bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatial Variability of Rainfall Erosivity over India
Authors: Raj Ravi , Saharia Manabendra , Chakma Sumedha , Rafieeinasab Arezoo
Published: March 2022

Indian is worst affected by soil erosion, especially due to erosion induced by rainfall. A factor of Universal Soil Loss Equation (rainfall erosivity factor) needs to be estimated throughout the country to assess the soil erosion in the country. Indian climate is dominated by monsoons, and their intensity and distribution vary significantly throughout the country. Rainfall erosivity is solely derived from the rainfall intensity, which is a function of climatic properties. In this study, the distribution and variability of the rainfall erosivity factor (R factor) had been analyzed in different regions and sub-divisions of India as classified by India Meteorological Department (IMD). For estimation of rainfall erosivity, the widely adopted principle of kinetic energy and rainfall intensity had been used. A well-known precipitation index, Modified Fournier Index (MFI), was also calculated to check its influence on the R factor. Regression equations in the form of power-law are derived for all regions of the country to establish the relationship between the R factor and MFI. Further, an analysis at the sub-divisional level was also performed to visualize the spatial variability of the R-factor throughout the nation. South peninsula India with the lowest average R factor of 615.61 MJ-mm/ha/h/yr, was recognized as least vulnerable to rainfall erosivity while the East and Northeast India was recognized as most susceptible with a highest R factor of 3312.39 MJ-mm/ha/h/yr. About 36% of the entire subdivisions of the country were spotted with an average rainfall erosivity factor higher than the national average rainfall erosivity factor, and hence they are more prone to erosion induced by rainfall. Estimating rainfall erosivity factors at sub-divisional and regional levels will help policymakers and watershed experts prioritize the watershed management practices to counter soil erosion induced by rainfall erosivity.

Keywords – Rainfall erosivity, IMD, Spatial variability, Climate, Precipitation index
On the Growth and Development of Non-linear Kelvin-Helmholtz Instability at Mars: MAVEN Observations
Authors: Poh Gangkai , Espley Jared , Nykyri Katariina , Fowler Christopher , Ma Xuanye , Xu Shaosui , Hanley Gwen , Romanelli Norberto , Bowers Charles , Gruesbeck Jacob , DiBraccio Gina
Published: March 2022

We analyzed MAVEN observations of fields and plasma signatures associated with an encounter of fully-developed Kelvin–Helmholtz (K–H) vortices at the northern polar terminator along Mars’ induced magnetosphere boundary. The signatures of the K–H vortices event are: (i) quasi-periodic, “bipolar-like” sawtooth magnetic field perturbations, (ii) corresponding density decrease, (iii) tailward enhancement of plasma velocity for both protons and heavy ions, (iv) co-existence of magnetosheath and planetary plasma in the region prior to the sawtooth magnetic field signature (i.e. mixing region of the vortex structure), and (v) pressure enhancement (minimum) at the edge (center) of the sawtooth magnetic field signature. Our results strongly support the scenario for the non-linear growth of K–H instability along Mars’ induced magnetosphere boundary, where a plasma flow difference between the magnetosheath and induced-magnetospheric plasma is expected. Our findings are also in good agreement with 3-dimensional local magnetohydrodynamics (MHD) simulation results. MAVEN observations of protons with energies greater than 10 keV and results from the Walén analyses suggests the possibility of particle energization within the mixing region of the K–H vortex structure via magnetic reconnection, secondary instabilities or other turbulent processes. We estimated the lower limit on the K–H instability linear growth rate to be ~5.84 x 10-3 s-1. For these vortices, we estimate the lower limit of the instantaneous atmospheric ion escape flux due to the detachment of plasma clouds during the late non-linear stage of K–H instability to be ~5.90 x 1026 particles/s, which is agrees with earlier studies for the Venusian plasma clouds but ~two orders of magnitude larger than that calculated for Mars. 
Modelling of pedogenic carbonates formation in karst soils – a case from Dalmatia (Croatia)
Authors: Šušnjar Josip , Domínguez-Villar David , Bensa Aleksandra , Švob Mirna , Krklec Kristina
Published: March 2022

Pedogenic carbonates are secondary carbonate deposits that are often found in soils developed over carbonate rocks in Mediterranean region. Their formation is a result of dissolution and reprecipitation of existing geogenic, biogenic and/or pedogenic carbonates. Intensity of the dissolution processes affecting carbonates depends on multitude of factors but is mostly controlled by soil water drainage and concentration of soil air CO2.

While percolating through soils and carbonate rocks, water dissolves carbonate minerals until reaching saturation state. Change in environmental conditions impacting concentration of soil air CO2 (e.g., increase of temperature, decrease of soil water content), change of the soil water chemistry and evapotranspiration can lead to supersaturation of water in regard to Calcite and formation of pedogenic carbonates. In case of physicochemical precipitation, pedogenic carbonates precipitate in form of diffuse, small crystals and nodules. On the other hand, biologically influenced precipitation commonly results in different morphologies such as rhizolits, bacterial/fungal mats, etc. Pedogenic carbonates can occur in wide range of climates, thus their morphology and accumulation depth depend on mean annual precipitation. If sufficient time has passed, translocation of carbonates in the soil profile results in formation of calcic horizon.

