bluuebunny/crossref_metadata_2025 huggingface dataset:
A probabilistic framework for quantifying the role of anthropogenic climateforcing in marine-terminating glacier retreats
Authors: Christian John Erich , Robel Alexander , Catania Ginny , Verjans Vincent , Rashed Ziad
Published: February 2023

Many marine-terminating outlet glaciers have retreated rapidly in recent decades, but these changes have not been formally attributed to anthropogenic climate change. A key challenge for such an attribution assessment is that if glacier termini are sufficiently perturbed from bathymetric highs, ice-dynamic feedbacks can cause rapid retreat even without further climate forcing. In the presence of internal climate variability, attribution thus depends on understanding whether (or how frequently) these rapid retreats could be triggered by climatic noise alone.We present simulations with idealized glaciers to analyze glacier variability in the presence of topographic thresholds, and to demonstrate a framework for attribution. We find that when termini are positioned near bed peaks in a noisy climate, rapid retreat is a stochastic phenomenon. We therefore assess the likelihood of rapid retreat, using ensembles of many simulations with independent realizations of random climate variability. Synthetic experiments show that century-scale climate trends substantially increase the likelihood of retreat. The strength of this effect is related to the timescales over which ice dynamics integrate forcing, implying that the time of onset of anthropogenic forcing is a key factor to constrain for attribution studies. We close by discussing broader considerations for framing attribution studies on marine-terminating glacier retreat, and ongoing work towards applying this framework to glaciers in Greenland.
Effect of seawater intrusion on human health risk and toxicity of disinfection by-products
Authors: Parveen Naseeba , Goel Sudha
Published: February 2023

Around the world, coastal groundwater is increasingly subject to seawater intrusion (SWI). The quality and characteristics of such waters differ from those of surface and groundwater. In the current study, trihalomethane (THM) formation under varying levels of SWI, its human health risks, and toxicity were evaluated. Various levels of SWI were simulated by mixing deionized water synthetic seawater (SSW) by varying seawater volumes from 0% to 3%. Chlorination of these samples was carried out as per uniform formation condition (UFC). Chlorine demand increased with increasing SWI.  THM concentration increased from 12.64 μg/L to 105.34 μg/L after 24 h and to 115.8 μg/L after 48 h for an increase from 0% to 3% volume of seawater. Human health risks due to THMs were determined using probabilistic risk assessment models considering ingestion, dermal contact, and inhalation as three exposure routes. Risk assessment was carried out using 1,00,000 iterations of Monte Carlo simulations. Total cancer risk increased 4 times for an increase of SWI from 0% to 0.25%. Further, the toxicity of THMs to mammalian cells due to increasing degrees of SWI was calculated. For this, the lethal concentration that reduced the Chinese hamster ovary (CHO) cell density by 50% (LC50) by all four THMs reported in the literature was considered. The highest total toxicity value of 1.07 × 10-04 was observed at SWI = 1% by volume. In general, an increase in SWI of up to 1% resulted in maximum health risk and toxicity. The results of the current study are useful for coastal water utilities and treatment plants to reduce human health risks due to disinfection by-products.
Identifying Sub-environments in a Tidal Flat: An MDS Approach
Authors: Roy Ankur , Mukerji Tapan , Chakrabarti Amitabha
Published: February 2023

Ripple marks formed in different sub-environments of a tidal flat are considered helpful in distinguishing such sub-environments from one another owing to the predominance of specific agencies that generate and stabilize these ripples. For example, ripple stabilized in tidal channels are dominated by tidal currents and those in estuarine settings are both wave and current dominated. In order to evaluate the possibility of using ripple morphology in distinguishing between such sub-environments, data on ripple index (RI) from an estuary and tidal channels were analyzed. These data were collected from the east coast of India that provides examples of open-coast tidal flats at Chandipur and 50 km north-east at Digha. It was found that they have overlapping morphological patterns as delineated from RI vs. the percentage fraction for each case of estuarine and tidal channels. So, while RI can broadly define environments, e.g., aeolian and water borne ripples, when it comes to separating wave from current ripples, a fair overlap is seen in tidal flat regions. On the other hand, grain-size study alone is insufficient for the purpose of delineating differences between such sub-environments. This is because it is seen in our analyses that while most estuarine sediments are finer than 3 on the Φ-scale and tidal channel sediments are coarser, much better sorted as well as mostly positively skewed, these values overlap such that a clear distinction cannot be achieved. Therefore, in order to distinguish between such sub-environments, we took into account both grain-size parameters associated with ripple marks and the corresponding RI values. A relative “distance” was calculated between pairs of samples based on RI, mean, sorting, skewness and kurtosis. In other words, this “distance” is a way to determine how similar two samples are in terms of their respective RI and grain-size parameters. A dissimilarity matrix was constructed which, in turn, was translated into a configuration of points in the Euclidean Space via Multidimensional Scaling (MDS). Four different “types” of measure of this “distance” were considered: Euclidean, Standard Euclidean, City Block and Minkowski (P=3). It was observed that the MDS plot based on City Block distance generated two distinct clusters of points for samples collected from estuary and tidal channels. A way forward is to employ Random Forest Analysis and test whether RI in conjunction with grain-size parameters may be used for classifying modern sediments or even rock samples representing paleo-environments as belonging to either estuarine or tidal channel setting.
Cross validation technique preference for landslide susceptibility zoning based on slope unit and machine learning workflow
Authors: Samodra Guruh , Wahyudi Erwin Eko , Susyanto Nanang
Published: February 2023

