bluuebunny/crossref_metadata_2025 huggingface dataset:
Interannual variability in Monsoon Low Level Jet and Indian summermonsoon rainfall (ISMR)
Authors: Purwar Smrati , Vasudevan Rakesh , Mohapatra Gyanendranath
Published: March 2022

The strong cross-equatorial Low Level Jet (LLJ) exists over the Indian Ocean and the South Asia is an important component in modulating the Indian Summer Monsoon Rainfall (ISMR). The interannual variation of the Monsoon LLJ (MLLJ) is examined using the interim European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-Interim), Indian Monsoon Data Assimilation and Analysis (IMDAA), and Modern-Era Retrospective Analysis for Research and Application (MERRA) reanalyses data at different pressure levels during the 40 years period (1979-2018) and its implications on ISMR is studied using 0.25°× 0.25° gridded rainfall data for same period from IMD (Indian Meteorological Department). In June, July, August and September, the analysis of MLLJ strength at different level shows that the maximum wind speed in MLLJ core region is fluctuated between the levels 850hpa to 950hpa.The maximum MLLJ strength is calculated by taking maximum of wind speed over the core region (0°N- 20°N, 40°E- 80°E) of MLLJ and for the pressure levels (1000hpa to 700hpa) for each year and the MLLJ height is defined as the vertical pressure level at which the MLLJ strength is maximum. The trend analysis of maximum MLLJ strength and MLLJ height is carried out using reanalyses data and results suggest that there is an increasing trend in maximum wind speed during ISM months for ERA and MERRAdata while decreasing trend is seen with IMDAA. Also, the MLLJ height is showing negative trend for July and September months in MERRA data. The spatial correlation analysis of MLLJ strength and height with ISMR over India is computed to analyze the impact of inter annual variations of MLLJ in ISMR.It is noted thatthe MLLJ strength for June and September months has strong positive correlation with the rainfall of these months comparedto the months of July andAugust. Results show that MLLJ (strength and height) plays an important role in modulating rainfall particularly during the onset andwithdrawal phases of Indian summer monsoon.
A Band Model of Cambium Development as a new tool of xylogenesis development
Authors: Shishov Vladimir , Tychkov Ivan , Zelenov Grigory
Published: March 2022

More than 60% of tree phytomass is concentrated in stem wood, which is the result of periodic activity of the cambium. Despite this importance, there are still few attempts to quantitatively describe cambium dynamics.

In this study, we present a state-of-the-art Band Model of Cambium Development, based on the hypothesis of the kinetic heterogeneity of the cambial zone and the connectivity of the cell structure as the forming water-conducting tissue of the coniferous tree.

The new model significantly simplifies the assessment of seasonal cell production for individual trees of studied forest stand based on the same climate signal. It allows the entire range of individual absolute variability in the forming rings of any tree in the stand to be quantified.

Due to the simplicity new approach can be applied for the most of conifer forests where the climate plays a role of limiting growth factor.
Changes in mercury volatilization flux induced by water vapor generation in soils under dynamic temperature
Authors: Kondo Monami , Tanaka Ryota , Sakamoto Yasuhide , Kawabe Yoshishige , Nakamura Kengo , Watanabe Noriaki , Komai Takeshi
Published: March 2022

With the entry into force of the Minamata Convention from 2017, anthropogenic mercury emissions into the atmosphere have been regulated, and therefore global mercury management has become an important issue. It should be noted that the amounts of anthropogenic mercury emissions and natural emissions from terrestrial sources such as soil and vegetation are almost the same based on the Global Mercury Assessment Model by UNEP (2013). Previous studies have clarified that various environmental factors such as temperature, soil porosity and water content, and pH of the water influence mercury volatilization flux from soils. In order to understand and predict transport phenomena of mercury in soils including the emission to the atmosphere, it is necessary to consider in detail not only static factors such as soil porosity but also dynamic factors such as temperature including their spatial variations.

In this study, continuous measurements of mercury volatilization flux were conducted for dynamic temperature, different soil water contents and pH-dependent dissolved mercury species. The results showed that the flux values under dynamic temperature were different from those under static temperature even at the same temperature. Additionally, changes in the flux under dynamic temperature depended on the soil water content. We have found that it is difficult to predict mercury volatilization flux under dynamic condition based on the knowledges obtained under static condition probably due to large influence of water vapor generation under dynamic temperature. It is therefore necessary to understand advection and diffusion in soils in the presence of volatilization and condensation of water and dissolved mercury for better understanding mercury flux emission from the soils.
A dataset for multi-risk analysis in the Philippines
Authors: de Ruiter Marleen , Votano Giovanni , Couasnon Anaïs
Published: March 2022

The occurence and impacts of disasters are increasing in many parts of the world. The increased complexity of disaster risk due to climate change, expected population growth and the increasing interconnectedness of disaster impacts across communities and economic sectors demonstrates the need to improve our ability to understand and model the impacts of consecutive disasters. These consecutive disasters can be described as disasters whose impacts overlap temporally and spatially while recovery from an earlier disaster is still underway. Several challenges affect our ability to account for the impacts of consecutive disasters and multi-hazard interactions, including extensive data requirements and a common focus on single-hazard risk.  