We studied a 0.6 m deep Red Mediterranean Soil profile in Dalmatia (Croatia) having a calcic horizon at the bottom. Diffuse calcite particles and small nodules forming this horizon record different events of dissolution and precipitation. Based on data on soil temperature, soil water content, soil bulk electrical conductivity and soil air CO2 collected during a 3-month monitoring period we developed a thermodynamic model for dissolution and precipitation of calcite in the soil. Results show that soil air CO2 (affected by soil water content and temperature) is the main control of the calcite reactions. Furthermore, during the monitoring period 83% of the calcite dissolved was reprecipitated as pedogenic carbonate. Therefore, although dissolution is the main process governing denudation rate of karst areas (i.e., lowering of the surface), formation of pedogenic carbonates in soils could impact denudation rate of carbonate terrains.

Acknowledgements

This work is part of the research project “Inter-comparison of karst denudation measurement methods” (KADEME, IP-2018-01-7080) and “Young Researchers’ Career Development Project – Training New Doctoral Students” (DOK-2021-02) financed by Croatian Science Foundation.
Tree-ring δ2H records of lignin methoxy indicate spring temperature changes since 20th century in the Qinling Mountains, China
Authors: Lu Qiangqiang , Liu Xiaohong , Tan Liangcheng , Keppler Frank , Treydte Kerstin
Published: March 2022

Stable hydrogen isotope ratios (δ2H) of wood lignin methoxy groups (δ2HLM) in tree rings of the mid-latitude forests are increasingly applied to reconstruct the regional δ2H signatures of precipitation and the mean variation of annual temperature. To date, knowledge about climate dynamics in biogeographic boundary between subtropical and warm temperate region still remains uncertain. We here investigated the climate significance of annually resolved tree-ring δ2HLM chronologies from two typical conifer species along a north-ridge-south transect of the Qinling Mountains (central China) over the 20th century. The δ2HLM chronologies of Pinus tabulaeformis on the both slopes revealed negative shift in the first half century, but turning to pronounced positive trends from 1955. In contrast, the chronologic changes in timberline Abies fargesii showed a continuous increase during the period from 1901 to 2018. Climatic response indicated a significant spring temperature signal recorded in the δ2HLM chronologies. The abrupt changes in δ2HLM variability at the lower elevation revealed topography-related temperature signals which superimpose strong local moisture effects, thereby demonstrating the enhanced differences in climate between southern and northern slopes of the Qinling Mountains, since the 1950s. Our data also indicate that alpine trees might respond consistently to large scale global warming in the absence of local disturbances. Overall, the long-term variations in mountainous climate but geographic-specific characteristics of north versus south slopes would result in a varied ecological and hydrological alteration, and thus influence the sustainable vegetation development for the Qinling National Park in the future.
Deciphering the Contributions of Volcanic and Environmental Events to Temporal Variations of the Regional Velocity Structure at the Kluchevskoy Volcano Group (Kamchatka, Russia)
Authors: Makus Peter , Sens-Schönfelder Christoph , Tilmann Frederik , Walter Thomas R.
Published: March 2022

Kamchatka, a remote peninsula in eastern Russia, is home to the Kluchevskoy volcano group, one of the largest and most active clusters of subduction zone volcanoes worldwide. Regular eruptions, volcanic and tectonic earthquakes, but also strong meteorological variations leave an imprint on the regional seismic velocity structure. We quantify the temporal velocity variations by applying the method of ambient seismic noise interferometry to waveform data recorded by the temporary KISS deployment and the permanent Kamchatka network. Due to its ubiquitous nature, ambient seismic noise allows for far denser temporal sampling than, e.g., active source or earthquake coda interferometry. However, source variability related, for example, to volcanic tremor activity affects the results retrieved by this method and can lead to decreased reliability. Here, we investigate the impact of the aforementioned environmental factors on the Green’s function of the medium using SeisMIC (Seismological Monitoring using Interferometric Concepts) – a new Python software to conduct noise interferometry surveys. In addition, we discuss the impact of the frequent volcanic tremors and other local seismic events on the stability of the computed Green’s function estimations (i.e., cross-correlations).
Changes in the frequency and extremity of rain-on-snow events in the warming climate
Authors: Hotovy Ondrej , Jenicek Michal
Published: March 2022

Seasonal snowpack significantly influences the catchment runoff and thus represents an important input for the hydrological cycle. A shift from snowfall to rain is expected in the future due to climate changes, as well as changes in the precipitation distribution and intensity. As a result, changes in the frequency and extremity of rain-on-snow events, which are considered to be one of the main causes of floods in winter and spring, may occur.