Numerous advanced techniques including machine learning models are widely used in landslide susceptibility zoning which result in very high accuracy. In some cases, very high accuracy represents an overfitting in the model, where a model adapts very well to the training data but poorly for the test or new data.  Cross Validation (CV) strategies are often employed to reduce overfitting in a machine learning model. Several cross validation techniques have been developed recently as a part of machine learning workflow.  However, the preference of choosing one cross validation method to another is still unclear in landslide susceptibility zoning. To illustrate this issue, the authors reproduce non CV, standard V-fold CV, and several spatial CV techniques using a benchmark dataset in Italy to train, validate and test an XgBoost model using 26 landslide controlling factors. The variation of RoC validation, RoC testing, and confusion matrix were used to detect the potency of model overfitting. The preference of using a CV technique for a benchmark data in Italy will be discussed further. The result is expected to provide guidance for choosing CV technique in landslide susceptibility zoning based on slope unit and machine learning workflow.
Protection of groundwater against microbial contamination
Authors: Schijven Jack , van den Berg Harold , Rutjes Saskia
Published: February 2023

A novel microbial risk analysis of groundwater as part of the Dutch guideline document for Quantitative Microbial Risk Assessment (QMRA) of drinking water consumption encompasses 1) vulnerability assessment of groundwater production sites, 2) calculating the protection zone against microbial contamination to remain below an infection risk of 1/10,000 persons/year, 3)  assessment of contamination sources within the protection zone, and 4) QMRA for identified contamination sources. Protection zones are based on a standard virus contamination scenario and may be computed using a required minimal travel time, a hydrological model that includes a first order decay term for virus inactivation and attachment, or the computational tool QMRAwell. QMRAwell is designed for unconfined and (semi)confined sandy aquifers with a forced groundwater gradient due to pumping. QMRAwell can also be used to conduct  QMRA.
Monitoring of ground subsidence in Orlando coal ash landfills using Sentinel-1 PSInSAR
Authors: shin youngnam , lee hoonyol
Published: February 2023

Globally, coal is a major mineral used in energy production, and Coal ash is produced in energy production. Coal ash pollutes the environment and causes health problems for humans. Therefore, it is important to store coal ash, most of the coal ash is stored in landfills. Landfills ground subside over time, and ground subsidence is one of the main factors in landfills stability. Therefore, it is important to understand the stability of coal ash landfills, so we would like to monitor coal ash landfills through remote sensing methods. In this study, the Stanton Energy Center, a coal-fired power plant in Orlando, Florida, in the southeastern United States, was selected as a research area. The Stanton energy center stored coal ash in a landfill next to the power plant and installed solar panels on top of the coal ash landfill in 2017. In this study, the Sentinel-1 satellite provided by the European Space Agency (ESA) was used, and ascending data was obtained between June 2018 and 2022. Digital Elevation Model (DEM) used for image processing used LIDAR DEM images with 1 m spatial resolution provided by the United States Geological Survey (USGS). PSInSAR image preprocessing used SNAP software provided by European Space Agency (ESA), and PSInSAR process used Standard Method of Persistent Scatterers (StaMPS). The PSInSAR result using Copernicus 30 DEM in the coal landfill area confirmed about 50 mm subsidence for 5  years in the LOS direction, and the PSInSAR result using Lidar DEM confirmed about 45 mm subsidence for 5 years in the LOS direction. In addition, the PSInSAR results in a stable area located near the landfill confirmed that there was little subsidence in the LOS direction for 5 years.
Space-time covariance: An effective tool to evaluate the simulated spatiotemporal patterns in land surface models
Authors: Chaney Nathaniel , Torres-Rojas Laura
Published: February 2023

Space-time patterns of surface fluxes and states have direct implications for boundary layer growth, cloud development, phenology, and runoff generation, among other processes. Emerging field-scale resolving land surface models (the terrestrial component of Earth system models), such as HydroBlocks, aim to represent this complexity by modeling the water, energy, and biogeochemical cycles at meter-km spatial scales over continental extents. Although there have been significant advances in the representation of heterogeneity in land surface modeling over the past decade, there has yet to be a concerted effort to evaluate the realism of the simulated time-evolving field-scale spatial patterns; this, in part, is due to the challenge of how to interpret the space-time fields. Empirical space-time covariance presents a unique solution; it can robustly summarize the space-time structure of a given flux or state for a given area (e.g., watershed) via a simple 2D surface (e.g., Figure 1). In this presentation, we will demonstrate how space-time covariance provides an effective and efficient approach to facilitate evaluation of the simulated spatiotemporal patterns.            As a proof of concept, the simulated spatiotemporal patterns of land surface temperature (LST) of a HydroBlocks model simulation over the central United States are evaluated using observations from satellite remote sensing (GOES-16/17). First, for each 0.25 arcdegree grid cell over the study domain, the empirical spatiotemporal covariance functions (ESTCFs) are assembled for HydroBlocks (simulation) on one side and GOES (observation) on another. For this case, each ESTCF is calculated from hourly data for clear-sky pixels during the summers of 2017-2022. The ESTCFs are then initially compared via simple metrics (e.g., RMSE). To ease understanding, a space-time parametric covariance function is then fit to each ESTCF; the comparison of the parameters (e.g., spatial correlation length) provides a richer understanding of the strengths and weaknesses of the model. The resulting analysis illustrates how space-time covariance can efficiently summarize the complex simulated spatiotemporal patterns and thus serve as a useful metric to both evaluate and inform model development to improve process representation.
A guideline for consistent water quality modeling in rural areas
Authors: Kiesel Jens , Fohrer Nicola , Wagner Paul D. , Haas Marcelo , Guse Björn
Published: February 2023