 

Incorporating spatiotemporal dynamics of hazard, exposure and vulnerability is key to understanding drivers of risks and their interactions. In this study, we focus on the Philippines and generate an extensive dataset of multi-hazard events based on observed time series of disasters. We illustrate the potential applications of our dataset with an analysis of the inter-arrival time between hazard events and their impacts. The Philippines is located along the ‘Ring of fire’ and is one of the world’s most at risk countries of natural hazards includingearthquakes, tropical cyclones, landslides, and flooding. The study is carried out for the time period 1980-2019 and at two spatial scales: national and provincial. This dataset is further analysed to document the socio-economic impacts of consecutive disasters as well as the interdependencies and dynamics between multi-hazard events. This spatially and temporally consistent dataset can be used as input for future risk modelling effort to integrate the dynamics and impacts of consecutive disasters.
Improving analytical methods for the extraction and analysis of biodegradable and non-biodegradable microplastics in the soil environment. 
Authors: Davies Grace , Lynch Iseult , Krause Stefan , Marshall Samantha , Mascelloni Massimiliano
Published: March 2022

Global plastic production reached 368 million tonnes in 2019 (Plastics Europe, 2020), with the greatest demand being for packaging. Plastic waste management in many countries is mismanaged, with ~25% of post-consumer waste globally sent to landfill in 2018, this increases the likelihood of plastic ending up in the environment, raising concerns about the impact of plastic pollution on the environment. Microplastics (particles <5mm) are emerging contaminants with high risk due to their ubiquity in the environment and the as yet unknown scale of their impact on organisms and ecosystems.

Microplastics are present in all environmental compartments, but research to date has focused on marine systems, leaving a substantial knowledge gap in understanding how microplastics behave in and impact other environments, especially terrestrial ones. Terrestrial soils provide key ecosystem services (e.g. food provision and climate regulation), however these services are threatened by soil pollution including from microplastics. Soils act as a sink for microplastics, which typically enter the soil through their widespread use in agriculture. Common entry pathways include the application of microplastic containing sewage sludge as fertiliser, and the direct application of microplastics via the polymer encapsulation of pesticides and seeds. Whilst the impacts of microplastics are not fully known, it is possible that they will compromise soil health and functions.

We urgently need to understand how microplastics of different compositions and sources affect soil ecosystems, but research progress is hindered due to the lack of standardised protocols for the identification, extraction, and analysis of microplastics in the complex soil environment. Soil is high in organic matter, meaning protocols devised for aquatic samples are not feasible because more aggressive digestion steps are required to remove soil organics.

This poster looks at the extraction and analysis of microplastics from soil samples, following a generalised framework of sieving, density separation, organic digestion, and analysis. It outlines the effectiveness of each step in the soil matrix and its applicability for both biodegradable and non-biodegradable microplastics. It compares the effect of commonly used digestion solutions (e.g. Fenton’s reagent, hydrogen peroxide) on the polymers, by using Raman spectroscopy to characterise the plastics before and after treatment, and thus to assess chemical changes arising from the sample processing. Based on these results an optimal workflow is defined as the basis for evaluating the biodegradation of microplastics in soil.
Effects of Subauroral Polarization Streams on the Equatorial Electrojet During the Geomagnetic Storm on June 1, 2013
Authors: Zhang Kedeng , Yamazaki Yosuke , Xiong Chao
Published: March 2022

In this work, the effect of disturbance dynamo electric field (DDEF) induced by subauroral polarization streams (SAPS) on the variations of the equatorial electrojet (EEJ) and its counter electrojet (CEJ) during the geomagnetic storm on June 1, 2013 is analyzed in detail for the first time. Observations from ground-based magnetometers showed that the SAPS-induced EEJ flows westward and eastward in the daytime and dawn/dusk sectors, respectively. The effects of SAPS on EEJ are mainly associated with the changes of zonal ionospheric electric field, while the changes in the ionospheric conductivity play a secondary role. By using Thermosphere Ionosphere Electrodynamic General Circulation Model simulations, the zonal electric field induced by SAPS associated with the DDEF is examined. The results of the simulations show that the DDEF has a significant impact on the EEJ variability. The daytime westward EEJ at the dip equator is mainly driven by disturbance zonal wind, with secondary contributions from disturbance meridional wind. A similar mechanism can be observed in the dawn/dusk sector when the eastward EEJ is produced; however, it has a much weaker intensity than that during the daytime.
Understanding and quantifying potential drivers of compound extremes: A complex networks based on multiscale entropy approach
Authors: Guntu Ravi Kumar , Merz Bruno , Agarwal Ankit
Published: March 2022