The objective of this study is 1) to evaluate the frequency, extremity, and trends in occurrence of rain-on-snow events in the past based on existing measurements, and 2) to simulate and evaluate the effect of predicted increase in air temperature on the occurrence of rain-on-snow events in the future. We selected several near-natural mountain catchments in Czechia and Switzerland with significant snow influence on runoff and with available long-time series of daily hydrological and meteorological variables. A semi-distributed conceptual model, HBV-light, was used to simulate the individual components of the water cycle at a catchment scale. The model was calibrated for each of study catchments by using 100 calibration trials which resulted in respective number of optimized parameter sets. The model performance was evaluated against observed runoff and snow water equivalent. Each study catchment was divided into several elevation zones by 100 m, for which all data at a daily resolution were distributed by the model. Rain-on-snow events definition by threshold values for air temperature, rain intensity and snow depth allowed us to analyze inter-annual variations and trends in rain-on-snow events during the study period 1965-2019 and in the future.

The results show that a change of rain-on-snow events related to increasing air temperature differs among individual study catchments and individual elevation zones during winter season. Since both air temperature and elevation seem to be an important rain-on-snow drivers, there is an increasing rain-on-snow events occurrence due to a decrease in snowfall fraction. In contrast, a decrease in total number of events was observed due to the shortening of the period with existing snow cover on the ground. Modelling approach also opened further questions related to model structure and parameterization, specifically how individual model procedures and parameters represent the real natural processes. To understand potential model artefacts might be important when using HBV or similar bucket-type models for impact studies, such as modelling the impact of climate change on catchment runoff.
Rockmagnetic based environmental reconstruction of Galería and Gran Dolina caves in Sierra de Atapuerca (Burgos, Spain)
Authors: D'Arcangelo Serena , Martín-Hernández Fátima , M. Parés Josep
Published: March 2022

Magnetic properties of sediments can furnish an environmental reconstruction of the deposition time. In our study we intend to understand the climatic – paleoenvironmental conditions at the time the earliest hominins found in Europe, and especially the well-known archaeological sites at Sierra de Atapuerca, in Burgos, Spain. The sites assemblage is found in a multi-layered karstic system, and includes a number of caves filled with both interior (distal) and entrance sediments. We focused our attention on two caves, which belong to the so-called “Trinchera” (trench) sites, namely Galería and Gran Dolina. The latter has produced thousands of fossils and artefacts since 1995, when the first hominin remains were reported, and soon became a Pleistocene landmark in studies on early human settlement outside the African continent. Our already published study on Gran Dolina presents more variability of magnetic properties in cave-entrance sediments than in the cave-interior, as expected for the exterior influence on the grain size and iron oxides concentration.

Now, we start to investigate the Galería site to correlate it with the nearest cave and to better understand the paleoenvironmental context at the time early humans inhabited the area. In particular, we confined our attention to identify the magnetic minerals present into Covacha de los Zarpazos (the lower studied part of Galería) with backfield and IRM curves determined by a magnetic Variable Field Translation Balance (VFTB). This analysis allows us to individuate a more precised reconstruction of the environmental conditions of the deposition time, also with a comparison of a pollen study and X-Ray Fluorescence (XRF) in-situ study for a major precision.
 Understanding the Dynamical Relation of MJO with Indian Summer Monsoon Onset and Progress 
Authors: lenka smrutishree , Gouda Krushna Chandra , Joseph Chennemekeril Mathew
Published: March 2022

Madden–Julian oscillation (MJO) is an important oceanic and atmospheric phenomenon in the tropical belt around the globe which influences the global weather & climate system. The process mainly results east ward propagating band of rain clouds and its circulation pattern has a remarkable effect on the global annual rainfall. Monsoon onset is important as the rainfall transition and its progress has direct impact on the sectors like agriculture, water, health and economy etc. over the continent of India. As there are different phases in the MJO so it clearly affects the intra-seasonal and inter seasonal variability of rainfall, like for few phases it gives monsoon break type rainfall distribution whereas for some other phases it gives active rainfall distribution. It is also possible that the MJO phases have direct impact on the dynamics and physics during the onset as well as the progress of south west monsoon in India. In this study the association of different MJO phases and the resultant rainfall dynamics during onset period are analyzed using the multi-source weather observations for 68 years (1951-2018). The link of both active and weak phase of MJO and rainfall (duration and intensity) during the onset phases and thereafter during the progress of monsoon are quantified and presented. Also the spatial relation of the MJO location and the regional rainfall along with other oceanic parameters like Sea Surface Temperature, heat flux etc. are evaluated using the observed and reanalysis product. It is observed that mostly the active (weak) phase leads to early (late) onset over Kerala coast in India. Finally the tele-connection of progress of monsoon in continental India and the MJO phases are discussed. This association study will certainly help the researchers in better understanding of the MJO and regional rainfall dynamics and this information can be integrated with numerical weather prediction models for better and accurate prediction of the monsoon onset as well as the rainfall in the sub continent.

 
The Ar-Hötöl surface rupture along the Khovd fault (Mongolian Altay)
Authors: Davaasambuu Battogtokh , Ferry Matthieu , Jean-Francois Ritz , Munkhuu Ulziibat
Published: March 2022

The Ar-Hötöl surface rupture along the Khovd fault (Mongolian Altay)

 

Battogtokh Davaasambuu1,2, Matthieu Ferry1,*, Jean-Francois Ritz1 and Ulziibat Munkhuu2

Géosciences Montpellier, University of Montpellier, CNRS, France

Institute of Astronomy and Geophysics, Mongolian Academy of Sciences, Mongolia

 

Abstract

The Khovd fault is one of the major active faults of the Altay but has been little studied. Detailed mapping based on satellite imagery shows that the Khovd structure exceeds 550 km in length and displays different types of complex rupture segmentation, fresh and mature surface ruptures and a number of co-seismic and cumulative offsets along its entire length.