In several hydrological studies the need for consistency in hydrological modeling was highlighted. To achieve model consistency, it is required that all relevant hydrological processes are evaluated for accuracy in their spatio-temporal representation under consideration of available observations. In this study, we transfer the idea of hydrological consistency to water quality modeling. We focus on water quality modelling in rural mesoscale catchments and the interaction with agricultural production systems and their management. Based on several studies, we have developed a guideline which includes the following six challenges:Representation of rural landscape: Spatial and temporal patterns of land use and land management are critical to adequately represent water quality in models. Remote sensing and land use models are very useful resources to be exploited.
Accuracy in model structure and model parameters: The transfer of a model diagnostic analysis to water quality leads to a better understanding of how water quality variables are controlled by model structures and corresponding model parameters.
Check of multiple model output for consistency: Assessing multiple model outputs regarding their temporal, spatial and process performance using observed time series, remotely sensed spatial patterns, knowledge about transport pathways and even soft data can significantly enhance model consistency.
Joint multi-metric calibration of discharge and water quality for all magnitudes: Multi-metric calibration using performance metrics and signature measures both for discharge and water quality, such as flow and nitrate duration curve, leads to more balanced model simulations that represent all magnitudes of discharge and water quality accurately.
Scenarios and storylines for reliable land management: Scenarios and storylines should be co-developed with stakeholders in the river basin to increase realism and the acceptance of model results. They should be coherent in space and time, and provide a mix of available management options.
Consistent interpretation of impacts on water quality: The interpretation of scenarios can be supported by diagnostic tools to show the effectiveness of measures and their combinations while considering their costs and impacts on ecosystem services.
In our contribution, we give examples and further details regarding each challenge to give insights how to achieve consistency in water quality modelling.
The Dynamics of Climate Change Science and Policy in Panama: A Review
Authors: Cárdenas-Castillero Gustavo , Paton Steve , Noriega Rodrigo , Calderón Adriana
Published: February 2023

The local studies and reports indicate that the temperature of Panama has increased by approximately 1°C since the 1970s. More evidence shows a constantly rising sea level in the Guna Yala archipelago, coral bleaching on both coasts, and increasingly more frequent and extreme precipitation events throughout Panama. This study includes an analysis of over 400 scientific publications made by researchers from multiple centres and more than 20 Panamanian official reports due to Panama's mandate and duties under the international climate accords. To summarise the results, the studies were gathered according to the climate change effects by Panamanian locations and analysed posteriorly using Rstudio and ArcMAP. The results indicate a significant increase in climate change research beginning in 2007.This study identified and examined the essential findings per hydroclimatic region, showing the trends, limitations, collaborations, and international contributions. Climate change research in Panama includes some of the longest-term meteorological, hydrological, oceanographic, and biological studies in the neotropics. The most significant number of identified climate change-related studies were conducted, at least in part, in the Barro Colorado Natural Monument located in central Panama. Other frequently used sites include Metropolitan Natural Park, Soberania Park, the Panama Canal Watershed and the Caribbean coast of Colón and Bocas del Toro, primarily due to research conducted by Smithsonian Tropical Research-affiliated investigators. The tropical forests of Panama are some of the bests studied in the world; however, research has been concentrated in a relatively small number of locations and should be expanded to include additional areas to achieve a more complete and comprehensive understanding of climate change will impact Panama in the future.
Primary productivity in the northern Indian Ocean: role of nutrients stoichiometry
Authors: Rathi Ajayeta , Sahoo Deepika , Saxena Himanshu , Nazirahmed Sipai , Sudheer Athiyarath K , Singh Arvind , Kumar Sanjeev
Published: February 2023

