or enrichment, with stronger Ce mobility in some horizons. The geochemical study suggests that the highly weathered bole beds have originated from the chemical weathering of the surrounding basaltic rocks, not from the other external materials.
Testing the Strain-rate Hypothesis for Deep Slab Seismicity
Authors: Billen Magali , Fildes Rebecca , Thielmann Marcel , Fraters Menno
Published: March 2022

The occurrence of deep earthquakes within subducting lithosphere (slabs) remains enigmatic because these earthquakes have many similarities to shallow earthquakes, yet frictional failure is strongly inhibited at high pressure. Regardless of depth, earthquakes occur where the temperature is cold enough that elastic deformation is accumulated over time: for frictionally controlled earthquakes at shallow depth, the rate of seismic moment release is correlated with the strain-rate. Comparison of spatial variation in strain-rate magnitude from 2D simulations of subduction to observed seismicity versus depth profiles suggest that strain-rate may also be a determining factor in the occurrence of deep slab seismicity (1). In addition, proposed mechanisms for deep earthquakes, including transformational faulting of metastable olivine and thermal shear instability, are known to depend directly on strain-rate. To test the hypothesis that strain-rate is a determining factor in the spatial distribution of deep earthquakes, we are creating 2D models of subduction with visco-elasto-plastic (VEP) rheology and a free surface in the software ASPECT (2). The 2D slab structure is constructed for specific locations in which the slab geometry is extracted from Slab 2.0 (3) and the plate age and convergence rate are used to define the thermal structure using a new mass-conserving slab temperature model (4) implemented in the Geodynamic WorldBuilder (5). The resulting strain-rate and stress, together with the pressure and temperature along multiple transects of the slab are used as input values for a 1D thermal shear instability model (6) using the same VEP rheology as the slab deformation models.  Using this approach we can test whether the conditions in the slab favor failure through thermal shear instability and compare the spatial distibution to obsered seismicity. Initial results of this workflow will be presented, including how we have overcome some of the challenges in running VEP models for comparison to present-day slab seismicity. References: 1. Billen, M. I. , Sci. Advances, 2020. 2. Bangerth, W. et al., https://doi.org/10.5281/ZENODO.5131909, 2021. 3. Hayes, G.P. et al., Science, 2018. 4. Billen, M. I. and Fraters, M. R. T., EGU Abstract, 2022. 5. Fraters, M. R. T. et al., Solid earth, 2019. 6. Thielmann, M. Tectonophysics, 2018. 

 
Oriented crystal attachment in granites
Authors: Gordon Charlotte , Wallis David
Published: March 2022

Many fundamental questions about the nature of granitic magmas remain unresolved. Two important topics of recent debate are:

1) Do granite textures faithfully record magmatic processes, or are they mainly dictated by near- or sub-solidus processes?

2) Are granitic magmas fluid enough to allow phenomena such as crystal settling and turbulence, or so viscous that such processes are impossible and the magmas are confined to laminar flow?

We present new microstructural data from K-feldspar megacrysts and their inclusions that are pertinent to both of these questions.

K-feldspar megacrysts are common in granitic rocks and their formation has been variously ascribed to melt-rich, melt-poor or solid-state processes. The megacrysts frequently contain systematically arranged mineral inclusions, particularly of plagioclase, but also of amphibole, quartz, biotite and titanite. We studied samples from porphyritic granodiorite units in the Tuolumne Intrusive Complex, to ascertain how the crystals came to be included in the K-feldspar megacrysts.

We performed CL and EBSD analyses of the plagioclase inclusions. CL imaging reveals that many of the inclusions feature complete, symmetrical, concentric zoning, indicating that they grew freely in melt before becoming included. EBSD analysis demonstrates that the inclusions’ orientations are strongly controlled by the faces of both the plagioclase and the K-feldspar. Within the constraints imposed by faces, there is an additional crystallographic control, with some orientations more common than others.