The compound dry and hot event (CDHE) has been paying attention in recent decades due to its disastrous impacts on diverse sectors. The teleconnections between dry conditions and large-scale circulation patterns have been widely studied at different spatial and temporal scales. However, studies investigating the links between large-scale circulation patterns and CDHE using a multiscale approach is missing. Quantifying the external forcing of compound dry and hot extremes (CDHE) is tedious and demands in-depth understanding.  We introduce a novel method by integrating wavelets, entropy and complex networks to quantify the potential drivers linked with CDHE. Firstly, a standardized dry and hot Index (SDHI) is developed to model the combined effect of precipitation and temperature using a copula approach. Second, the SDHI and Sea Surface Temperature (SST) is decomposed using wavelets to comprehend multiscale dynamical processes across time scales. Next, entropy is employed to quantify the similarity between SDHI and SST across multiple timescales. The proposed method uses the wavelet energy distribution of CDHI at different time scales and compares it with the wavelet energy distribution of SST to quantify the similarity. From similarity, complex networks is constructed to bridge the links between CDHE and circulation patterns. To investigate the efficiency and reliability, the proposed method is explored to improve the understanding and quantify the potential drivers of CDHE at a regional scale during the summer monsoon in India.  The results show that an integrated approach combining wavelets, entropy and complex networks offers a fresh perspective in analyzing the teleconnections between the compound extremes and large scale circulation patterns.
Automatic detection and classification of seismic signals of the Popocatepetl volcano, Mexico, using machine learning methods.
Authors: Bernal Manzanilla Karina , Calò Marco
Published: March 2022

Many studies highlight the benefits of using machine learning algorithms for the classification of volcano-seismic signals. However, when it comes to their widespread application, volcano observatories and researchers face two important challenges. i) The performance of these models highly depends on the size of the training set, where large amounts of labeled signals (thousands and sometimes even hundreds of thousands) are needed to get sufficient accuracy. ii) Most of them use data recorded by a single station and from only one component. This “master” station is generally one of the closest to the crater and, in volcanoes, it is common to face technical difficulties that interrupt the continuous recording, especially during periods of increased activity.

This strongly limits the possibility of applying machine learning approaches for efficient monitoring of volcanoes, especially during unrest periods.

Here, we show a simple method that addresses these difficulties using the information provided by the entire network of stations operating at Popocatepetl volcano (about 18 stations among permanent and temporal) and using all the components. Initially, we used a mid-size catalog of 507 single-channel labeled events recorded between 2019 and 2020. Later, to increase the size of our dataset and exploit the information provided by different channels, we added the signals of the three components of all the events, as well as signals of selected events recorded at different stations. This enlarged training set comprises 1725 signals of six classes: 345 noise, 324 explosions, 321 long periods (LP), 306 volcano-tectonics (VT), 264 tremors, and 165 regionals. To characterize the data, we used a previously proposed set of 102 features that describe the shape, statistics, and entropy of the signals. Then we applied two classification algorithms, random forest and support vector machines, to both our datasets. Our results show that the model of the enlarged dataset increases the overall accuracy by over 8% compared with the one produced using one station and only one component, with the additional benefit of guarantying continuous monitoring even when the “master” station is not working.
Evolution of the Permian carbonate platform on Gondwana shelf, Pakistan: sedimentological and biostratigraphic approach
Authors: Wadood Bilal , Li Hong , Khan Suleman
Published: March 2022

The Permian time is characterized by various geodynamic and biotic events. The rifting of Gondwana and the formation of the super-continent Pangea are the most important events. The cessation of major Gondwana rifting and thermal cooling has subsequently resulted in the development of marine Tethyan settings at the margin of the northwestern Indian Plate. Based on detailed outcrop-based lithostratigraphical investigations, a total of three formations have been distinguished. The presence of diagnostic foraminifer’s species able to assign Wordian, Capitanian-Wuchiapingian, and Late Wuchiapingian to Changhsingian ages to these rock units respectively. The detailed biostratigraphic and sedimentological analyses of the upper Permian units of northern Pakistan divulged three phases of the carbonate platform development. Initially, the early Permian pure clastic Gondwana deposits were replaced by the Tethyan setting during the middle Permian (Wordian) time whereby the wave-dominated delta was established as the sea-level rises. However, such deltaic deposits were gradually evolved into a pure carbonate system during the Capitanian time in response to gradual transgression. The Capitanian and Wuchiapingian times show the development of a diverse shallow carbonate platform along the northwestern Indian Plate. The late Permian global regression has significantly disturbed the carbonate factory and subsequently developed river-dominated deltaic deposits of carbonate and clastic mixed system. Such a mixed system was again evolved in a carbonate platform during the Early Triassic.
Characterisation and model representation of the diurnal cycle of precipitation over the Maritime Continent
Authors: Mustafa Jack , Matthews Adrian , Hall Rob , Heywood Karen , do Valle Chagas Azaneu Marina
Published: March 2022