Primary production (PP) is the basis for marine food web, which sustains life in the ocean through photosynthesis by removing carbon dioxide from the atmosphere. The rate of primary production is dependent on several factors such as light and nutrients availability, but clear mechanistic controls on this process remain elusive. Generally, primary production is sustained by a continuous supply of nutrients like nitrogen (N) and phosphorus (P). The molar ratio of ambient inorganic nutrients or stoichiometry (N:P) is supposed to have fixed values, which is Redfield ratio (6:1). However, the observed stoichiometry has been shown to considerably vary from the Redfield values and plays a significant role in affecting PP and changes in phytoplankton ecology in the ocean. The aim of this study was to examine the effects of nutrients stoichiometry (N: P) on the PP. Within this context, a series of manipulation experiments by adding nutrients in different ratios (N: P) at different concentrations level were conducted in the surface waters of the Arabian Sea and the Bay of Bengal during fall intermonsoon (Sept-Nov) 2021 using 13C tracer technique. In our results, PP showed the highest increase at N: P ~ 16:1 at all concentration levels in the Bay of Bengal. Whereas, in the Arabian sea, northern stations showed no difference in PP with changing stoichiometry but southern stations showed increase in PP due to increase in ratio at higher concentration level. 
Non-local Machine Learning-based Gravity Wave Parameterization trained on an O(1 km) Resolution Global Climate Model
Authors: Gupta Aman , Sheshadri Aditi , Mansfield Laura
Published: February 2023

Gravity waves (GW) are one of the key drivers of middle atmospheric circulation. They drive the mesospheric circulation and the QBO - the predominant mode of tropical stratospheric variability  -  and play an important role in the wintertime polar vortex variability. These waves manifest over spatial scales as small as O(10 m) to as large as O(1000 km) and thus, are often poorly resolved in global climate models on account of limited model grid resolution and grid-scale numerical dissipation. Moreover, the parameterizations used to represent the momentum forcing associated with GW are highly idealized and often not well-tuned due to limited observations. These parameterizations simplify GW representation by ignoring certain aspects of their dynamical evolution, including lateral propagation, transience, and intermittency, which results in an inaccurate model representation of their interaction with the synoptic and mean flow.

The present work focuses on creating a new, data-driven emulator for GW representation in climate models. The emulator employs an artificial neural network that learns the local and non-local gravity wave evolution by training on high-resolution reanalysis (ERA5) and ECMWF’s global 1km-resolution climate model that respectively partly and fully resolve the mesoscale portion of the atmospheric gravity wave spectrum. We test the performance of the data-driven emulators by embedding them in an intermediate-complexity climate model and assessing their momentum contribution towards driving a suite of middle atmospheric processes including the springtime disintegration of the Antarctic polar vortex, the quasi-biennial oscillation of the tropical stratospheric winds, and the sudden stratospheric warmings.
Turbidity variations in the epilimnion of a glacier-fed reservoir
Authors: Robb Daniel , Pieters Roger , Lawrence Gregory
Published: February 2023

We have been investigating the variation of turbidity in the surface waters of Carpenter Reservoir, British Columbia, Canada. This long (~50 km) and narrow (~1 km) hydroelectric reservoir receives glacially-turbid meltwater, and there is concern that this turbidity limits light availability in the reservoir and, in turn, limits biological productivity. To address these concerns and to investigate the physical processes affecting turbidity, we use a combination of field observations, numerical simulations and analytical scaling arguments.

Vertical profiles of temperature and turbidity indicate that during the summer stratified period, inflows plunge below the thermocline and travel along the bottom of the reservoir to the deep withdrawals. The load of glacial particles entering the reservoir is highest in summer. Yet, remarkably, turbidity in the epilimnion declines due to a combination of two processes: (1) thermal stratification isolates the epilimnion from plunging glacial inflows, and (2) suspended particles settle from the epilimnion to the hypolimnion. Nevertheless, profiles collected during strong winds indicate that episodic wind events can upwell turbid fluid from below the epilimnion into the surface waters. The upwelled water is then advected downstream, setting up a longitudinal turbidity gradient.

Two-dimensional numerical simulations support the notion that wind-driven upwelling in summer contributes to a small turbidity flux into the epilimnion. The simulated thermocline deflections reveal waves with two dominant periods. The first period of approximately 4 days corresponds to the fundamental internal seiche, and the second period of 1 day corresponds to direct wind-forcing by diurnal winds. Changes in turbidity along the length of the epilimnion are determined by wind-driven fluxes at the upstream end of the epilimnion, longitudinal dispersion along the length of the epilimnion and particle settling out of the epilimnion.
Tracer test for evaluating the shallow groundwater flow in a volcanic area, Taiwan
Authors: kuo Ching-Huei , Tseng Pei-Yun , Chen Yi-Ling
Published: February 2023

A tracer test, involving conservative and reactive, was conducted in a volcanic area in Northern Taiwan to evaluate shallow groundwater characteristics. The distance between injection Well #14 and monitoring Wells #2 and #6 are 236 and 682 m, respectively.  A breakthrough curve was received from both wells for conservative tracer, 2,6NDS, while the reactive one was obtained only at Well#6 indicating the existence of heterogeneity in groundwater and fracture distribution in the region.  A much fast flow between Well#14 and #6 was found as the first peak arrives at the same time with a 3 times difference in distance.  This result matches the local orientation of the formation and may show strong geology control groundwater flow of the region resulting in a preferential flow. However, a chaser influence was identified by an irregularity of breakthrough curves for both wells.
The impact of dry intrusions on midlatitude cold-air outbreak cloud transitions
Authors: Tselioudis George , Tornow Florian , Ackerman Andrew , Fridlind Ann
Published: February 2023