Taken together, these findings strongly indicate the process of synneusis, whereby crystals drift together in melt and attach to each other, often on their largest faces and in certain low-energy orientations. This process occurs in melt-rich environments and its preservation in K-feldspars indicates that these textures could not have formed near or below the solidus. Synneusis also requires the relative motion of crystals through the melt (for example, due to crystal settling or magma turbulence), so its occurrence implies that the granitic magma was, at least episodically, fluid enough to allow widespread relative motion and rotation of its crystals.
Implementation of the Zoet-Iverson basal sliding law in CISM
Authors: van den Akker Tim , Lipscomb William H. , Leguy Gunter R. , van de Berg Willem Jan , van de Wal Roderik S.W.
Published: March 2022

There are large uncertainties in model predictions of the Antarctic Ice Sheet (AIS) contribution to future sea level rise. One source of model uncertainty is the description of basal friction. Here, we implement a new basal sliding law, developed by Zoet and Iverson (2020), in an updated version of the Community Ice Sheet Model (CISM). The Zoet-Iverson sliding law combines properties of two previously used sliding laws: power-law behavior in areas with slow-moving ice and coulomb-law behavior in fast-moving ice streams and outlet glaciers. We adress the behavior and performance of the Zoet-Iverson law in CISM using AIS spin-up procedures developed for the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6). We invert a non-dimensional coefficient in the Zoet-Iverson law to match modelled and observed thickness for grounded ice. Ocean temperatures are tuned to nudge ice-shelf thickness via the basal melt rates. These tuning processes are Antarctic-wide, but we focus on the Amundsen Sea region. We then advance the model forward to better represent the present-day Thwaites glacier, by inverting for observed ice velocity and by changing the ocean forcing. The main results from this run are the sub-shelf ocean temperature perturbation, thickness, and velocity profile of Thwaites glacier. Results are compared with different sliding laws to demonstrate the effect of the Zoet-Iverson law on the representation of the ongoing retreat. 

Zoet, L.K. & Iverson, N.R. (2020). A slip law for glaciers on deformable beds. In: Science 368 (6486), pages 76-78. DOI: 10.1126/science.aaz1183
Holocene silt-clay overbank sedimentation between climate change and human activitiy within the fragile loess-covered Weiße Elster catchment in Central Germany
Authors: von Suchodoletz Hans , Fütterer Pierre , Zielhofer Christoph , Veit Ulrich , Ettel Peter , Werther Lukas , Stäuble Harald , Tinapp Christian , Schneider Birgit , Sprafke Tobias , Werban Ulrike , Ballasus Helen , Miera Jan
Published: March 2022

The role of climatic or human forcing for Holocene silt-clay overbank sedimentation in Central Europe has been debated for decades. To date, former studies were often limited by rather low chronological resolutions of the fluvial stratigraphies, and especially by records of human activity in the studied catchments with rather fragmentary spatial and chronological resolutions.

Within the frame of an interdisciplinary geoarchaeological project carried out in the Weiße Elster catchment in Central Germany, using drill cores, geophysical measurements, sedimentological and micromorphological analyses as well as numerical dating along three transects, we build up a highly resolved record of fine-grained fluvial sedimentation along the middle river reach. Complementarily, based on archaeological data stored in local area files of the State Offices of Archaeology as well as on historical and onomastic data, we build up a catchment-wide record of human activity from the Early Neolithic period until the High Middle Ages with a so far unprecedented high spatial and chronological resolution in Central Europe. Comparing these geomorphologic and archeological/historic datasets with highly resolved paleoclimatic records allows a large step forward in understanding the intricate interplay of the Holocene geomorphodynamics with climate changes and human activity with an exceptional spatial and chronological resolution. So far, first results demonstrate a significant impact of climatic events such as the Little Ice Age on river activity that were linked with fine-grained sedimentation also after the start of intensive human activity in the catchment since the Early Neolithic period ca. 7.5 ka.
Chronology and sedimentary characteristics of rock avalanches from Meseta Belgrano to Lago Pueyrredón Valley, Patagonia
Authors: Kapustová Veronika , Pánek Tomáš , Břežný Michal , Schönfeldt Elisabeth , Winocur Diego , Smedley Rachel
Published: March 2022