The diurnal cycle is one of the major modes of weather variability over the islands and coastal seas of the Maritime Continent. As observed in gridded data from the GPM satellite, the mean diurnal cycle of precipitation over land comprises a relatively rapid increase in rainfall rate through the afternoon followed by a more gradual decrease in intensity through the evening and night. Characterisation of this cycle using a small number of independently intuitive parameters helps in the assessment of model performance, and a best-fit waveform approach is often favoured for its conversion from discrete data to a continuous approximation. The phase of the peak of the best-fit first diurnal harmonic (a pure sine wave of 24-hour period) is systematically later over land than the observed time of peak precipitation by the order of one to three hours. Fitting of the mean diurnal cycle of precipitation using a skew-permitting waveform is trialled to capture its characteristics more accurately. A positive skewness, indicating a sharp rise and gradual decrease, is observed across most land area while skewness over the coastal seas is regionally dependent. Positive skewness over land displaces the best-fit peak to earlier time than the first diurnal harmonic peak, resulting in improved alignment between the observed peak and the best-fit peak, generally within one hour.

 

The skew-permitting approach to characterisation is further applied to data from regional hindcast model runs to assess model skill at capturing the diurnal cycle. It suggests reasonable skill over mountainous land area where diurnal deep convection tends to initiate, but poor skill over land away from such convection centres. The skewness parameter exposes poor skill over the coastal seas; immediately offshore southwest of Sumatra the amplitude and phase parameters from the model align well with observed values, however model skewness infers a gradual intensification of mean precipitation up to the peak while observations indicate a rapid intensification in this area. These findings will contribute to our understanding of the deficiencies of rainfall propagation mechanisms in models.
Anticipating future ice-dammed lakes across High Mountain Asia
Authors: Compagno Loris , Huss Matthias , Zekollari Harry , Miles Evan , Farinotti Daniel
Published: March 2022

Over recent decades, a significant increase in the amount and the size of glacier lakes has been observed. These lakes enhance glacier mass loss but also present societal hazard as they may retain large volumes of water. When large lakes drain, the downstream valleys can severely be impacted by the resulting glacial lake outburst floods (GLOFs), potentially leading to infrastructural damage and ecological impacts. Most studies assessing the future evolution and potential hazards from glacial lakes focus on proglacial lakes, i.e. lakes that are dammed by either moraines or bedrock. Albeit typically more hazardous, ice-dammed lakes including supraglacial lake are generally neglected in such assessments. 

Here, we assess for the first time the formation and development of potential ice-dammed lakes for all glaciers in High Mountain Asia. To do so, we model the geometry of each glacier by linking past digital elevation models to outputs of the combined glacier mass balance, ice flow and debris evolution model GloGEMflow. We identify potential ice-dammed lakes in depressions at the surface and margins of glaciers, and model their geometrical evolution by accounting for the enhanced melt caused by the lakes’ presence. The model is calibrated and evaluated with independent datasets. 

To analyze the ice-dammed lakes’ sensitivity to climate change, we model the evolution of glaciers and their ice-dammed lakes under different Shared Socioeconomic Pathways (SSPs). Our results indicate that the total number of potential ice-dammed lakes will first increase through time, and then diminish as glaciers shrink, reducing confining barriers. Compared to 2000, a moderate warming scenario (SSP126) anticipates approx. 42% more lakes by 2050, whilst in a strong warming scenario (SSP585), the increase is of ~46%. By the end of this century, the number of ice-dammed lakes will diminish compared to the 2050 peak by approx. 16%  (SSP126) and ~42% (SSP585) due to glacier shrinkage. The same pattern is also expected for the lakes’ volume evolution, which is expected to increase compared to 2000 between ~79% (SSP119) and ~87% (SSP585) by 2050, for then diminish by about 8% by the end of the century for SSP585 compared to 2050.  Finally, by investigating the largest ice-dammed lakes, we highlight regions that could be of particular relevance when aiming at anticipating future GLOFs from ice-dammed lakes.
Testing drones and computer vision for acquiring glacier melt observations
Authors: Cremona Aaron , Landmann Johannes , Sold Leo , Borner Joël , Farinotti Daniel
Published: March 2022

Climate change is affecting glaciers worldwide, leading to unprecedented melt rates. In this context, establishing systems that provide near-real-time glacier information can be of high interest. However, the effort for acquiring real-time, in situ glacier observations is large.

In a previous study, we investigated the potential for automated acquisition of real-time mass balance readings by using optical cameras installed in-situ and computer vision techniques. The setup proved to be useful for obtaining melt rates with a temporal resolution of 20 minutes. However, it is not feasible to cover an extensive portion of a glacier with such a setup.