Cold-air outbreaks (CAOs) form marine boundary layer (MBL) clouds that undergo rapid overcast-to-broken cloud regime transitions, initiated by substantial rain. CAOs are usually accompanied by dry intrusions (DIs) that subside as free-tropospheric (FT) air into the postfrontal sector of mid-latitude storms. For an exemplary cold-air outbreak in the NW Atlantic that showed faster transitions (corresponding to reduced extents of overcast clouds) closer to the low-pressure system, we posit that varying transitions are caused by an uneven meteorological pattern imposed by the prevailing DI. We compile satellite observations, reanalysis fields, and Lagrangian large-eddy simulations (LES) translating along MERRA2-based trajectories to show that postfrontal trajectories closer to the low-pressure system are uniquely favorable to rain formation (and, thus, cloud transitions) as they show (1) weaker FT subsidence rates, (2) greater FT humidity, (3) greater MBL windspeeds, and (4) a colder MBL as well as reduced lower-tropospheric stability. We present an updated conceptual view of postfrontal cloud formation that may guide future investigations.
Sources and sinks of atmospheric nitrous acid (HONO) in the megacity of Shanghai during COVID-19
Authors: Wang Yue , Wu Dianming
Published: February 2023

The COVID-19 global pandemic has significantly affected air quality due to changes in human behavior. Gaseous nitrous acid (HONO) is a significant precursor of the hydroxyl radicals (OH), powerfully influencing atmospheric oxidization capacity and air quality. However, the impacts on the sources and sinks of HONO during COVID-19 are not well understood. Here, we observed the concentrations of HONO, nitric oxide (NO), and nitrogen dioxide (NO2) in the suburb of Shanghai during May 2020 (P1), August 2020 (P2), and April 2021 (P3) to analyze seasonal variations of HONO chemistry and also clarify how different pandemic phases influence HONO sources and sinks. The average concentration of HONO during P1, P2 and P3 showed an increasing trend (0.292 ± 0.0078、0.358 ± 0.0115, and 0.415 ± 0.0115 ppb, respectively), with direct emission from vehicles was the most essential source of the nocturnal HONO concentration (38.14%, 47.52%, and 50.95%, respectively), followed by heterogeneous conversion of NO2. The daytime HONO sources presented noticeable discrepancy among three study periods. In spring, homogeneous reaction was the primary HONO source with a mean production rate of 0.2 ppb h−1, while there was almost no unknown source (Punknown). In summer, however, the average production rate of homogeneous reaction decreased to 0.15 ppb h−1, while Punknown was up to 58% of the whole HONO production, demonstrating some strongly enhanced source(s) in the summer season. By comparing HONO budgets between different pandemic phases, the contributions of vertical and horizontal transport doubled from P1 to P3, with the average production rates increasing from 0.03 to 0.06 ppb h−1. Our results also showed that the strict lockdown measures reduced the unknown sources of HONO (P1), and correspondingly, as Shanghai implemented regular epidemic prevention and control measures, the relatively high rate of Punknown was observed during P3, making up 35% of the whole HONO production. What is more, through the strong correlation with J(HNO3) (r = 0.9) and J(NO2) (r = 0.89), it can be argued that the photolysis of nitric acid and photo-enhanced heterogeneous conversion may be a vital production pathway. The HONO photolysis was the major loss pathway, occupying approximately 85% of HONO loss during all campaigns. During noontime, the average photolysis loss rate was 1.07、2.40 and 1.86 ppb h−1, accounting for up to 96% of the HONO sinks. Dry deposition was the second important loss pathway, especially in the morning and before sunset. This study indicates remarkable seasonal variations of HONO and the effects of COVID-19, and has significant implications on controlling measures of air pollutants in megacity.
Understanding the Changes in the Post-Glacial Depositional Environments through High-resolution Geochemical Proxies in the Central Yellow Sea
Authors: Cho Jin Hyung , Kum Byung-Cheol , Jang Seok , Lee Cheolku , Lee Seunghun , Son Young Baek , Jung Seom-Kyu
Published: February 2023

Sediment cores (A10 and I06) were analyzed using a high-resolution X-ray fluorescence (XRF) core scanner to understand changes in paleo-sedimentary environments of the study area. Age dating reflects environmental changes from interglacial marine isotope stage 3 (MIS 3) through the last glacial maximum (LGM; MIS 2) to the Holocene. Three layers were identified in the seismic profiles as follows: unit 1 (thickness = ca. 5 m) in a homogeneous sedimentary phase; unit 2 formed by erosion; unit 3, which is parallel and continuous. XRF elemental proxy data indicate anomalous distributions of Ca/Fe, Ca/K, and Fe/Ti caused by organic substances that appear at several depths in the A10 core. Results show that the seafloor was exposed to air during the LGM. The I06 core shows characteristic anomalies at depths of 0.8, 1.5, and 2.5 m, which were caused by sediments supplied from surrounding rivers.
Two major near-field tsunamis (2017 and 2022) on the coast of Mexico: Observations, spectral properties and numerical modelling
Authors: Rabinovich Alexander B. , Zaytsev Oleg , Tsukanova Elizaveta , Thomson Richard E.
Published: February 2023