On the northern slopes of Meseta Belgrano (MB), eastern foothills of Patagonian Andes in Argentina, complex of multiple overlapping rock avalanches and landslides can be found. Interpretation of remote-sensing data, field mapping, together with OSL dating of lacustrine sediments revealed that slope collapses evolved during last oscillations of the Patagonian Ice Sheet and after its retreat. The longest rock avalanche with ~11 km runout originated most likely before the last glacial advance following the LGM because it involves moraine deposits in part of the scarp area. We suppose, that the distal part of the rock avalanche body was subaqueous due to presence of a proglacial lake in Lago Pueyrredón Valley after LGM. The hummocky character of the distal body and its lithological composition coming from MB bedrock was preserved, but the deposit is discontinuous with straight east-west glacial lineations on the surface. We think this is result of erosion by the ice sheet approaching from East during post-LGM glacial fluctuations. Next pronounced landslide activity took place after ~17 ka BP, when at least three rock avalanches overlaid lacustrine sediments in a dropping proglacial lake. One of them, superimposing the above described older rock avalanche, evolved from the collapsed moraine deposit and created ~5 km long lobe with subaqueous radial distal part. In the proximal parts of the rock avalanches east from this form, bellow the slopes of MB, distinct large ridge-like forms are visible in topography. They are similar to moraine ridges preserved on the MB slopes in higher altitudes. They can be interpreted as lower-lying moraines, but this requires another pronounced ice-sheet oscillation after its final retreat, which was not documented in Patagonian Ice Sheet chronostratigraphy. Thus, we interpret them as Toreva blocks. Documentation and granulometric analysis of natural outcrops in rock avalanche bodies show that typical features, i.e. blocky, jigsaw and fragmented facies are present throughout the depth along whole travel distances of rock avalanches. Fragmented facies with jigsaw-fractured blocks and preserved original lithology sequence are most frequent. Sedimentary facies are very similar in all of the studied rock avalanches, which collapsed from bedrock MB slopes, regardless of their age or size.
In situ calibration of soil-plant-atmosphere simulations, for precision irrigation practice, using timeseries of crop’s vigor and water state
Authors: Casadesus Jaume , Bellvert Joaquim
Published: March 2022

In precision irrigation, a wise approach for decision making would consider not only a response to the current observations by sensors or other means. It should also consider forecasting the near future and prospecting hypothetical scenarios for water requirements and potential yield. These would require simulations which, in turn, demand for site specific characterization of the Soil-Plant-Atmosphere scenario. While crop parameters can be retrieved relatively easy from remote sensing, the availability of precise soil data would be limiting the accuracy of the simulations. Such limitations could be alleviated by in-situ calibration of the soil-crop models where the simulated soil water budget is contrasted with observed series of crop’s vigor and water state. This contribution describes an example where the soil waterholding capacity was estimated from inverse modelling during the seasons of 2020 and 2021 in a vineyard near Lleida, Spain.
Using GRACE Satellites to Estimate Impacts of Climate and Irrigation on Water Storage Changes in Major U.S. Aquifers
Authors: Scanlon Bridget , Rateb Ashraf , Sun Alexander
Published: March 2022

Managing water resources sustainably requires a comprehensive understanding of the effects of climate extremes (floods and droughts) and human water use (particularly irrigation) on water storage. In this study we examined the relative importance of climate and human drivers on variability in total water storage (TWS) from GRACE satellites compared with drought indices and irrigation water use in 14 major aquifers within the U.S. Results show marked depletion of TWS, tracked by GRACE satellites, was restricted to the semi-arid southwestern Central Valley and south-central High Plains, totaling ~90 km3, ~3× greater than the capacity of Lake Mead, the largest U.S. reservoir. Water storage depletion in the Central Valley was linked to long-term droughts (≤5 years) that were amplified by changing water sources from predominantly surface water irrigation during wet periods to groundwater irrigation during droughts. Interannual variability in TWS dominates long-term variability in major aquifers throughout the rest of the U.S. In the eastern U.S., aquifers in humid regions show low TWS trends related to low drought intensity. Although groundwater pumpage for irrigation in the humid Mississippi Embayment aquifer exceeded that in the semi-arid California Central Valley, no TWS depletion was recorded in the GRACE satellites in the Mississippi Embayment aquifer. The lack of TWS depletion is attributed to groundwater pumpage capturing streamflow in this humid region. Low or slightly rising trends in TWS in the northwest U.S., Columbia and Snake River Basins are attributed to surface water irrigation dampening drought impacts and disconnecting storage from climate forcing. The analysis of GRACE data shows synergies between climate and irrigation, with amplified water storage depletion in the semi-arid southwest and southcentral U.S., little impact on water storage in the humid east, and dampened water storage depletion in the northwest and north central U.S. To enhance the sustainability of water resources, groundwater and surface water should be used conjunctively, with inefficient surface water irrigation increasing groundwater recharge and efficient groundwater irrigation minimizing storage depletion. The use of managed aquifer recharge has been expanding within the past decade in different aquifers. Results of this study have important implications for managing water resources more sustainability within the context of climate extremes and intense irrigation globally.
Quiet Time Suprathermals Across Solar Cycle 23 & 24: Abundances and Spectral Indices
Authors: Alterman Benjamin L. , Desai Mihir I. , Dayeh Maher , Mason Glen M. , Ho George
Published: March 2022