We present a 1:200,000 scale map of the Ar-Hötöl surface rupture along the Khovd Fault in the Mongolian Altay, presumed to be the surface expression of a Mw ~ 7.8 earthquake that was felt regionally in 1761 CE. The detailed mapping is based on a multi-scale approach combining a range of airborne and terrestrial imaging and topographic techniques: Sentinel-2, Pleiades, TanDEM-X, UAV, and terrestrial laser scanning. This effort led to the detailed quantification of right-lateral and vertical offsets ranging from ~ 1 m to ~ 4 km over a continuous rupture length of 238 km. The distribution of the smaller offset class documents the surface deformation associated with the last surface-rupturing earthquake. Its analysis yields a robust segmentation model comprising 6 segments 18 to 55 km in length, a maximum co-seismic slip value of 4.5 m ± 0.5 m located near the center of the rupture. Our detailed remote sensing and field observations precise the varying kinematics along strike, bring new evidence of repeated faulting and confirm a moment magnitude of 7.8 ± 0.3.

The aim of the present research work is to reveal the main sources of potential destructive earthquakes by identifying the location of past large earthquakes along the fault and estimate their magnitude and recurrence period. Our results would contribute to improve seismic hazard estimation for population of the Altay Mountains.

 

Keywords: active fault, surface rupture, Altay Range

 
Monitoring nanoparticle progression and fate in the soil using spectral induced polarization 
Authors: Ben Moshe Shany , Furman Alex
Published: March 2022

The fate and transport of metallic nanoparticles (NPs) in the soil has been a major concern over the last decade due to the increasing use of NPs in many industries and their appearance in the environment. However, the study of NP fate and transport traditionally relies on intensive sample collection ana chemical analysis. In this work we use spectral induced polarization (SIP) to monitor the transport of metallic NPs in soils. In SIP, an alternating current in wide range of frequencies is injected, and the phase and amplitude difference between the injected and induced potential are measured. Our experimental setup involves flow-through columns packed with different types of soil, through which a suspension of NPs with different ionic compositions is passed. Electrical potentials are recorded at three locations along the column. The analyzed SIP measurements allow not only non-invasive, non-destructive monitoring of the NP’s progression through the soil but also deduction of the NPs’ fate and transport patterns through combination with elemental analysis. The sensitivity of SIP to the presence of the NPs is high and was found to be correlated to their progression in the soil even in low and environmentally relevant NP concentrations (<5mg/L).  Our results indicate that SIP is a promising method for monitoring of NPs in the soil and with further research may serve as an easy and efficient alternative to the standard methods that involve extensive water and soil sampling.
An efficient multi-scale modelling  framework for assessment of coastal flood events
Authors: Benito Lazaro Irene , Muis Sanne , Aerts Jeroen , Ward Philip , Eilander Dirk
Published: March 2022

Flood risk in coastal areas is projected to increase with climate change, affecting more coastal communities and their economies. An accurate estimation of risk is essential to reduce the potential impact of extreme flood events. Recent studies have focused on improving the simulation of extreme sea levels at large scales. However, the inundation mapping derived from those water levels is usually done using simple static approaches that can lead to an overestimation of flood extents. This research provides a step forward towards global-scale modeling of coastal inundation due to tropical cyclone events. We are developing a model framework to rapidly and realistically simulate flood hazard in any coastal region. The framework will incorporate three main improvements compared to previous approaches: (1) use of a multi-scale modelling approach that allows for the use of global models and datasets for local flood hazard assessments at high-resolution; (2) move from simple static inundation models towards more physically-based approaches; and (3) move from homogeneous return periods towards event-based modeling. For this purpose, we use the Oceanographic Multipurpose Software Environment which enables model coupling across different spatial scales and physics. Refined local models are nested in the Global Tide and Surge Model for a better representation of the extreme sea levels driven by tropical cyclones. Next, we will combine the water levels with SFINCS and the Synthetic Tropical cyclOne geneRation Model (STORM) to map inundation for a large number of tropical cyclone events.  Here we will present the validation of the framework for three historical events, that is Idai, Haiyan and Katrina.
The influence of resolved gravity waves in the stratosphere for subseasonal hindcasts of the troposphere during SSW events
Authors: Wicker Wolfgang , Polichtchouk Inna , Domeisen Daniela
Published: March 2022