Two prominent near-field tsunamis impacted the nearby coasts of Mexico. The first tsunami was   generated by a major (Mw 8.2) intraplate normal-fault earthquake on 8 September 2017 in the Gulf of Tehuantepec (Chiapas, Mexico). Tsunami waves from this event were measured by a large number of high-resolution coastal tide gauges located along the coasts of California, Mexico and Central America, by three open-ocean DART stations anchored offshore from the affected region and by several distant DARTs. The second tsunami was produced by a thrust fault Mw 7.6 earthquake on 19 September 2022 within the coastal zone of Michoacán, Mexico. The 2022 tsunami was recorded by six coastal tide gauges and a single offshore DART station. All seven instruments were located within 250 km of the source. No tsunami was detected at larger distances along the coasts of North and Central America, but the tsunami signal was detected at the Hawaii and Samoa islands. All available coastal and open-ocean data were used for comprehensive analyses of these two events. Maximum trough-to-crest wave heights for the 2017 tsunami were recorded at Puerto Chiapas (351 cm), Salina Cruz (209 cm), Acapulco (160 cm) and Huatulco (137 cm), while for the 2022 tsunami they were observed at Manzanillo (172 cm) and Zihuatanejo (102 cm). For both events, the “strengths” of the recorded tsunami waves were mostly determined by distance from the source rather than by the specific resonant characteristics of individual sites. Estimates of the frequency content (“colour”) of the two tsunami events revealed that the 2017 tsunami was mostly long-period (“reddish”), with 87% of the total tsunami energy at periods >35 min, while the 2022 tsunami was short-period (“bluish”) with 91% of energy at periods <35 min. A noteworthy feature of the 2022 event was the seismically generated 7 min period seiche observed at Puerto Vallarta that began immediately after the main earthquake shock and persisted for about one hour. Numerical modelling of the events closely reproduced the coastal and offshore tsunami records and demonstrated the markedly different character of the tsunami energy radiation patterns: the 2017 tsunami spread energy widely in a semicircular pattern emanating from the source whereas  the main beam of offshore energy radiating outward from the 2022 event was directed like a “searchlight” oriented normally to the mainland coast.
Reconstructing past glacier extents in the Chilean Altiplano (18.5°-19° S)
Authors: Otto Jan-Christoph , Gallardo Matias , Sitzia Luca , Gayo Eugenia
Published: February 2023

Chronologies of glacier extents in the tropical Andes have been used to reconstruct past hydroclimate conditions during the Pleistocene and Early Holocene. Glaciers can be linked to specific climatic conditions by determining and analysing the equilibrium line altitude (ELA) at regional scales. In the tropical Andes, this approach has been used more frequently for glaciers in regions like Bolivia and Perú but little is known about past glacier extents in the Chilean part of the Central Andes. Today, glaciers in the Chilean Altiplano are very scarce, and the some few are mostly limited to single volcanic peaks (e.g., Parinacota or Acotango) covered by ice caps descending to altitudes of 5600-6000 m. Nevertheless, little attention have received moraine landforms and glacial deposits found below the modern ELA, which necessarily account for past climate conditions that favoured glacier formation and the extension of larger ice caps. Here, we present the first detailed map of glacial landforms from the Chilean Altiplano between 18.5° and 19°S. Our mapping is based on high-resolution satellite imagery and morphometric analysis implemented through a 10m Tandem-X digital elevation model supported by field observations. We reconstructed glacier extents using GIS-tools and quantified ELA locations based on the AAR method. In the study area, two, sometimes more levels of terminal moraines can be observed around the highest peaks. Glaciers have been present at all orientations with reconstructed ELA at a range between 4500-4700 m asl. ELA altitudes show significant altitudinal trends between northern and southern orientations and generally increase from West to East within our study area. Comparison of our preliminary results with existing ELA records and moraine dating available from neighbouring regions allows for a first discussion on the timing of glacier extents as well as potential implications for the hydro-climatic conditions across the Central Andes during the Pleistocene. Since ELA values from our study region are similar to those from the Bolivian Altiplano, we tentatively suggest that certain glacier extents were synchronous with major pluvial phases that resulted in glacier advances, but still, further investigation is required.
Efficacy of Halon-1301 as an age tracer - Multi-tracer evaluation in Shimabara springs
Authors: Kagabu Makoto , Kojima Shinsuke , Ishibashi Miku
Published: February 2023

For sustainable use and management of local water resources, it is essential to clarify the groundwater flow system and its scale, and one of the effective methods is to estimate the residence time. One of the methods to clarify the residence time is to use "age tracers", which are mainly used for chlorofluorocarbons (CFCs) and sulfur hexafluoride (SF6) in Japan. Since each tracer has its own advantages and disadvantages, a combination of several tracers is necessary to improve the accuracy of the estimated residence time, and the development of new age tracers is required. Overseas studies such as Beyer et al. (2014) have begun to report the application of Halon-1301 as a new age tracer, but there are no such reports in Japan. Therefore, we evaluated the applicability of the Halon-1301 method in Japan by evaluating the residence time of five of the Shimabara springs in Shimabara City, Nagasaki Prefecture, using multiple age tracers.
Glauconitization within the late Cretaceous Mahadek Formation and its stratigraphic implications.
Authors: Borgohain Dipima , Phukan Sarat , Banerjee Santanu
Published: February 2023