We report on the annual variation of quiet-time suprathermal ion composition and spectral properties for C-Fe using Advanced Composition Explorer (ACE)/Ultra-Low Energy Isotope Spectrometer (ULEIS) data over the energy range 0.3 MeV/nuc to 1.28 MeV/nuc from 1998 through 2019. We show that (1) the number of quiet-time hours strongly anti-correlates with the annual Sunspot Number (SSN) at the -0.95 level; (2) a clear ordering of the cross correlation between abundance (normalized to O) and SSN as a function of solar wind mass-per-charge M/Q; (3) the slope of X/O abundance as a function of Fe/C decreases with increasing M/Q; and (4) annual spectral indices γ = 2.5 independent of solar activity and M/Q. We also discuss the trend of annual spectral indices with respect to Oxygen’s spectral index as a function of solar cycle and M/Q. Using our quiet time selection methods, we show that our results are robust against our quiet time selection criterion.
An improved jet-relative coordinate system for the detection of tropopause folds
Authors: Rivoire Louis , Linz Marianna , Curbelo Jezabel , Golja Colleen
Published: March 2022

Tropopause folds are documented to be frequent occurrences in the vicinity of the polar and subtropical jets. The rapidly changing nature of the folds and their complex fine scale structure make quantifying the associated cross-tropopause transport a significant challenge. To date, observational data sets do not provide sufficient coverage or resolution to easily overcome this challenge. In addition, ground-based observations are only representative of local processes or extreme events and do not directly inform global behavior. As a result, cross-tropopause transport estimates have relied on global models and reanalyses. However, observational evidence suggests that such models are prone to errors in both the occurrence frequency of tropopause folds and the amount of transport they generate individually. These limitations serve as the basis for our work, and we focus on a new framework to quantify the occurrence frequency of tropopause folds.

 

Existing literature provides various methods to quantify the occurrence frequency of tropopause folds, with some using Lagrangian parcel trajectories and others using tracer-like quantities and dynamical proxies for transport. Results vary greatly in distribution and in amplitude. Overall, because tropopause folds are associated with jet streams, a central problem lies in tracking said jet streams. Existing jet tracking algorithms tend to be complex, computationally expensive, and rely on a variety of ad hoc parameters and thresholds that are based on current climatologies (such as a minimum wind speed threshold). Consequently, these algorithms produce outputs that are sensitive to arbitrary choices and that are not well suited for climate studies.

 

We develop a jet tracking algorithm with two central improvements:

1) it includes temporal information about the evolution of features of interest, by using a time-integrated variable that provides information about parcel transport;

2) it minimizes the use of ad hoc parameters by defining jet features qualitatively, i.e., as spatially and temporally coherent local maxima in parcel transport;

By including temporal information, we are able to track dynamically relevant features, which is a substantial improvement over existing algorithms that use instantaneous meteorological fields. We present a comparison of the jet stream features identified by our algorithm versus existing ones. We also use the output of our algorithm as a jet-relative coordinate system, which allows us to identify tropopause folding events in global data sets, and to quantify their occurrence frequency.
Validation of Hail Identification Algorithm for GPM DPR (version 7)
Authors: Chandrasekar Chandra V
Published: March 2022