In our contribution, we present a method to acquire glacier mass balance readings with a custom drone equipped with a camera. The principle is to acquire images of a color-coded stake, from which surface mass balance can be determined via the glaciological method. To autonomously approach and read the stake, we exploit a combination of computer vision techniques and geometrical triangulation.  The results of off-glacier test flights, as well as four flights on Rhonegletscher, Switzerland, prove that the system is successful in detecting the stake in the videos captured by the drone. The determined stake position has uncertainties of 2.4 - 4.6 m, thus being sufficient to safely approach the stake. We investigate the main factors influencing the performance of the method in more detail, and discuss potential future developments of the system.
Distribution and characteristics of microplastics and phthalate esters from a freshwater lake system in Lesser Himalayas
Authors: Kumar Ajay , Behera Diptimayee , Bhattacharya Sharmila , Mishra Praveen Kumar , Yadav Ankit , Ambili Anoop
Published: March 2022

The occurrence, distribution, characterization and quantification of microplastics (MPs) and phthalic acid esters (PAEs) from the freshwater aquatic environment are not thoroughly explored in the Indian Himalayas despite concern over their adverse effects on human health and ecosystem. In this study, we have investigated the presence of MPs and PAEs in an aquatic system from Indian subcontinent. The MPs were detected in all water and sediment samples with abundances ranging from 02–64 particles/L and 15–632 particles/kg dw, respectively. The abundance of MPs, dominated by polyethylene and polystyrene, with the majority being fibres and fragments indicated that they were derived from plastic paints, boats or synthetic products. The concentrations of PAEs in the surface sediment samples varied from 06-357 ng/g dw. The most abundant PAEs in the sediments were dibutyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP), since they were present in all the samples collected from the lake basin. The relatively higher abundances of MPs and higher concentrations of PAEs were generally found in the vicinity of areas impacted by anthropogenic activities. A clear correlation between the abundance of microplastics and PAEs concentration was observed suggesting that they are closely attributed to a single source. This study also provides an alternative approach to utilize the chemical additives in plastics as markers to trace the presence and distribution of MPs in the aquatic environment.
Effects of sediment clustering on flow resistance in steep coarse-bed streams
Authors: Yadav Anshul , Sen Sumit
Published: March 2022

The flow velocity and discharge estimation are important in fluvial geomorphology and other wide variety of scientific purposes in river research applications. However, in steep coarse-bed streams dominated by large sediments and irregular channel beds, the conventional equations fail to consider the additional losses, leading to the overestimation of flow velocity. In such cases, the science of flow resistance, particularly during low relative submergence (y/D84), and active transport conditions, needs to be revisited. Since the poorly sorted sediments on the channel bed also increases the resistance in the flow (Yadav et al., 2021). This work examined the effects of geometric standard deviation (σg) of the bed material on flow resistance in steep streams using the dataset reported in the literature and conventional flow resistance equations. The flow resistance estimates in poorly sorted sediments were observed to be unreliable for the non-uniformity () range 7.5-10 for all the equations, however relatively better flow velocity estimates were observed for σg greater than 10. This distinct response of flow resistance equations for σg ranging between 7 to 10 was probably due to additional losses occurring due to armouring and formation of sediment clusters and reticulate structures in this subset of the data. The dimensionless shear stress (τ*) exerted on the channel bed for the dataset with σg between 7.5 to 10 was in agreement to develop sediment clusters as suggested by various researchers. Furthermore, when the geometric standard deviation exceeds 10, the unbiased flow velocity estimates using the conventional flow resistance equations indicate the reduced resistance in the flow field. This behaviour may be attributed to the smoothing of bed or change in bed conditions either due to disintegration of bedforms and sediment clusters at higher discharge or structural instability. 

Keywords- Flow resistance, sediment sorting, non-uniformity, sediment clusters, armouring, shear stress

 

Yadav, A., Sen, S., Mao, L., & SchwanghartW. (2021), Evaluation of flow resistance equations for high gradient rivers using geometric standard deviation of bed material, Journal of Hydrology (accepted)
Sea surface temperature impact on Madden-Julian Oscillation convection in the Met Office coupled and atmosphere-only forecast models
Authors: Karlowska Eliza , Matthews Adrian , Webber Benjamin , Graham Tim , Xavier Prince
Published: March 2022