This study explores sedimentological and stratigraphical implications of glauconites within the upper Cretaceous Mahadek Formation exposed at the Umsohryngkew River section in Meghalaya, India. The succession is overall fining upward, with sandstone dominating the lower part and calcareous shales and limestone bands constituting the upper part of the Mahadek Formation. Glauconite occurs within the impure limestone and shale beds of the upper part of the sequence. The glauconitic section gradationally passes upward to K/Pg boundary above the Mahadek Formation. Textural, mineralogical and chemical analyses were carried out to understand the origin of the glauconite. Petrographic investigation reveals three main types of glauconites, a) pellet b) vermiform c) infilling within bioclasts. The glauconite appears dark green and the long dimension of the glauconite grain averages 200 µm. Occasionally, the glauconite grains may be as long as 500 µm. The glauconite pellets show sharp boundaries and exhibit internal cracks. The content of glauconite grain  is nearly 15-20 % of the rock volume. These are sub-rounded to rounded in shape without showing evidence of transportation. X-Ray Diffraction on air-dried samples reveals very prominent (001) basal reflection at 10.23 Å, with reflections of (020), , , (003) and (060) planes at 4.52 Å, 4.23 Å, 3.66 Å, 3.27 Å, 5.51 Å respectively. On glycolation, the (001) peak shifts from 10.23 Å to 9.95 Å, while  and (003) reflections collapse into one single peak. The peaks get narrower, more symmetrical and sharper after heating the samples at 400oC. Also, the  and (003) reflections show separations into 3.33 Å and 3.30 Å reflections respectively. The X-Ray diffraction characteristics confirm the pure nature of glauconite devoid of any interstratification. FEG-SEM imaging of glauconite grains shows a perfect lamellar structure and corroborates the X-Ray diffraction patterns of glauconites.  Further, the electron microprobe analyses data show average K2O content of the glauconite is 6.5 %, suggesting an evolved variety. The Fe2O3(total) content varies from 2.9 % to 16.8 %, with an average of 9.9 %. While the average content of Al2O3 is 20.3%. The K2O vs Fe2O3 plot (r2= 0.7) shows a strong positive correlation. The inverse correlation (r2 = 0.8) between Fe2O3 and Al2O3 suggests the replacement of Al by Fe at octahedral sites. The averages of MgO, SiO2 are 3.5% and 52.6% respectively. The evolved glauconite within the shelfal Mahadek Formation demarcates the stratigraphic condensation at the top of the transgressive deposits. The formation of glauconite in the late Cretaceous Mahadek Formation is significant because of its stratigraphic preference close to the K/Pg boundary.
Statistical observations of electron-scale structures in magnetosheath turbulence
Authors: Chasapis Alexandros , Ergun Bob , Ahmadi Narges , Schwartz Steven , Chhiber Rohit , Bandyopadhyay Riddhi , Matthaeus William , Retino Alessandro , LeContel Olivier , Giles Barbara , Gershman Daniel , Strangeway Robert , Russell Christopher , Torbert Roy , Moore Thomas , Burch James
Published: February 2023

Turbulence is characterized by the formation of small-scale structures, observed to occur down to electron scales. Furthermore, spacecraft observations have found active magnetic reconnection within such electron-scale current sheets. This points to small-scale structures serving as a pathway of energy conversion in collisonless plasma turbulence. However, the extent of their contribution to turbulent energy dissipation, compared to other energy conversion mechanisms, is still under investigation. The instruments of the MMS spacecraft are able to adequately resolve electron-scale processes, and in recent years have been gathering a large volume of burst resolution data in near-Earth space, allowing us to investigate this further. Here, we present the results of a statistical study of electron-scale structures observed by MMS in Earth’s magnetosheath. We show that the abundance of these structures as well as their properties, appear to depend more on the local turbulence parameters rather than on the large-scale dynamics of the magnetosheath, and bow-shock configuration. We report their contribution to the overall dissipation and their significance in plasma heating and particle acceleration. These results provide further insight into the pathways of energy conversion in collisionless turbulence, and contribute to our understanding of turbulent dissipation and particle energization. 
Supply and demand assessment and mismatch analysis of ecosystem services to support sustainable land management
Authors: Kim Jiwon , Hong Mina , Choi Sol-E , Song Cholho , Lim Chul-Hee , Choi Yun Eui , Lee Woo-Kyun
Published: February 2023