Validation of Hail Identification Algorithm for GPM DPR (version 7)

 

Chandrasekar 1, 2 and Minda Le 1

Colorado State University

Finnish Meteorological Institute

Extreme precipitation such as hail has raised interest due to its huge impact to human activities. In the new version of GPM DPR algorithm (version 7), a new Boolean hail product is developed to identify hail along a vertical profile. The  main feature of this  algorithm is for the first time, offers the potential of retrieving a uniform and homogeneous hail dataset on the global scale from radar sensors. The algorithm is built upon the precipitation type index (PTI). PTI is a value calculated for each dual-frequency profile with precipitation observed by GPM DPR.   The dual-frequency ratio slope with respect to height, the maximum of reflectivity and storm top height are three key ingredients composing PTI value.

PTI has been  shown  to be effective in separating various precipitation types such as snow, graupel and hail profiles [1][2][3]. In this research, we focus on validation of hail identification algorithm by analyzing and cross-validating hail observations from various sources including individual hailstorm and on a global scale. Our algorithm will be validating with hailstorms observed by ground validation radar NEXRAD, GMI based hail identification and multiple scattering effect from Trigger module output of DPR level-2 algorithm. The global scale analysis is essential for satellite-based products. We validation this hail product with various global hail maps using radar, radiometer-based algorithms and reports.  

[1] Le, M and V. Chandrasekar, Graupel and Hail Identification Algorithm for the Dual-frequency Precipitation Radar (DPR) on the GPM Core Satellite. J. Meteor. Soc. Japan, Vol. 99, 2021.

[2] Le, M. and V. Chandrasekar, Ground Validation of Surface Snowfall Algorithm in GPM Dual-Frequency Precipitation Radar. J. Atmos. Oceanic Technol., no 36, pp. 607–619, 2019.

[3] Le, M. and V. Chandrasekar, A New Hail Product for GPM DPR Algorithm. IGARSS’, 2021, Jul 12th ~ 16th, Brussels.

 
Rapid quantitative trace element mapping of microbial carbonates by LA-ICP-TOF-MS: Context, results and perspectives
Authors: Jiang Yuxiang , Hohl Simon V. , Huang Xiangtong
Published: March 2022

Trace element compositions of carbonate microbialites are valuable proxies to reconstruct shallow water microbial environments through Earth's history. Most of the published trace element data of microbial carbonates are obtained from bulk digestion or carbonate leaching from sample powders or via in situ laser ablation analysis calibrated to external reference materials such as NIST glasses. However, due to the complex formation mechanism of microbial carbonates, huge compositional differences are associated with spatial and lithological sample heterogeneities that cannot be fully resolved with the current analytical methodologies.

Here, we describe a new method using a high-frequency laser ablation (LA) system (NWR ImageGEO193) coupled to inductively coupled plasma time-of-flight mass spectrometry (ICP-TOF-MS) and external calibration via matrix-matched nanopowder carbonate reference materials to obtain rapid high-resolution quantitative trace element maps.

Our mapping results reveal that detrital elements such as thorium (Th), aluminium (Al), bioactive elements such as cadmium (Cd) iron (Fe) and nickel (Ni), and rare earth elements (REE) have concentration distributions that correspond with the intrinsic bio-sedimentary layering of the samples. Fully quantitative trace element maps are the foundation for follow-up research such as in situ U-Pb dating on truly authigenic carbonate phases or stable novel metal isotope analyses on individual lithified microbial layers to study bio-essential metal uptake in diverse microbial communities through deep times.

Therefore, quantitative trace element mapping via LA-ICP-TOF-MS is a promising method that can rapidly obtain the spatial geochemical characteristics of microbial carbonates.
Applications of soil moisture for three-dimensional landslide thresholds
Authors: Oh Seungcheol , Jeong Jaehwan , Choi Minha
Published: March 2022