Sudden stratospheric warmings (SSW) are major weather events in the stratosphere with a long-lasting impact on tropospheric weather conditions and, thus, offer a great potential to extend the predictability of surface weather on subseasonal time scales. However, underestimating the warming signal in the stratosphere itself hinders prediction systems to exploit this source of tropospheric predictability. In this study, hindcast experiments with the ECMWF IFS model reveal sensitivity to vertical resolution both for the amplitude and the persistence of the stratospheric warming signal and the prediction skill of surface variables. A potential mechanism for the extended and strengthened warming in the stratosphere with higher vertical resolution are better resolved gravity waves that break in the proximity of the zero-wind line in the upper stratosphere. The enhanced gravity wave drag with higher vertical resolution increases positive temperature anomalies in the middle stratosphere, consistent with anomalous subsidence over the polar cap during the SSWs. Nudging experiments confirm that the enhanced gravity wave drag results directly from increased vertical resolution, as opposed to the modified background state, and that increased surface skill and longer predictable lead times are of stratospheric origin.
Drivers of sea level variability in the Baltic/North/Nordic Seas using neural networks
Authors: Poropat Lea , Heuzé Céline
Published: March 2022

Sea level is rising, threatening coastal population and infrastructures. While the causes for global sea level rise are relatively well determined and the projections can be made based on most likely climate scenarios, sea level changes in coastal regions are far less understood. Apart from the global temperature rise and the melting of ice sheets and glaciers, coastal areas are also affected by the spatio-temporal temperature and salinity variations, atmospheric conditions, and even vertical land motions, such as those due to glacial isostatic adjustment. It is therefore necessary to determine which factors contribute most to the sea level change in each specific region, in order to mitigate the effect sea level changes will have on local infrastructure. 
We here use long short-term memory (LSTM) neural networks to find the connection between the sea level variations and its many potential drivers in the Baltic, North, and Nordic Seas, at daily to decadal scales. We test all the different combinations of local atmospheric (surface pressure, wind, and precipitation from reanalysis) and oceanic (temperature and salinity, from in-situ observations), along with the remote ones (e.g. Greenland ice sheet runoff, large scale water mass circulation) to predict sea level variations at selected locations that have uninterrupted long-term (>50 years) tide gauge observations.
By comparing the quality of sea level prediction from these different combinations, we find that the long-term sea level trend and low-frequency variations at most locations in our region of interest are mainly driven by the temperature rise, both local and remote, while the higher frequency variations are predominantly driven by the changes in local wind. As expected, northern locations are also affected by glacial isostatic adjustment, which counteracts the sea level rise. Precipitation, even during major storm events, seems to play an insignificant role in our region. The exception is the Baltic Sea, where wind plays less of a role, and the sea level is more affected by the influx of fresh water.  While most regions are affected by sea level rise to some extent, because the causes for the local sea level changes vary, the protection from flooding and the warning techniques have to be adapted for each location.
An insight into Whakaari’s conduit: How altered tuffs and subsurface pressures can control volcano dynamics
Authors: Kanakiya Shreya , Adam Ludmila , Rowe Michael , Lindsay Jan , Esteban Lionel
Published: March 2022

Hydrothermal sealing is one of the mechanisms thought to aid pressure build-up within a volcano. Whakaari (White Island), New Zealand’s most active volcano, has a long history of phreatic and phreatomagmatic eruptions, and is ideally suited for an investigation into seal development from conduit-filling lithologies, where little prior experimental evidence exists. Here we provide an insight into Whakaari’s conduit by studying variably altered rocks ejected as ballistics. We find that hydrothermal alteration, particularly acid sulphate alteration, affects conduit-filling lithologies, lavas and tuffs, differently. In inherently low porosity lithologies like lavas, alteration increases fluid pathways by net dissolution of primary minerals and reduces rock stiffness. Counterintuitively, in tuffs that are inherently porous and permeable, alteration decreases fluid pathways by net precipitation of secondary minerals and increases rock stiffness. Such alteration-related pore filling of tuffs together with pore compaction under subsurface pressures can develop zones of low porosity and permeability within the volcano's conduit. When fluid injection rates are high, these zones could aid pressure build-up and predispose the volcano to eruptions. We discuss these results with observed seismicity at Whakaari and provide implications for ground deformation.
Geochemistry of emerald from the Colombian Emerald belts: Genetical implications
Authors: Ramirez Juya Valeria , Betancur Camilo Andres , Garcia Toloza Javier , Angarita Luis
Published: March 2022

Colombian emeralds are widely recognized for their unique gemological and geological features; The first one involves color, which depend on the proportions of their minor and trace elements. The latter is associated with its genesis, which implicates hydrothermal brine fluids affecting the sedimentary host rock. Thus, to propose an emerald finger-print for each belt, we use geochemical methods as Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), ternary and binary diagrams, and principal component analysis (PCA) in 258 emerald samples; 117 from the eastern emerald belt (EEB) and 141 from the western emerald belt (WEB).

The chromophores elements relation (Cr, V, and Fe) is used to differentiate emeralds from different geographical proveniences, that approach is valid with Colombian emeralds. Besides, in this study, we notice differences betwixt the V/Cr relationship in both belts: in the EEB, the proportion is lower than 0.75, and in the WEB, this proportion is upper than 0.75, and in most of the cases is over 1. This tendency is also remarkable in the ternary plot that includes iron.