Due to the land degradation, the land use conflicts have intensified, and there is an increasing necessity to adapt sustainable land management. Sustainable land management deals with the demands for land in terms of not only human society but also the nature conservation and biodiversity. To persue and realize sustainable land management, the indicators and evaluation system are necessary, and ecosystem services has emerged as the proper indicator for sustainable land management. This study focused on the balance between the demand and supply of ecosystem services. If the balance between them was maintained or supply exceeded demand, the land can be assessed to be managed sustainably. In this study, CO2 sequestration, Heat mitigation, and water provision were assessed as ecosystem service in South Korea. The supply of each ecosystem service was evaluated by using related models which had been developed and used widely in previous studies. The demand of each ecosystem service was defined based on specific figures which had already suggested as policy goals in South Kroea in purpose of drawing social consensus. Afterwards, the ecosystem services supply and demand ratio (ESDR) were calculated to show the balance between supply and demand quantified by region. As a result, the exessive demand for CO2 sequestration service was found compared to supply. The supply of heat mitigation service was found to be sufficient for the demand nationwide. However, in specific areas such as cities, the demand was higher than the supply. In the case of water provision service, the national demand was being met by some regional suppliers. Through these results, it is possible to find out the ecosystem services that need to be supplemented spatially and regionally, and ultimately, it is expected to support the establishment of urban space, green space, and environmental planning at the regional and national levels.
Impacts of soil management on the pore structure of boreal arable clay soils
Authors: Hyväluoma Jari , Niemi Petri , Brobbey Kofi , Kinnunen Sami , Miettinen Arttu , Keskinen Riikka , Soinne Helena
Published: February 2023

Soil management is known to have significant effects on soil structure. Especially, grassland renovation and associated ploughing may have destructive influence on structure, but on the other hand conversion of arable land to grassland can improve pore structure and soil functions. In crop rotations including perennial grasses, soil structure is affected by these counteracting processes. The purpose of this work was to study and quantify the impacts of varying soil management practices on the structure of boreal arable heavy clay soils. We studied intact topsoil samples collected from two sites by X-ray computed microtomography, image analysis, image-based pore-scale flow simulations, and water retention measurements. At both sites, one area under long-term (at least 30-year-old) grassland was compared with adjacent field area with contrasting managements:Site 1: Cereal production under no-till management for 13 years prior to sampling.
Site 2: Crop rotation of a livestock farm with cereals and perennial grasses, tillage by ploughing. At the sampling time this field area had been two years under grass after preceding 3-year cereal period.
Both imaging and water retention showed statistically and practically significant differences in the soil macropore structure at site 1 such that porosity of the long-term grassland was clearly higher that that under cereal production. On the contrary, at site 2, only minor differences between managements were observed. Our results show that the soil management practices affect the macropore structure of boreal arable clay soil and that no-till and crop-rotation managements had clearly different effects on soil structure as compared to long-term grasslands.
Modelling the thermodynamic growth of sea ice: insights from quasi-static models
Authors: Rees Jones David
Published: February 2023

The thermodynamic growth of sea ice is governed by heat transfer through the ice together with appropriate boundary conditions at the interfaces with the atmosphere and ocean. Several different representations of this process have been used in climate modelling, including the simplest zero-layer models (Semtner, 1976) and more complex partial-differential-equation-based models (Maykut & Untersteiner, 1971; Bitz & Lipscomb, 1999). Recently, these latter models have been extended to include a representation of the dynamic evolution of the salinity of sea ice based on mushy-layer theory (Turner et al., 2013; Griewank & Notz, 2013; Rees Jones and Worster, 2014). Salinity variation might be expected to have a significant effect on ice growth given that it controls the relative proportions of solid ice and liquid brine, and these materials have different thermal properties. In this study, we develop a simplified framework to investigate the effects of variations in the thermal properties of sea ice. We develop and test a quasi-static simplification. In this simplification, we apply a transformation to the underlying heat equation such that the spatial coordinate scales with the ice thickness. We then neglect the explicit time dependence. This procedure reduces the full partial differential equation to an ordinary differential equation. The solution is exact for constant forcing conditions. We show that ice salinity has only a modest effect on the growth rate, notwithstanding its large effect on the thermal properties of sea ice. The model allows us to unpick the physical causes, which are related to the trade-off between the effect of salinity on thermal conductivity and latent heat release. We calculate the growth of ice under steady and time-dependent forcing. Under steady forcing, the ice growth equation admits an analytical approximate solution, which compares well to numerical solutions. We show that saltier ice initially grows slightly faster but subsequently grows slightly slower, a further trade-off explaining the relatively weak sensitivity of ice growth to salinity.Under time-dependent forcing, we show that the quasi-static model compares well to full partial-differential-equation-based models. So our approach offers intermediate complexity between zero-layer Semtner models and full models based on partial differential equations such as Maykut-Untersteiner/Bitz-Lipscomb/mushy-layer models.References:Semtner, A. J. (1976) J. Phys. Oceanogr. 6 (3), 379–389.Maykut, G. A. & Untersteiner, N. (1971) J. Geophys. Res. 76 (6), 1550–1575.Bitz, C. M. & Lipscomb, W. H. (1999) J. Geophys. Res. – Oceans 104 (C7), 15669–15677.Turner, A. K., Hunke, E. C. & Bitz, C. M. (2013) J. Geophys. Res. – Oceans 118 (5), 2279–2294.Griewank, P. J. & Notz, D. (2013) J. Geophys. Res. – Oceans 118 (7), 3370–3386.Rees Jones, D. W. & Worster, M. G. (2014) J. Geophys. Res. – Oceans 119 (9), 5599–5621.