In analyzing the trigger of landslides, numerous studies have paid attention to the importance of hydrological variables. Above all, precipitation is the main factor triggering landslides and debris flows. Since pore water pressure rise influenced by rainfall can lead to the reduction of slope stability, many studies tried to determine the rainfall-driven threshold to figure out the conditions of landslide initiation. Though rainfall-driven threshold (e.g., Intensity-duration curve) is simple and straightforward, universal use has been constrained due to the site-specific features, such as hydraulic parameters, soil texture, and anthropogenic activities. Recently, soil moisture is widely applied to enhance the detecting capability of thresholds. Since soil moisture reflects the condition of the ground directly, it can be used more effectively to identify fluctuations in pore pressure. Therefore, this study attempted to use both rainfall and soil moisture for determining the landslide thresholds. Daily precipitation from Global Precipitation Measurement (GPM) IMERG Final run and 3-hourly surface soil moisture from Global Land Data Assimilation System (GLDAS) L4 V2.1 were used to produce hydrological characteristics (i.e., Antecedent Precipitation Index (API) 24-hr accumulated precipitation, antecedent soil moisture, daily soil moisture, and soil moisture increment). Very firstly, two-dimensional relationships were shown to analyze the corresponding reactivity of each factor in the event of landslides. Based on these results, a three-dimensional critical plane was determined. In order to reflect the site-specific characteristics depending on the region, the thresholding process was divided into 2 steps. After obtaining the national scale threshold based on the probability distribution, regional-scale thresholds were optimized for each area. The capability was verified through validation. Results showed compared to the two-dimensional threshold, the three-dimensional critical plane showed similar accuracy rates but lower False Alarm Rates (FAR). In other words, soil moisture increase can detect landslides effectively and the three-dimensional critical plane can help understand the process of landslide occurrence. Furthermore, it seems possible to quantify the landslide vulnerability depending on the critical plane section.
A comparative study on electron contribution to the ring current during CME and CIR driven geomagnetic storms using RAM-SCB simulations and Arase and ground magnetic data
Authors: Kumar Sandeep , Miyoshi Yoshizumi , Jordanova Vania Koleva , Engel Miles , Asamura Kazushi , Yokota Shoichiro , Kasahara Satoshi , Kazama Yoichi , Wang Shiang-Yu , Mitani Takefumi , Keika Kunihiro , Hori Tomoaki , Jun Chae-Woo , Shinohara Iku
Published: March 2022

Geomagnetic storms are the main component of space weather and are driven by coronal mass ejections (CMEs) or corotating interaction regions (CIRs). During the main phase of geomagnetic storms, the ring current enhances and a global decrease in the H component of the geomagnetic field is observed. The storm time distribution of ring current ions and electrons in the inner magnetosphere depend strongly on their transport in evolutions of electric and magnetic fields along with acceleration and loss. Recently, we showed that the electron pressure contributes to the depression of ground magnetic field during the storm time by comparing Ring current Atmosphere interactions Model with Self Consistent magnetic field (RAM-SCB) simulation, Arase in-situ plasma/particle data, and ground-based magnetometer data [Kumar et al., 2021]. In this study, we compare the contribution of electron pressure to the ring current during selected CIR and CME geomagnetic storms using ground observations and the self-consistent inner magnetosphere model: RAM-SCB. The previous results show that the ions are the major contributor (~ 90 %) to the total ring current and the electron contributes ~10 % to the ring current pressure in the post-midnight to dawn sector where electrons flux is higher compared to ions flux. As CIR and CME storms have different origins, we will discuss expected differences in the contribution of electron pressure to the ring current.
The Effect of Topography on Tropical Cyclone Precipitation in the Philippines
Authors: Racoma Bernard Alan , Holloway Christopher , Schiemann Reinhard , Feng Xiangbo , Bagtasa Gerry
Published: March 2022

In this study, we examine the effect of the Cordillera Mountain Range (CMR) in Luzon, Philippines on Tropical Cyclone (TC) precipitation. Using the Weather Research and Forecasting model, we simulated multiple TC events with three different terrain profiles: control, reduced CMR, and enhanced CMR. We find that for most of the TC cases overland precipitation increases as mountain height increases. To further understand the interaction between TC precipitation and the mountain range, we examine the effects of relevant dynamical fields, including mountain slope, incoming perpendicular wind speed, and the moist Froude Number (Fw). We highlight that TC precipitation is strongly and positively correlated with the product of approaching wind speeds and mountain slope. It is hypothesized that stronger winds along steeper mountain slopes translate to vertical motion which in turn causes higher amounts of precipitation, especially during TC events. In contrast,  the linear relationships with other variables are less clear. It is also worth noting that a significant weakening of TCs may cause less rainfall overland, which is an indirect effect of the mountain range on TC precipitation. Understanding the interactions between TCs and mountain ranges may help in regional quantitative precipitation forecasting efforts in the mountainous regions of the Philippines.
Substorm influences on plasma properties distributions in the inner magnetosphere
Authors: Fu Haobo , Yue Chao , Zong Qiu-gang , Zhou Xu-zhi
Published: March 2022