Forecasting the Madden-Julian Oscillation (MJO) is challenging for many numerical weather prediction (NWP) systems and climate models. Models tend to simulate slower MJO propagation than in observations, impacting other weather and climate patterns across the world through its teleconnections. Observations show that sea surface temperatures (SST), and subsequently sea surface fluxes influence MJO convection in the tropics. Coupled ocean-atmosphere models, which dynamically predict SST, tend to perform better in forecasting the MJO than atmosphere-only models that use persisted SST. Lower resolution coupled climate models are routinely used by forecasting centres, however, there are only a few operational weather forecasts utilising high resolution coupled NWP systems. The Met Office has developed a coupled NWP system running in near real-time since May 2016, alongside their operational, atmosphere-only NWP system. Comparison between the models using the Real-time Multivariate MJO index reveals that both are similarly skillful within 7 and 10 forecast days for operational and coupled models, respectively. The coupled model produces faster MJO propagation than the operational model. Consistent with this faster propagation, coupled model forecasts initiated during active MJO convection over the Indian Ocean (RMM phase 1), show enhanced convection by lead day 7 in the Sulawesi-Banda Sea region located ahead (to the east) of the convective envelope. Warm SST anomalies of order 0.1°C in that region are simulated in the coupled model composites from lead day 1, consistent with observations. When the coupled model is initialised with active MJO convection over the Maritime Continent (RMM phase 4), the model suppresses convection faster in the equatorial Indian Ocean region, which is behind (to the west) of the MJO convection. Cold SST anomalies are created in the coupled model from lead day 1 in that region, stronger than observations suggest and leading to excessive suppression of convection in the coupled model here. We explain the differences between the coupled and atmosphere-only simulations through a combination of upwelling diagnostics, analysis of moisture budget terms and targeted numerical experiments for SST-convection feedback.
A Paleozoic accretion history: Igneous and detrital zircon signatures of the Kulutingwak and Danish River formations in the Yelverton Inlet-Phillips Inlet region, Ellesmere Island, Nunavut, Canada
Authors: Koch Megan , McClelland William C. , Gilotti Jane A. , Kośmińska Karolina , Faehnrich Karol , Strauss Justin V.
Published: March 2022

The Ordovician Kulutingwak Formation of Ellesmere Island, Nunavut, Canada is an enigmatic assemblage that occurs exclusively in fault-bounded panels in a critical 30 kilometer transect between the crystalline basement of the exotic Pearya terrane and clastic rocks on the Laurentian margin. The Pearya terrane is hypothesized to have accreted to the Laurentian margin during late Silurian to Devonian time. The Kulutingwak Formation includes metasedimentary, volcanic, and volcaniclastic rocks with local carbonate olistoliths and serpentinite-bearing lithologies that collectively represent a subduction-related assemblage formed in an accretionary prism. As such, this formation has been cited as evidence of an arc-continent collision, giving these rocks a significant role in shaping tectonic models for the accretion of the Pearya terrane, and subsequently, the assembly of the circum-Arctic region during the Paleozoic. Igneous and detrital zircon U-Pb and Lu-Hf data from 11 samples collected from the Kulutingwak and Silurian Danish River formations between the Petersen Bay fault zone (PBFZ) and the Emma Fiord fault zone (EFFZ) record a dynamic early Paleozoic tectonic setting at the northern Laurentian margin. Detrital zircon spectra from the Kulutingwak samples adjacent to the PBFZ show major age peaks at ca. 960 Ma that record affinity with the Pearya terrane basement, as well as peaks at ca. 1820 Ma and 2700 Ma that suggest a Laurentian margin source. Additionally, two samples record the presence of a 502–508 Ma source which is not well-documented in this region. Kulutingwak Formation volcaniclastic rocks further to the south in the EFFZ yield U-Pb zircon ages 456–465 Ma and εHf(t) signatures of -5 to +10, implying association with volcaniclastic rocks of the newly redefined Ordovician Fire Bay Formation, a dismembered arc fragment equivalent to Ordovician arc-related rocks connected with the Pearya terrane. The data demonstrate that there are at least two distinctive components within the currently defined Kulutingwak Formation: one that records combined provenance signatures from the Pearya terrane and the Laurentian margin in the Paleozoic and another that signals the presence of an Ordovician arc at ca. 455–470 Ma. U-Pb detrital zircon data collected from the Silurian Danish River Formation in this region demonstrate affinity with the Pearya terrane, with a major age peak at ca. 960 Ma. Composite signatures of ca. 960, 1820, and 2700 Ma in the Kulutingwak Formation suggest that the Pearya terrane had reached the Laurentian margin in Late Ordovician to Silurian time.
Analysis and proposal of empirical magnitude scaling relationships for the seismic potential of earthquakes in Central America: its application for seismic hazard studies
Authors: Arroyo Solórzano Mario , Benito Belén , Alvarado Guillermo , Climent Álvaro
Published: March 2022

Central America is a seismically active region where five tectonic plates interact (North America, Caribbean, Coco, Nazca, and South America) in a subduction zone with transform faults and near to triple points. This complex tectonic setting makes the estimation of the seismic potential (maximum magnitude) a very important task. There are a series of empirical formulas and diagrams by means of which the seismic potential of faults can be estimated from rupture earthquake geometry parameters. In this study, some of these formulas were applied to approximate the magnitude of earthquakes occurred in Central America, comparing the estimated magnitudes with those observed instrumentally. This has been accomplished based on the most complete data set of relevant and better characterized earthquakes generated by faults in the region. The data set consists in a compilation of the seismic events and its relatively well-established rupture parameters (length, width, area, slip, magnitude) and characteristics (location, faults, or possible associated faults, as well as localized aftershocks). The slip rate was incorporated, when available, but considering the current lack of information and, in some cases, the high uncertainty in its estimation, the use of other simpler rupture parameters is more practical and applicable for the region. Based on this, we identified which of the current available formulas developed worldwide, estimate magnitudes in a better way for the Central American seismotectonic context. The preliminary results show a better fit with the instrumental data, when the empirical equations were used with the segmented fault length. These outcomes were specifically validated for lengths between 10 and 30 km, in which the database presents good information coverage. We found that some empirical relationships fit quite well the observed data, including the classical Wells & Coppersmith (1994) equations. Finally, according to our data set compilation, we will try to propose a new empirical specific earthquake scaling relationship for Central America to be included in future seismic hazard studies. Is recommended, when possible, complement these approaches with more detailed historical seismicity review and paleoseismological, geodetic and neotectonic studies, to determine more precisely and realistically the fault’s maximum magnitude. Also, we suggest make estimates of the magnitude using the maximum and the segmented fault length and differentiating between ruptures at depth in the seismogenic zone (smaller) and ruptures in surface (larger). This approach is relevant due to the selection of an earthquake scaling relationships for a specific region is typically an abbreviated component of seismic-hazard analysis, being an important issue for the definition of source models which are one of the main inputs in the hazard estimation.
Sea ice thickness and production in Weddell Sea polynyas
Authors: Zhou Lu , Heuzé Céline , Mohrmann Martin
Published: March 2022