Furthermore, other chemical elements have a particular behave depending on the belt, is the case of Na and Mg; in this study, we introduce a binary plot as a new method where the linear relation between those elements permit expressing a mathematical equation to distinguish each belt (Na=0,8Mg+362), where there is a cut-off point in Mg=3225 and Na=2940, the data lower of that point represent samples of the EEB, and the data upper come from the WEB.

In detail, the basin environment of each belt controlled the abundance of heavy metals; in the WEB, the quantity of those elements is higher. Evidence of this is the higher volume of sulfides and oxides. Except for the Cr content, this variant could be due to a previous stage of mineralization that includes Cr-rich muscovites. In the EEB, the Na and K content in the emeralds is lower because the rock suffers feldespatic enrichment in layers (Santa Rosa and Chivor formations). Owing to that, the temperature is enough to generate a massive albitization process affecting the original lithology of the stratigraphic sequence.
Updating the GNSS velocity field in the Eastern Betics
Authors: Portela Fernández Juan J. , Staller Alejandra , Béjar-Pizarro Marta , Khazaradze Giorgi
Published: March 2022

The Eastern Betics, located on the SE of Spain, is one of the areas with the highest seismic activity within the Iberian Peninsula. The Eastern Betic Shear Zone (EBSZ) is comprised by a set of active, slow-moving faults, which are partially absorbing the ~5 mm deformation caused by the convergence between the Eurasian and Nubian plates. The precise kinematics of these faults remains unclear to this date, due to their slow slip rates and the distributed strain across the region. 

Over the past years, several studies have focused on this area, especially after the devastating 2011 Lorca earthquake (Mw 5.1). However, there is a lack of precise GNSS observations in the central area of the EBSZ. Therefore, we present here an updated GNSS velocity field of the central EBSZ, which includes all the available continuous stations in the area, as well as continuous and campaign observations carried out under the GeoActiva project (CGL2017-83931-C3-3-P). 

Additionally, we discuss alternative deformation sources affecting the GNSS observations (other than those of tectonic origin), such as the human-induced subsidence in the Guadalentín River Basin. We use Sentinel-1 SAR images to identify the affected areas and to quantify the impact on the GNSS velocities.

This work has been developed in the framework of GeoActiva project (CGL2017-83931-C3-3-P, funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”) and e-Shape project (H2020 programme, Grant Agreement 820852), as well us under Grant FPU19/03929 (funded by MCIN/AEI/10.13039/501100011033 and by “FSE invests in your future”).
Adjoint-state Method Based Strategy for Non-linear Seismic AVO Inversion
Authors: Ahmed Nisar , Weibull Wiktor Waldemar , Grana Dario
Published: March 2022

Seismic amplitude versus offset inversion has gained increased attention over the years and is a pragmatic tool applied to retrieve the seismic and petrophysical properties of the geological layers. The prediction of these petro-elastic properties plays an important role in litho-fluids identification and quantitative seismic reservoir characterization. However, imaging of these subsurface variables from the pre-stack seismic data requires minimizing the objective function and is generally solved by using a gradient-descent based optimization method. This method requires computing the gradients of the cost function with reference to the rock’s variables. We have introduced a model-based non-linear AVO inversion strategy that is based on the computation of the adjoint-state gradients. The forward seismic modelling is carried out by convolving the seismic wavelet with the reflectivity series modelled by using the linearized AVO approximation. The optimization method known as L-BFGS is implemented to attain the best optimal model. The novelty of this work is the adjoint-state solution of the linearized AVO equation. This inversion method has been successfully applied on single and multi-traced seismic data simulated with different seismic noise levels. The modelled examples show that the presented non-linear inversion method accurately extract the seismic properties including seismic (P and S) wave velocities and bulk density. Even at some realistic seismic noise levels, the true and extracted model show good agreement which demonstrates the wide application to solve the AVO inverse modelling problems.
Iron speciation throughout a karst pedosedimentary record in South of Italy
Authors: Giannetta Beatrice , Cassetta Michele , Oliveira de Souza Danilo , Mariotto Gino , Aquilanti Giuliana , Zaccone Claudio
Published: March 2022

A 3-m thick sediment was found in a limestone mine located in the Apulia region (south of Italy), at a depth of 25-30 m from the current ground level. Samples from 5 layers were investigated by X-ray Absorption Near Edge Spectroscopy (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) at the iron (Fe) K-edge, paired with Raman spectroscopy (RS) and thermal analysis.

The pedosediment record under investigation represents a peculiar stratigraphic series showing complex features related to the Fe dynamic.

From a technical point of view, the challenges of phase identification in Fe oxides are many, but the application of multiple techniques provides sufficient evidence for the identification and discrimination of Fe phases. The combination of Fe XANES and EXAFS allowed to get information on the Fe speciation and its local structure. In detail, ferrihydrite is the most abundant Fe species, followed by goethite and minor amounts of hematite. Ferrihydrite content decreases with depth, where goethite and hematite occur. The presence of ferrihydrite, only detected by Linear Combination Fitting (LCF) on the first-derivative XANES spectra and on the EXAFS spectra, suggests that redox cycling of Fe occurred in these sediments. In addition, higher contents in Fe(III) complexed by organic matter is found in the top and deepest layer.