The plasma properties in the inner magnetosphere play critical roles in plasma dynamics by changing magnetic field configurations and generating the ring current. Geomagnetic substorms, especially intense substorms can significantly influence inner magnetosphere. This study presents our preliminary statistical results of plasma properties and their substorm dependence at the equatorial plane based on the Van Allen Probe observations. We find that both H+ and O+ pressure increases significantly during substorms, and the pressure ratio of O+ to H+ also increases. The peak of H+ pressure is almost fixed around L=4, while that of O+ moves inward as the substorm intensifies. In addition, substorms can significantly change the ion energy distributions. They will increase the proportion of pressure provided by the lower energy components of H+ (E < ~100keV), especially in lower L-shells. At the same time, they decrease the contribution to the plasma pressure from lower energy components of O+, which shows almost no L-shell dependence. During quiet times, the perpendicular current density distributes roughly symmetrically, with negative value inside (L < ~4.5) and positive value outside. During substorms, the current density enhances and shows asymmetry with higher current density from the pre-dusk to the post-midnight. The parallel current density caused by the pressure gradient also increases with substorms. These field-aligned currents (FACs) enter the ionosphere at dusk and move upward at dawn, as region II FAC.
Measurements of sediment backscatter in a flume: preliminary experiment results and prospective 
Authors: Lurton Xavier , Roche Marc , van Dijk Thaiënne , Berger Laurent , Fezzani Ridha , Fietzek Peer , Gastauer Sven , Klein Breteler Mark , Mesdag Chris , Simmons Steve , Parsons Daniel
Published: March 2022

Multifrequency single- and multibeam echosounders are today mature technologies for underwater mapping and monitoring of the seafloor and water column. However, the current scarcity of reference models (checked with field measurement results including detailed geoacoustical groundtruthing) for seafloor backscatter angular response and suspended sediment scattering hampers the generation of applicable information. In this context, defining heuristic models derived from measurements made in a well-controlled environment should optimize the use of backscatter data for ocean observation and management. Such reference measurements could be conducted in flumes designed for hydrodynamics and sedimentology experimental studies, since such facilities constitute well-dimensioned and equipped infrastructures adapted to the deployment of echosounders over controlled sedimentary targets. In order to check the feasibility of this concept in terms of acoustical measurement quality, a preliminary experiment was conducted in the Delta Flume (dimensions 291 x 5 x 9.5 m), as a preparation for more comprehensive systematic measurement campaigns. Multifrequency single- and multibeam echosounder data were recorded from the flume floor at various angles and from in-water fine sand plumes. The results reveal that reverberation caused by the flume walls and infrastructure does not interfere significantly with bottom targets and that fine sand plumes in the water column can be detected and measured for various particle concentrations. Future comprehensive experiments (in preparation) will feature multi-frequency multi-angle measurements both on a variety of sediment types and interface roughness, and on plumes of various sediment grain size, shape and concentration.
Effect of nitrogen limitation and soil biophysics on Holocene greening of the Sahara
Authors: Lee Jooyeop , Hong Jinkyu , Claussen Martin , Kim Jeongwon , Hong Je-Woo , Song In-Sun
Published: March 2022