Open-ocean and coastal polynyas, the result of high-latitude atmosphere-ocean circulation interannual variability, alter the local air-ocean heat exchange and sea ice production. Yet, the role of the ocean, especially its thermal flux, is rarely discussed. Here we examine the surface heat budget and sea ice changes during open-ocean and coastal polynya events in the Weddell Sea using satellite retrievals, in-situ observations, and the Japanese 55-year Reanalysis (JRA55). We find that the oceanic heat flux amounts to about 57.5±4 and 39±3 W/m2 within the 2016 and 2017 polynyas events, respectively; including these values in sea ice thickness. parameterizations significantly reduced their biases. Moreover, we compare sea ice mass productions within coastal and open-ocean polynyas using three methods. The results suggest that more ice production, albeit thinner ice thickness, occurs within the open-ocean than the coastal polynya. Finally, we find that wind and air temperature directly play a crucial role in controlling sea ice production in open-ocean polynyas, and undirectly via their impact on the polynya extent for coastal polynyas. The presence of wide open-ocean polynya does appear to reduce this influences on the ice production within the coastal polynya.
The potential of a hybrid framework including data driven approaches for hydrological forecasting
Authors: Hauswirth Sandra Margrit , Bierkens Marc F.P. , Beijk Vincent , Wanders Niko
Published: March 2022

Ensemble hydrological forecasts are important for operational water management and near future planning, even more so in times of increased extreme events such as floods and droughts. Especially the latter requires a planning horizon of several weeks to months to optimize water availability. Having a flexible forecasting framework that can deliver this information in a fast and computational efficient manner is critical. In this study we are exploring a new hybrid framework, combining machine learning models with seasonal (re)forecasting information, in a hindcasting experiment to evaluate the potential of data driven approaches for seasonal forecasting purposes.

We focussed on 5 different ML methods, which are used to predict discharge and surface water levels of various stations at a national scale (the Netherlands). Input from the European Flood Awareness System and SEAS5 serve as boundary conditions. The ensemble hydrological hindcasts were then evaluated against climatological baseline hindcast with commonly used scores such as anomaly correlation coefficient (ACC), brier skill score (BSS) and continuously ranked probability score (CRPS).

We observed consistently skilful predictions for the first lead months throughout the year for all station and model combinations. Early spring and summer months show increased skill up to several months as a result of snow dynamics that were captured. Furthermore, we show that the choice of ML model only has a limited impact on the overall forecast performance.

With our study we show that a hybrid framework is able to bring location specific skilful seasonal forecast information with global seasonal forecast inputs. At the same time our hybrid approach is flexible and fast, and as such a hybrid framework could easily be adapted to make it even more interesting to water managers and their needs.
Effects of Datum Definition on Estimation of GNSS Vertical Velocities
Authors: Erkoç Muharrem Hilmi , Doğan Uğur
Published: March 2022

The aim of this study is to study the effects of datum definition on the estimation of vertical velocities at the continuous GNSS stations and campaign GNSS sites. The observations have been analyzed to measure the accuracy of vertical deformations derived from GPS stations depending on the definition datum of the geodetic network.

This investigation was carried out six campaign GNSS sites and twenty-one continuous GNSS stations operated by the National Permanent Network in Turkey (TUSAGA-Active) in the coastal regions of Turkey during the period 2001-2018. The GNSS observations were processed in the ITRF2014 reference frame using Bernese v5.2 software with different approaches based on four International GNSS Service (IGS) reference stations, which are thought to be less affected by tectonic movements.