Generally speaking, RS and thermal analysis might present a promising tool to unravel some mineralogical components such as calcite, goethite and some Mn-oxides. Unlike for the identification of some Fe-bearing minerals like ferrihydrite, RS seems to be not well suited and this aspect require further investigations.

Definitely, this study confirms that each layer has preserved the distinct features that relate to its time of deposition. We underline how a multidisciplinary approach is strongly required to obtain reliable records when peculiar environments like karst pedosequences are investigated.
Coupled impacts of sea ice variability and North Pacific atmospheric circulation on Holocene hydroclimate in Arctic Alaska
Authors: Broadman Ellie , Kaufman Darrell , Henderson Andrew , Malmierca-Vallet Irene , Leng Melanie , Lacey Jack
Published: March 2022

Arctic Alaska lies at a climatological crossroads between the Arctic and North Pacific Oceans. The modern hydroclimate of the region is responding to rapidly diminishing sea ice driven in part by changes in heat flux from the North Pacific. Paleoclimate reconstructions have improved our knowledge of Alaska’s hydroclimate, but no studies have examined Holocene sea ice, moisture, and ocean-atmosphere circulation in Arctic Alaska, limiting our understanding of the relationship between these phenomena in the past. We present a sedimentary diatom assemblage and diatom isotope dataset from Schrader Pond, located ~80 km from the Arctic Ocean. We interpret these new datasets alongside synthesized regional records of Holocene hydroclimate, and sea ice reduction scenarios modeled by HadCM3. The paleo data synthesis and model simulations suggest the early and middle Holocene in Arctic Alaska were characterized by less sea ice, a greater contribution of isotopically-heavy Arctic-derived moisture, and wetter climate. In the late Holocene, sea ice expanded and regional climate became drier. This climatic transition is coincident with a documented shift in North Pacific circulation involving the Aleutian Low (AL) at ~4 ka, suggesting a Holocene teleconnection between the North Pacific and Arctic. The HadCM3 simulations reveal that reduced sea ice leads to a strengthened AL shifted west, potentially increasing transport of warm North Pacific water to the Arctic through the Bering Strait. Our findings demonstrate the interconnectedness of the Arctic and North Pacific on multi-millennial timescales and are consistent with future projections of less sea ice and more precipitation in Arctic Alaska.
Intermodel comparison of Short to Medium Range Precipitation Forecasts over the Indian Sub-Continent
Authors: Saminathan Sakila , Mitra Subhasis
Published: March 2022

Reliable and accurate precipitation forecast information is needed for various disaster management and mitigation purposes. Spatio-temporal variability of forecast and uncertainty in the NWP models reduces the skill and reliability of the forecasts, hampering greater uptake for various purposes. This study aims to quantify the performance of short to medium range (1 to 7 days) precipitation forecast information from four different NWP models over the Indian sub-continent. The precipitation forecasts from these four models, namely Climate Forecast System version 2 (CFSv2), European Centre for Medium Range Weather Forecasts (ECMWF), Global Ensemble Forecast System (GEFS), and Indian Institute of Tropical Meteorology (IITM), has been assessed using different precipitation indices namely number of rainy days, accumulated precipitation, consecutive wet days, and consecutive dry days. The indices are evaluated for all the models using the evaluation metrics Heidke Skill Scores (HSS) for different seasons and basins. HSS for different indices shows that monthly HSS value was around 0.2 for the consecutive wet days while being 0.4 for the consecutive dry days showing that model's performance was good for the consecutive dry days than consecutive wet days. Results also show that the models are able to capture the number of rainy days and accumulated precipitation satisfactorily. The assessment of models and indices for monsoon and non-monsoon season showed better performance in the non-monsoon season. The evaluation of models and indices spatially over different basins in India showed that the performance was good in the central region (i.e., Narmada and Tapti basin). Overall, the forecasts from the ECMWF performed better compared to GEFS, CFSv2, and IITM. 
QBO-related Surface Air Temperature Change over the Western North Pacific in Late Winter
Authors: Park Chang-Hyun , Son Seok-Woo , Lim Yuna , Choi Jung
Published: March 2022

The impact of the quasi-biennial oscillation (QBO) on the surface air temperature in the Northern Hemisphere extratropics is investigated. It is found that the QBO, defined as 70-hPa zonal wind in the deep tropics, is negatively correlated with the surface air temperature over the western North Pacific in February and March. Cold temperature anomaly appears during the QBO westerly phase. Such relationship is likely mediated by the subtropical jet. During the QBO westerly phase, a horseshoe-shaped zonal wind anomaly forms in the upper troposphere and lower stratosphere and is connected to the equatorward shift of the Asia-Pacific jet. This equatorward jet shift is accompanied by a cyclonic circulation anomaly in the subtropical North Pacific and an anticyclonic circulation anomaly over northern Eurasia in the troposphere. The resultant temperature advection brings cold air to East Asia and the western North Pacific. This regional downward coupling in February and March, which is not sensitive to El Niño-Southern Oscillation, has become statistically significant in recent decades.
Evolution of multivariate drought hazard, vulnerability and risk in India under climate change
Authors: Venkataswamy Sahana , Mondal Arpita
Published: March 2022