The so–called Green Sahara (GS), wet and vegetative Sahara region in the early to mid–Holocene, provides useful information on our climate simulation because it is a consequence of complex interaction between biophysical and climatic processes. It is still a challenge to simulate the GS in terms of vegetative extent and precipitation using the current climate models. This study attempts to simulate the 8,000 year ago Green Sahara by using the state–of–the–art Earth system model CESM that incorporates the nitrogen cycle and the soil–precipitation feedbacks. Our study puts more emphasis on the impact of soil biophysical properties and soil nitrogen influenced by soil organic matter on the simulation of the GS. In this coupled simulation, vegetation interacts with changes in soil properties and soil organic matter by phenology, decomposition and allocation of carbon and nitrogen. With changes in the Earth’s orbit and dust in the early to mid–Holocene, the model simulates increased precipitation in North Africa, but does not capture the extent of the GS. Our analysis shows that the Holocene greening is simulated better if the amount of soil nitrogen and soil texture are properly modified for the humid and vegetative GS period. Soil biochemical and physical properties increase precipitation and vegetation cover in North Africa through their influence on photosynthesis and surface albedo and their consequent enhanced albedo– and evapotranspiration–precipitation feedbacks. Our findings suggest that future climate simulation needs to consider consequent changes in soil nitrogen and texture with changes in vegetation cover and density for proper climate simulations.

More information on this work can be found at
Lee et al. (2022) Effect of nitrogen limitation and soil biophysics on Holocene greening of the Sahara, Climate of the Past, accepted.

 
Simulation of 3D transient superstructures in mantle convection and variable viscosity via the Lattice Boltzmann Method
Authors: Mora Peter , Morra Gabriele , Yuen Dave
Published: March 2022

Transient superstructures in mantle convection whose life and morphology vary with Rayleigh and Prandtl number have recently been demonstrated. These superstructures appear to be a two-scale phenomenon where smaller scale rolls organize into larger scale convection cells. Simulation of such superstructures requires the ability to model 3D convection in box with very large width/height ratio of order greater than 10, and with resolution to resolve the thermal boundary layer at Rayleigh numbers of 108 to 1010, respectively at least 100 height levels and 200 height levels. We achieve this with an efficient parallel implementation of the Lattice Boltzmann Method using Python which operates with high efficiency and linear speedup on thousands of cores. We present simulations with Rayleigh numbers of up to 1010 and Prandtl numbers from 1 to 100 to illustrate covering regimes from a magma ocean to solid mantle convection. We further present simulations using the LBM to model variable viscosity – specifically, temperature dependent– and illustrate the existence of pulsating plumes. We further demonstrate power law scaling between Nusselt number and Rayleigh number Nu  ~ Rag, which to first order is consistent with the Grossmann and Lohse theory.
Assessing the viability of using CHIRPS-GEFS for landslide forecasting in the Lower Mekong Region
Authors: Laverde-Barajas Miguel , khan Sana , Kirschbaum Dalia , Stanley Thomas , Meechaiya Chinaporn , Jayasinghe Susantha , Towashiraporn Peeranan
Published: March 2022

The Lower Mekong region is particularly prone to natural hazards caused by extreme rainfall. During monsoon seasons from June to October, heavy rainfall triggers severe flash floods and landslides, posing a threat to human lives and livelihoods. Global forecast products struggle to provide reliable estimates of extreme rainfall at regional scale, which is a big challenge in their integration in early warning systems. A newly released version of Climate Hazards Center InfraRed Precipitation with Stations (CHIRPS) Global Ensemble Forecast System (GEFS) dataset is a bias-corrected and downscaled product derived from National Centers for Environmental Prediction (NCEP)-GEFS. CHIRPS-GEFS product provides up to 16 days of rainfall forecasts at 5km/daily spatio/temporal resolution. This study evaluates the spatial and temporal performance of the CHIRPS-GEFS for extreme precipitation in the Lower Mekong region during monsoon seasons from 2014 to 2019. Rainfall forecasts from 1 to 5-days lead-time are analyzed against the bias-corrected Integrated Multi-satellitE Retrievals for GPM (IMERG) over the lower Mekong region. The performance is assessed using both categorical and continuous statistics such as the probability of detection, false alarm ratio, critical success index, correlation coefficient, and root mean squared error. Results describe the spatial and temporal strengths and limitations of the CHIRPS-GEFS and the influence of geomorphological conditions on its performance. This analysis provides valuable information on CHIRPS-GEFS possible integration in the lower Mekong landslide forecasting model for region-based landslide hazard assessment and situational awareness (LHASA)  along the lines of the global LHASA framework. 