The results show that the sensitivity of GNSS vertical velocities depends on the geometrical distribution of the reference stations and on the chosen set of reference stations that define the datum of the geodetic network. Moreover, the accuracy from the number of reference stations is one to three is less good than four or more reference stations, and the vertical velocities of our solution derived from four reference stations agree with those of the IGS solution.
High-temperature melting of different crustal levels in the inner zone of the Emeishan large igneous province
Authors: Zhang ZeZhong , Qin Jiangfeng , Lai Shaocong , Long Xiaoping , Ju Yinjuan , Wang Xingying , Zhu Yu , Zhang Fangyi
Published: March 2022

Late-Permian intermediate-acid magmatic rocks in the Panxi region, inner zone of the Emeishan large igneous province (ELIP) is of great significance for deepening the magmatic process, crustal structure evolution and metal element mineralization under the background of mantle plume.In this contribution, we report contemporaneous (~259Ma) ferrosyenite and granite in the inner zone of the ELIP, and their chronological and geochemical data suggest simultaneous crustal melting at different depths. The ferrosyenites display moderate SiO2, high Fe2O3T and alkaline contents. In combination with their positive zircon εHf(t) values (+1.5 to +12.9), we propose that the ferrosyenites were formed by high temperature melting of Fe-rich refractory juvenile lower crust at H2O-poor condition, which was induced by underplating of the high-temperature mantle plume. Rhyolite–MELTS modelling results show that ~7% melting of ferrodiorite-like source at ~1120 ℃ and 8 kbar can produce similar compositions with least evolved ferrosyenite under a relatively dry condition. The granites have high SiO2 contents and 10000*Ga/Al ratios, indicating the affinity to A-type granites. Their evolved zircon εHf(t) values (-8.1 to -0.6) indicate an evolved crustal source region. Rcrust modeling indicates that ~9% partial melting of ancient granodiorite-like crustal material under low pressure condition (4 kbar) can produce the observed granitic compositions. Considering the close spatial and temporal relationship between ferrosyenites and A-type granites, we highlight the significant impact on crustal magma response to the high-temperature mantle plume event in the inner zone of ELIP.
Organic matter distribution from the biomass to the soil in grassland, forest, and mixed ecosystem.
Authors: Baidya Disha , Roy Biswajit , Sanyal Prasanta
Published: March 2022

Soil organic matter (SOM) is made up of different components that are contributed by plant residues and living microbial biomass. The quantitative estimation of the above-ground biomass is mostly done using the molecular proxies (n-alkane) and δ13C values of SOM. However, the estimations can be site-specific and can vary depending on the contribution from the C3 and C4 plants. In a need to understand the transfer of biomass signals from the vegetation to soil, sampling sites (1mX1m) were chosen which comprises a pure grassland (C4), forest land (C3), and a mixed vegetation ecosystem from the lower-Gangetic floodplain. The  δ13C values of the above-ground biomass in grassland, forestland, and mixed ecosystem show a variation of 4‰, 7‰, and 20‰, respectively. In the associated soil, however, the incorporation of organic matter from the vegetation was not straightforward and showed a variation between +1‰ and -8‰ in three different sites. The values were 13C-enriched in soil underlying the Grassland and depleted in forest soils. The n-alkane molecular proxies in the soil such as CPI, ACL, show a decrease (about 50%) and increase in LMW/HMW concentrations in values among different sites. The decrease in molecular proxies was evident due to differences in organic matter contribution from different species. In C3 forest, the difference in degradation from different components of trees (twigs, leaves, flowers, fruits) reduces the molecular proxies and also the  δ13C values in the soil. On the other hand, grasses acting as a whole, impart limited modification during incorporation into the soil. 
Surface reactions can alter both perceived and actual composition of atmospheric Hg(II)
Authors: Khalizov Alexei , Mao Na
Published: March 2022

Mercury is a persistent and bioaccumulative environmental pollutant, entering the atmosphere mostly in elemental form and leaving in a variety of oxidized forms. However, current detection methods distinguish only three operationally defined forms: elemental, gaseous oxidized, and particulate mercury. The knowledge of molecular speciation is limited and comes mostly from computational studies, hindering our understanding of atmospheric mercury chemistry and global cycling. Achieving molecular speciation of oxidized mercury (Hg(II)) in atmospheric measurements is a major challenge because of its extremely low abundance, requiring pre-concentration on adsorbents. There is a concern that the speciation of adsorbed Hg(II) can be altered in exchange reactions with itself and with co-adsorbed atmospheric chemicals. Here we present the results of our experimental investigation of gas-surface reactions and exchange reactions involving Hg(II) and several other chemical species. These reactions were studied in aqueous solutions and on surfaces, and the products were analyzed at a molecular level in gaseous, dissolved, and solid forms. Molecular-level detection was made possible by using chemical ionization and electrospray ionization mass spectrometries, which provided sufficiently high sensitivity for direct detection of Hg(II) in laboratory experiments, avoiding the pre-concentration step. In all cases, we observed binding of gaseous Hg(II) to surfaces, followed by rapid formation of exchange products, some of which could be readily volatilized back into gas phase. We propose that a similar exchange may occur both on the surfaces of aerosols in the atmosphere and on adsorbents during sample collection, scrambling the actual and perceived speciation of atmospheric Hg(II).