Changes in climate and socio-economic conditions can induce water stress and threaten water security. India is an agriculture-dependent, densely-populated country undergoing rapid societal developments. For proper mitigation and adaptation planning in India, it is, therefore, important to assess how drought hazard, vulnerability and risk would evolve in future. Earlier studies present projected drought risk over India based on frequency analysis and/or hazard assessment alone. This study investigates future evolution of drought risk integrating vulnerability and hazard information at a country-wide scale under the mitigation (RCP2.6) and medium stabilization (RCP6.0) climate scenarios in combination with Shared Socio-economic Pathway middle-of-the-road (SSP2) socio-economic condition. A multivariate standardized drought index (MSDI) based on joint deficits of precipitation and soil moisture is chosen to characterize droughts. Drought vulnerability is assessed by the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) method, a robust multi-criteria decision-making technique, considering indicators that represent exposure, adaptive capacity and sensitivity.  Though there is a reduction in areal extent of high or very high drought hazard classes in the country by approximately 7% in future, possibly due to projected rise in precipitation, the area under high or very high drought vulnerability classes increases by 33% in the worst-case scenario. Parts of West Rajasthan, Odisha, Haryana and West Uttar Pradesh are found to be high risk under all scenarios. Bivariate choropleth plots show that future drought risk is more significantly driven by changes in vulnerability resulting from societal developments rather than climate-induced changes in drought hazard. The present study can aid the administrators, policy makers and drought managers in formulating decision support systems for effective drought management.
Exploring the influence of atmospheric forcing on Sub-Antarctic Southern Ocean hydrography and air-sea CO2 flux in coupled and ocean-only simulations
Authors: Rochner Andrea , Ford David , Sheen Katy , Watson Andrew
Published: March 2022

Various intercomparison studies have demonstrated significant disagreements and biases in the Southern Ocean’s (SO) representation in Earth System Models (ESMs). Examples include discrepancies in the strength and location of westerly wind forcing, water mass properties, or the seasonal air-sea CO2 flux phase and strength. To better understand these discrepancies, we investigate the influence of atmospheric forcing and coupling on the SO hydrodynamics based on the ocean component of the UKESM1, consisting of NEMO (ocean physics), MEDUSA (marine biogeochemistry) and CICE (sea ice). We compare a fully coupled historical UKESM1 run and an ocean-only run initialised on 01/01/1980 from the coupled run but forced with the ERA-Interim atmospheric reanalysis between 1980-2014. The first years after initialising the ocean-only run shows a strong loss in upper ocean buoyancy (top 1000 m), reducing the overly strong stratification present in the coupled run compared to observations. In response the horizontal circulation changes, for example the Antarctic Circumpolar Current (ACC) extends deeper and is more confined meridionally in the ocean-only run while maintaining a similar strength. Furthermore, stratification and circulation changes allow for deeper winter mixed layers in the mode water formation regions north of the ACC in the ocean-only run, better matching the observations. Thus, the representation of mode water properties improves in the ocean-only run, as well as the overall water column structure. These highlighted differences between the two runs further affect the SO’s export of water masses to the global ocean, and the local variability of biogeochemistry: for example, the seasonal cycle of air-sea CO2 flux in mode water formation regions has the opposite phase in the coupled compared to ocean-only run. Our results highlight room for diverse improvements in the representation of SO dynamics in ESMs, ultimately improving global climate projections.
Building a Low-Cost Magnetometer as a Tool for Geophysics Outreach
Authors: Bower Darcey , Paterson Greig
Published: March 2022

Geophysics is currently undergoing a recruitment crisis, with a key cause being accessibility. Introducing school pupils to geophysics by allowing them to conduct their own experiments is proposed to be a solution. However, the high costs of industry-standard equipment are prohibitive to schools. This project presents the path to creating a low-cost magnetometer system built around a microcontroller and a fluxgate sensor. The aim is for the cost of prototyping to remain under £300 (~€400).

The fluxgate magnetometers generate a square wave, the frequency of which is proportional to the magnetic field strength. This frequency is converted to voltage that can be read by an analogue to digital convertor (ADC) that is standalone or integrated into a microcontroller. The fluxgates are calibrated using a solenoid with a varying current applied is used to determine a relationship between the signal period and voltage of the fluxgate sensor and the magnetic field strength it experiences. An appropriate averaging time to measure the signal over is also chosen. The impact of the resulting resolution is considered for the system’s intended application.

School pupils will use the system to investigate the decay of a magnetic dipole source with distance. This links directly to the UK’s A-Level Physics curriculum and can be used as a learning tool to introduce concepts such a rock and palaeomagnetism. Another fluxgate sensor can be added to the system to form a magnetic gradiometer. With the implementation of additional sensors to measure external variables (e.g., temperature and tilting), log data (SD card reader, real time clock), and improvements to the physical set-up, a system capable of field surveys will be built, allowing school pupils to conduct a geophysical survey on-site.